Chapter 29

Pediatric Surgery

Eric Strauch

Charles W. Wagner

I Introduction

Pediatric surgery has evolved as a subspecialty for several reasons. First, infants and children differ from adults physiologically as well as anatomically. For example, the nutritional needs and fluid and electrolyte management for infants and children are not the same as those required for adults. Therefore, specialized knowledge is required for the care of pediatric surgical patients. Second, infants and children also differ to some extent with regard to the types of disorders that require surgical management. In infants, congenital malformations require prompt correction, and specialized knowledge is needed. The full discussion of specialized pediatric considerations is much too extensive to be covered in this chapter; therefore, only certain topics are discussed. For more complete information, the reader can consult standard textbooks on pediatric surgery.

II Congenital Hernias (see Chapter 2, III)

A Inguinal hernia

Repair of an inguinal hernia remains the most common general surgical procedure in the case of the child. The defect is caused by nonfusion of the processus vaginalis and not by a breakdown of the floor of the inguinal canal.

Incidence

Inguinal hernia occurs in 1%–3% of all children.

The hernia is on the right approximately 60% of the time, on the left approximately 30% of the time, and bilateral between 10% and 15% of the time.

The male:female ratio is 6:1.

In premature infants, the incidence is 1½ to 2 times greater.

The incidence of hernias is increased in patients with hydrocephalus who are treated with ventriculoperitoneal (VP) shunts, in patients with connective tissue disorders, and in infants and children on peritoneal dialysis.

Clinical presentation

An inguinal hernia is diagnosed in infancy, and approximately 35% of patients present before 6 months of age.

The classic history and clinical presentation are those of a mass or bulge in the groin, scrotum, or labia, which usually occurs during times of abdominal pain. The mass usually disappears after the straining or crying has been resolved, but it is for the most part easily reducible.

If no mass is present, the physician can feel the thickened spermatic cord, which represents the nondistended hernia sac. This cord has been described as the “silk glove” sign.

If no hernia is identified but the patient's history is both classic and reliable, most surgeons believe that surgery is indicated.

Incarceration

In boys , the risk associated with a hernia is the chance of incarceration of the intestine.

Intestinal ischemia and obstruction can occur.

With time, the entrapped bowel becomes edematous enough to compress the spermatic vessels and cause testicular ischemia with resultant damage or necrosis.

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The risk of incarceration in a premature infant is 2–5 times higher than in the older child.

In girls , incarceration of the ovary is more common than incarceration of the intestine. Although ischemia of the ovary may result, it does not usually occur.

Treatment includes reduction of the incarcerated hernia, hydration of the patient, and herniorrhaphy.

These steps should all be taken within 48–72 hours.

Reduction is performed with or without sedation by gentle, continuous pressure on the incarcerated intestine.

Most hernias in children will reduce, but if the hernia cannot be reduced, emergent repair, evaluation of the intestine, and resection of necrotic intestine needs to be performed. The chance of reducing necrotic intestine is very low.

Herniorrhaphy. A hernia should be repaired soon after it is diagnosed, unless a major medical reason prohibits the use of anesthesia. In most children, the hernia can be repaired with outpatient surgery. Premature infants may have apnea and bradycardia after surgery and require overnight admission for monitoring for these conditions. Small infants with lung disease can have their hernias repaired under spinal anesthesia.

Procedure. Herniorrhaphy in the child consists of identifying the sac, dissecting the spermatic structures free, and ligating the sac high at the internal ring of the inguinal canal. Floor repair is rarely needed.

Complications of the procedure include damage to the vas deferens, vascular injury to the testes, recurrence of the hernia, and iatrogenic cryptorchidism.

The recurrence rate is reported to be approximately 1%, and the highest frequency occurs in patients with incarcerated hernias, connective tissue disorders (e.g., Ehler -Danlos or Hunter's syndrome), or increased intra -abdominal pressure (VP shunts or peritoneal dialysis [PD] catheters).

Iatrogenic cryptorchidism occurs when the testicle has been mobilized from the scrotum but has not been properly replaced. Unlike regular cryptorchidism, in which the testes may later descend, the testes remain in the abnormally high position with iatrogenic cryptorchidism.

B

Diaphragmatic hernias are communications through the diaphragm that allow abdominal contents to migrate into the thoracic cavity.

Incidence. The incidence of this defect is 1 in 4,000 live births.

Etiology. Two underlying anatomic defects are common; both result from the failure of the surrounding tissues to fuse in utero.

The foramen of Bochdalek is a posterolateral diaphragmatic defect.

This hernia is the most common congenital hernia (Fig. 29 -1).

It occurs most often in the left hemidiaphragm and is bilateral in fewer than 10% of infants.

The foramen of Morgagni is an anterior diaphragmatic defect. It is much less common and generally results in less severe problems.

Diagnosis of herniation of abdominal contents into the thorax is based primarily on impaired ventilatory capacity. The earlier that respiratory distress is noted in the infant (especially if it occurs during the first 24 hours), the more severe will be the impairment and the worse the prognosis.

The physical examination reveals the following:

Tachypnea, dyspnea, use of accessory muscles for ventilation, cyanosis, and nasal flaring are evident.

Breath sounds are decreased or absent on the affected side.

Heart sounds are shifted away from the affected side.

Bowel sounds are heard in the affected hemithorax.

A scaphoid abdomen is caused by the migration of abdominal contents into the chest.

A chest radiograph shows signs typical of herniation.

A loculated gas pattern is found in the affected hemithorax.

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FIGURE 29-1 Bochdalek's hernia.

A mediastinal shift occurs away from the hernia.

Atelectasis occurs in the unaffected lung.

The nasogastric tube is found in the affected hemithorax after passage of the tube through the nose or mouth.

Preoperative management

Gastrointestinal decompression should be performed via a nasogastric or orogastric tube.

A pneumothorax in the unaffected hemithorax should be sought and, if present, treated with a chest tube.

Preoperative management is aimed at both respiratory insufficiency and pulmonary vascular hypertension.

Hypoxemia due to hypoplastic lung(s) causes acidosis.

Acidosis causes pulmonary vasculature to constrict, which decreases blood flow to the lung and increases the right -to -left shunt.

If hypoxemia and hypercarbia can be improved with routine ventilator methods, surgical repair should then proceed.

If acidosis with hypoxemia persists, preoperative use of extracorporeal membrane oxygenation (ECMO) should be considered.

The hernia can be repaired while using ECMO.

The use of nitric oxide (NO) is increasing as a step to improve hypoxemia. This agent is a potent pulmonary vasodilator and is mixed with the gases used in the ventilator. By dilating the pulmonary vasculature, the right -to -left shunt decreases.

Operative management is based on the following principles:

The herniated contents are reduced surgically back into the abdomen (through an abdominal incision), which can immediately relieve the distress.

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The hernia defect is repaired.

An exploratory laparotomy is carried out to diagnose associated congenital anomalies (intestinal malrotation is often associated with this hernia).

A chest tube can be inserted into the affected hemithorax but should not be placed on suction.

The infant's acid -base balance and respiratory function are monitored carefully.

A nasogastric tube is left to decompress the gastrointestinal tract.

Postoperative management is aimed primarily at maintaining adequate ventilation and perfusion and includes the following:

Respiratory support on a ventilator is given as needed, and arterial blood gases are monitored.

Atelectasis of either lung is treated, and the retained secretions are prevented.

Chest tube suction is used on the affected side to stabilize the mediastinum in the midline.

The patient is observed for contralateral pneumothorax and is treated rapidly if it occurs.

Adequate gastrointestinal compression is provided.

The abdomen is small and may not be able to hold all of the contents after reduction.

The loss of the “right of domain” of the abdominal contents greatly distends the abdomen and raises intra -abdominal pressures.

Abdominal distention significantly impairs both thoracic excursion and venous return from the lower body.

ECMO can also be initiated during postoperative care.

The oxygenator allows correction of hypoxemia and acidosis, thus decreasing the pulmonary vascular hypertension.

The patient is slowly weaned from ECMO so that normal pulmonary physiology can occur.

If NO is used, levels of methemoglobulin are monitored. If greater than 5, one must decrease the concentration of NO in the ventilator gas mix.

The use of diuretics to aid in fluid management is now being recognized as an important part of care in congenital diaphragmatic hernias.

The prognosis for the infant with a diaphragmatic hernia is a function of the preoperative severity and time of presentation of this hernia.

The immediate mortality rate is approximately 35%–40%.

The resolution of respiratory insufficiency in the postoperative period depends on the maturity of the contralateral lung and the control of pulmonary hypertension.

The ipsilateral lung is almost always hypoplastic when a diaphragmatic hernia is present and, therefore, does not aid in respiratory function during the immediate postoperative period.

If the infant survives, the lung eventually develops.

No permanent respiratory difficulties have been noted in later life once the acute pulmonary insufficiency has resolved.

Patients who have been treated with ECMO have a survival rate of 65%. Associated risks (e.g., bleeding, cerebral infarction, recurrent hernias) keep this modality from being used routinely.

Other therapeutic interventions being investigated are high-frequency ventilation (which prevents barotrauma to the already hypoplastic lung). NO acts as a potent pulmonary vasodilator.

III Abdominal Wall Defects

A Types

The two types of abdominal wall defects are gastroschisis and omphalocele. Although the abdominal contents are located outside of the peritoneal cavity in each type, the similarities (both developmental and therapeutic) end at that point.

Gastroschisis is an opening in the abdominal wall, immediately adjacent to the right of the umbilicus, which is located in the normal position.

During fetal development, the abdominal wall is completely formed, but the peritoneal cavity does not enlarge enough to hold the abdominal contents.

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The protruding viscera, which consist of the midportion of the small intestine, the spleen, the stomach, the colon, and occasionally the liver, has no protective covering.

The intestine is edematous, semirigid, leathery, and matted together as a result of chemical peritonitis.

Associated anomalies and syndromes are rare, and intestinal atresia is the most frequent (10% of cases) anomaly.

Omphalocele is an opening in the abdominal wall at the umbilicus.

It is caused by incomplete closure of the somatic folds of the anterior abdominal wall in the fetus.

Unless ruptured, a sac covers the extruded visceral contents, and no signs of chemical peritonitis appear.

The liver and small bowel are the organs that most commonly protrude through the defect.

The omphalocele may be a part of the pentalogy of Cantrell, which also includes:

Diaphragmatic hernia

Cleft sternum

Absent pericardium

Intracardiac defects

If the caudal folds are involved, exstrophy of the bladder or cloacal exstrophy is present.

Associated anomalies. Approximately 50% of these infants have one or more associated anomalies, including trisomies 13 and 18; Beckwith's syndrome; and cardiac, neurologic, and genitourinary malformations.

B

Prenatal diagnosis may be made by the use of ultrasonography. This visualization of deep structures aids in the diagnosis of associated anomalies and in prenatal counseling as well as in early post delivery management.

C

Preoperative management is similar in both disorders.

Gastrointestinal decompression, intravenous fluids, and antibiotics are instituted.

Protection of the abdominal contents is imperative, especially because the escape of moisture and heat is considerable in these patients.

The unruptured omphalocele is left intact and protected with a sterile dressing to prevent it from drying out.

Gastroschisis or a ruptured omphalocele is protected under a plastic covering (intestinal bag).

When the patient with gastroschisis has a small defect and a swollen intestine, kinking of the vascular supply may occur at the edge of the defect. This vascular compromise may be prevented by placing the infant on his or her side. Occasionally, emergent enlargement of the defect may be necessary to protect the blood supply to the intestine.

The outcome of gastroschisis is related to the condition of the intestines at the time of surgery.

D

Operative management differs slightly for the two disorders. However, the goal in both conditions is to cover the abdominal viscera either with prosthetic material or with the abdominal wall itself.

Gastroschisis. Closure is emergent, as there is no covering over the gastrointestinal tract to prevent heat and fluid losses. Primary closure involves decompressing the gastrointestinal tract and stretching the abdominal wall over the defect.

If the closure is too tight, the blood supply to the intestine, abdominal wall, or lower extremities is compromised. To avoid this complication, it is better to cover the exposed organs temporarily with prosthetic materials.

Preconstructed silicon ventral wall defect silo bags are now available for staged closure. They eliminate suture lines that leak, and they also have a spring anchoring device for ease of application.

Reduction can now usually be completed by days 5–7, thus minimizing the risk of infection.

A nasogastric tube is placed for decompression with either method of treatment.

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Omphalocele. A ruptured omphalocele, like a gastroschisis must be covered emergently. If the sac is intact, workup for associated defects such as a cardiac anomaly can be performed. The choice of procedures includes primary closure; staged repair; or, for an unruptured omphalocele, nonoperative management. The important factor is the size of the defect.

The greater the size of the defect, the less the peritoneal cavity has enlarged with adequate musculature of the abdominal wall; with a large defect, primary closure may involve too much tension.

An alternative method of treatment is to cover the defect with skin flaps, leaving the resultant

ventral hernia to be repaired later on.

Silastic sheeting or preconstructed silo bags can be used to stage the repair; by keeping tension on the prosthetic sac, the Silastic sheet stretches the abdominal wall enough to accommodate the herniated viscera.

As with a staged repair of gastroschisis, closure is usually accomplished within 10 days.

A prosthetic material such as Alloderm can be used to close the defect.

Nonoperative management is an alternative in patients with associated anomalies.

The sac is coated with silver sulfadiazine (Silvadene).

An eschar forms with subsequent coverage by granulation tissue.

The resultant ventral hernia can be repaired later on.

The risks associated with this method are rupture of the sac, requiring subsequent repair in an infected area; sepsis; undiagnosed intestinal atresia; and prolonged hospitalization.

As with gastroschisis, a nasogastric tube is placed for decompression.

E Postoperative management

With primary closure, respiration may be inhibited if the reduced abdominal contents compress the diaphragm. Patients may require muscular paralysis and mechanical ventilation until the abdomen stretches enough to accommodate the viscera.

Venous return may be compromised owing to compression of the inferior vena cava.

For vascular access, upper extremity veins should be used.

The legs may show signs of venous obstruction and resultant edema.

With staged repair, the patient needs to be observed after each daily reduction for both respiratory compromise and decreased venous return due to increased abdominal pressure.

Patients require hyperalimentation with both primary and staged repairs, because intestinal motility and absorption are slow to return.

After an unruptured omphalocele has been repaired, intestinal function is not as delayed as gastroschisis; however, hyperalimentation may still be needed.

F Prognosis

Gastroschisis , although more difficult to manage initially, has very few long-term problems.

Intestinal strictures may occur at the site of evisceration and will require resection later on.

The mortality rate , approximately 30% in the past, has improved greatly with the use of hyperalimentation and is now approximately 5%. Mortality is related to sepsis and the viability of the gastrointestinal tract at the time of surgery.

With resection for intestinal gangrene, short-bowel syndrome may develop.

Omphalocele. The outcome for an omphalocele is related to the size and location of the defect and to the presence of associated anomalies. The overall mortality rate ranges from 20%–60%.

IV Esophageal Atresia and Tracheoesophageal Malformations

Esophageal atresia and tracheoesophageal malformations occur once in every 3,000 live births. They encompass a spectrum of lesions that can vary greatly in their time of presentation and in their treatment. A high incidence of associated maldevelopments in other organ systems may complicate the treatment of these patients.

A Types of lesions

(Fig. 29 -2)

Esophageal atresia (proximal pouch) with a distal tracheoesophageal fistula is the most common type; it occurs in 86% of patients.

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FIGURE 29-2 Esophageal atresia. A: Esophageal atresia with distal tracheoesophageal fistula. B: Proximal and distal blind pouches without fistula. C: H fistula. D: Esophageal atresia with proximal tracheoesophageal fistula. (Adapted from

Altman RP, et al. Pediatric surgery. In Guzetta PC, Anderson KD, Altman RP et al. eds. Principles of Surgery, 7th ed. New York: McGraw-Hill; 1989:1724.

)

Pure esophageal atresia (proximal and distal blind pouches) without a fistula occurs in 7% of patients.

Tracheoesophageal fistula without atresia (the H fistula) occurs in 5% of patients.

A proximal and a distal tracheoesophageal fistula are combined with a proximal atresia (the least common type) in 2% of patients.

B Associated anomalies

In approximately 40% of these patients, other malformations are present in one or more organ systems.

An endocardial cushion defect affects the heart, which is the most common single involved organ.

The VACTERL complex, a well-recognized anomaly complex, involves vertebral, anal defects, cardiac anomalies, tracheoesophageal fistula, renal and l imb dysplasia.

The complex may be fully or partially demonstrated; that is, one or any combination of lesions may occur.

If it seems to be partial, the complete complex must be ruled out.

C

The diagnosis of esophageal atresia and tracheoesophageal fistula is usually made soon after birth, when the affected infant exhibits some form of respiratory distress.

Physical examination

Aspiration of material from the upper pouch causes some symptoms.

The infant may appear to be salivating excessively and may drool continuously.

The aspiration may also cause coughing spasms, intermittent choking, or cyanosis that develops when the infant is feeding.

Continuous aspiration of gastric secretions occurs if a fistula is present. This aspiration is more severe and more harmful than that from the upper pouch.

Tachypnea and signs of pneumonia may develop.

A scaphoid abdomen due to the unused gastrointestinal tract accompanies pure atresia.

Attempts to pass a tube through the nose into the stomach will fail, because the tube will stop in the blind pouch of the esophagus, thus confirming the suspicion of esophageal atresia.

Radiographs of both the chest and the abdomen are important in order to make a diagnosis and to prepare for treatment.

The chest film will show the blind upper pouch and also the failure of passage by the gastric tube.

A gasfree abdomen is characteristic of pure atresia.

Hyperventilation, atelectasis, or pneumonia must be evaluated so that the proper surgical approach (i.e., immediate vs. delayed repair) can be chosen.

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Identification of the aortic arch is also necessary for proper surgical management. The use of echocardiography may also assist in determining not only the aortic anatomy but also any associated congenital heart anomalies (see IV B ).

The length of the esophageal defect can be measured on a lateral film.

D Preoperative management

Several steps should be taken once the diagnosis is made.

Decompression of the proximal pouch by means of a sump tube with constant suction (Replogle tube) is required.

An upright position is maintained, using a chalasia chair.

Gastrostomy is performed if delayed repair is chosen.

This procedure prevents further gastric aspiration.

It also provides a route for preoperative feedings if surgery is delayed for an extended period.

Stretching the proximal pouch daily in a pure atresia shortens the distance between the esophageal ends in preparation for eventual repair.

E Operative management

Primary repair at the time of presentation can be undertaken if the defect measures less than 2 cm and no signs of pneumonitis are present. Delayed repair may be needed if the defect is greater than 2 cm or extends the length of 2½ vertebral bodies. At the time of surgery, the approach is the same for either immediate or delayed repair.

Broad -spectrum antibiotic therapy is begun.

If not previously undertaken, a gastrostomy may be performed, although this measure is controversial.

An extrapleural dissection through the hemithorax opposite the aortic arch is currently favored to prevent empyema from occurring as the result of an anastomotic leak.

The tracheoesophageal fistula is repaired.

A primary esophagostomy is performed.

The distal esophagus must be carefully dissected because the blood supply is tenuous.

An adequate length of esophagus is necessary to create a tensionfree anastomosis and is obtained by dissecting the proximal pouch. The use of myotomies may aid in gaining length for closure.

A drain is placed in the extrapleural space.

F

Postoperative management is directed at potential pulmonary and esophageal problems.

The infant is extubated as soon as possible to protect the tracheal repair.

Vigorous pulmonary toilet is necessary to clear up any previous pneumonia and to prevent the need for reintubation.

Reintubation may disrupt the esophageal repair, the tracheal repair, or both.

A degree of tracheal malacia compromises pulmonary function.

Chest percussion is mandatory to prevent early postoperative problems.

The infant is kept upright, because esophageal function will not yet be adequate for swallowing oral secretions.

Esophagotracheal suction is done carefully and with a specifically defined length of tubing. Disruptions of the esophagus can occur during placement of a suction catheter through the anastomotic line.

The esophagus is evaluated after 7 days by means of a swallow study.

If no leak is present, oral feedings are started; if feedings are tolerated, the extrapleural drain is removed.

Normal in utero development. The midgut develops extra-abdominally. It then migrates intraperitoneally, where it undergoes a 270 -degree rotation. The results are as follows:

The cecum ends up in the right lower quadrant.

FIGURE 29-3 Malrotation and volvulus of the midgut.

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The right colon becomes fixed in the right paracolic gutter.

The duodenum becomes fixed in the retroperitoneal location, with the superior mesenteric artery passing over the duodenum.

Displacements caused by malrotation

The cecum is not in the right lower quadrant, and the duodenum does not pass posteriorly to the superior mesenteric artery.

Instead of the base of the small bowel being fixed from the ligament of Treitz to the cecum in the right lower quadrant, the whole midgut is anchored on the superior mesenteric artery.

Various stages of fixation of the cecum can be seen, but it is usually fixed to the right upper quadrant with the fibrinous bands (Ladd's bands) that extend across the second portion of the duodenum.

Sequelae to malrotation. Two serious problems may accompany this lesion, which must, therefore, be handled expeditiously.

Intestinal obstruction can result from adhesive bands across the second portion of the duodenum

fixing to the right upper quadrant.

A midgut volvulus, which is more serious than intestinal obstruction, can also occur.

This volvulus develops when the intestine twists on its vascular pedicle (the superior mesenteric artery) and causes ischemia as well as obstruction of the entire midgut.

The result can be catastrophic, and gangrene of the entire small bowel can occur.

Symptomatic malrotation is now being recognized in the older child. This is manifested by an atypical type of abdominal pain or vomiting caused by a partial or intermittent duodenal obstruction. Volvulus is rare in this group, but cases have been reported.

B Clinical presentation

Bilious vomiting is the usual presenting symptom.

Passage of a bloody stool is a late occurrence and implies ischemia, with necrosis of the bowel mucosa, bowel wall, or both.

The infant may appear normal, with hemodynamic stability, or may be dehydrated and in shock.

C

Early diagnosis of malrotation is crucial to prevent the development of a volvulus with resultant intestinal gangrene. Therefore, when malrotation in an infant is suspected and cannot be ruled out, all efforts are made to confirm the diagnosis rapidly.

Radiographs are very useful when making the diagnosis.

The plain film may demonstrate the “double -bubble” sign, which is produced by intestinal gas confined to the stomach and duodenum, with small amounts of gas in the residual, unused gastrointestinal tract. In a newborn with bilious vomiting, this sign is an indication for surgery.

The upper gastrointestinal series may demonstrate an abnormally located ligament of Treitz, the presence of the duodenum to the left of midline, a duodenal obstruction, or a “beaked” end in the barium column at the point of the intestinal twist.

Prompt surgical exploration is imperative if the diagnosis of malrotation is suspected but cannot be ruled out, because most infants with obstructive malrotation have a volvulus.

D Operative management

Surgical procedures for malrotation vary with the presence or absence of volvulus and the status of the intestine.

Simple malrotation is treated by the Ladd procedure.

This procedure consists of releasing the adhesive bands and mobilizing the duodenum. The goal is to broaden the mesentery of the intestine as much as possible and to separate the duodenum and ascending colon.

The cecum is placed in the left upper quadrant and the duodenum in the right lateral abdomen so that both organs will be in positions that should prevent intestinal obstruction or ischemia.

An appendectomy is performed, and the remaining abdominal contents are examined for other anomalies, such as a duodenal web.

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Malrotation with volvulus requires several preliminary steps.

The first step is a counterclockwise detorsion of the midgut volvulus.

The bowel is then examined for viability and for areas of necrosis.

If small areas of gangrene are present, resection is performed, followed by the Ladd procedure.

If large amounts of the midgut appear necrotic, long lengths of bowel are not resected. Instead, the bowel is untwisted, and the abdomen is closed and then re-explored 24 hours later. This second look allows marginally viable tissue to recover, with the hope of minimizing the amount of bowel to be resected.

E Prognosis

The recurrence of a midgut volvulus after surgical exploration and a Ladd procedure occurs in as many as 10% of cases, usually in the immediate postoperative period.

The long-term sequelae are minimal after repair of simple malrotation. However, when extensive intestinal resection is required, the result depends strongly on the amount of intestine remaining. Extreme resections result in severe malabsorption and even in death.

VI Intestinal Atresia

A

Duodenal atresia and stenosis occur because the second portion of the duodenum fails to recanalize in the early embryonic stages. The lesion may be complex, partial, or in the form of a web (which is identified by an upper gastrointestinal study).

Associated anomalies

Trisomy 21 occurs in 30% of infants with duodenal malformations.

Cardiac lesions and various elements of the VACTERL complex are present in many infants.

An annular pancreas may be present, with the pancreas forming a ring around the duodenum. This anomaly is now thought to result from the malformation, rather than being a cause of duodenal stenosis.

The diagnosis is usually made from two simple findings.

Bilious vomiting that occurs soon after birth in a nondistended infant suggests a high obstruction.

Abdominal radiographs show the classic double -bubble sign, which involves air in the stomach and a proximally dilated duodenum.

This sign suggests duodenal obstruction but can also be seen with malrotation.

Although duodenal atresia or stenosis in itself is not life threatening, malrotation is life threatening (see V ).

If delay in treatment is being considered in the patient with a double -bubble radiograph, a barium contrast study is necessary to rule out malrotation.

This study may be a barium enema to localize the cecum or an upper gastrointestinal study to see the duodenal sweep.

Preoperative management

Gastric decompression and fluid resuscitation are performed as needed.

Broad -spectrum antibiotic therapy is begun.

Because these lesions have a high association with other more critical anomalies, stabilization and evaluation of these lesions can be done before surgery. However, this combination can be done only if malrotation is ruled out as the cause of duodenal obstruction.

Operative management has as its goal the re-establishment of a patent gastrointestinal tract.

The site of obstruction is identified.

Usually a duodenoduodenostomy can be performed. If this cannot be done, a duodenojejunostomy is a good alternative. Gastrojejunostomy is contraindicated.

If a web is present, the duodenum is opened at the site of obstruction, the web is excised, and the duodenum is closed. Care must be taken to identify the ampulla of Vater, because it is also located on the mesenteric side of the web.

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If an annular pancreas is present, care is taken not to damage this structure.

In no circumstance is the pancreas divided.

The annular pancreas is not the obstructing lesion (as is the duodenal stenosis), and the mortality rate is extremely high among patients whose annular pancreas is divided.

The annular pancreas can usually be bypassed by a duodenoduodenostomy.

Because 15% of the patients have other gastrointestinal atresias, a thorough search is undertaken to ensure the patency of the entire gastrointestinal tract.

A nasogastric tube is used for gastrointestinal decompression.

Postoperative management is simple but requires patience.

Gastrointestinal decompression is important to protect the suture line and to prevent possible aspiration.

The return of gastrointestinal function is slow, not only because of gastric and duodenal dysfunction but also because the distal intestine is small owing to disuse.

Nutritional support by hyperalimentation is usually needed.

Prognosis. Long-term results of surgery are good. Mortality in these patients is related to prematurity of the infant and to associated anomalies.

B

Jejunal, ileal, and colonic atresias are caused by in utero vascular accidents that result in ischemia of a segment of bowel, with consequent stenosis or atresia. The ileum is most commonly affected; the jejunum and colon are affected less often. The severity of the lesion is related to the size of the vascular arcade that was affected in utero.

Associated anomalies. Because they are not embryonic maldevelopments, associated anomalies are much less common than with duodenal atresia. However, approximately 10% of patients have cystic fibrosis. DNA studies to identify the cystic fibrosis gene are now available and can be used if a sweat test is inadequate or unavailable. Patients with these atresias should have a sweat chloride test by 2 months of age to rule out cystic fibrosis.

Clinical presentation. The diagnosis is suspected when an infant develops bilious vomiting after 24 hours of life.

The degree of abdominal distention varies with the level of the obstruction.

The passage of meconium does not rule out an atresia, because the gastrointestinal tract was intact before the vascular accident.

All patients with small bowel or colonic atresia should have an early evaluation for cystic fibrosis.

Diagnosis

Abdominal radiographs show various degrees of obstruction, depending on the level of the atresia or stenosis.

The picture can be confused with meconium ileus.

In atresia, air–fluid levels are present; whereas a meconium ileus shows only distended bowel, without fluid levels, and a soap -bubble appearance.

Contrast studies are helpful in both diagnosis and management.

A contrast enema will reveal colonic lesions and perhaps low ileal lesions.

Hirschsprung's disease, meconium ileus, and other congenital disorders may also be ruled out, making diagnosis of the atresia more certain.

Preoperative management includes gastrointestinal decompression and fluid replacement. Begin broadspectrum antibiotic therapy.

Operative management. Surgery is performed to re-establish intestinal continuity.

The current procedure of choice is an end -to -end intestinal anastomosis.

This procedure may be difficult to accomplish because of the marked size disparity of the bowel—the proximal bowel is dilated, and the distal, unused bowel is small.

Because of the variations in size, tapering of the proximal bowel may aid in the repair.

The distended bowel has been found to have varying degrees of impaired motility. Therefore, gastrointestinal function may be extremely slow to return.

A nasogastric tube is placed to allow decompression, prevent aspiration, and protect the suture line.

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A thorough abdominal examination for multiple atresias is performed. Their overall occurrence rate is 6%, but the frequency is high with ileal atresia and very low with colonic atresia.

In a patient with both an atresia and meconium ileus , the distal intestine may contain inspissated small bowel secretions. In this situation, the site of inspissation should be irrigated with a 4% acetylcysteine (Mucomyst) solution to relieve any potential obstruction before the atresia is repaired.

Postoperative management involves decompression and patience.

Hyperalimentation may be needed until the gastrointestinal tract begins to function.

Malabsorption, if present, may prolong the recovery time.

Prognosis. Because associated anomalies are few, survival is a function of the prematurity of the infant. Current results show a survival rate of almost 100%.

C

“Apple -peel” atresia, a severe form of small bowel atresia, is known by this name because of its appearance.

This atresia occurs during a large vascular accident to one or more of the mesenteric arcades in utero.

Stenting procedures have been developed to preserve gastrointestinal length in patients with both apple - peel and multiple atresias.

In these patients, return of gastrointestinal function is very prolonged, and malabsorption is common.

VII Imperforate Anus (Fig. 29-4)

Abnormal termination of the anorectum has a clinical spectrum that ranges from a fistulous opening in the perineal area or a colourethral fistula to a completely blind ending of the rectum. The incidence of these malformations ranges from 1 in 1,500 to 1 in 5,000 births. The male:female ratio is 2:1.

A Types

Although many classifications have been proposed for an imperforate anus, the simplest division is on the basis of sex and the relationship to the levator ani.

Infralevator (low) type. The rectum passes through the puborectalis sling. This type is more common in girls.

Supralevator (high) type. The rectum does not pass through the puborectalis sling. This type is more common in boys.

B

Associated anomalies are common in patients with an imperforate anus, and this congenital defect is associated with the VACTERL syndrome.

The genitourinary tract is the most commonly involved organ system.

Malformations include renal agenesis, renal dysplasia, hypospadias, epispadias, bladder exstrophy, vaginal atresia, and cloacal exstrophy.

These findings have been reported in up to 40% of patients with imperforate anus.

The patient may have a fistulous tract, which opens:

In girls, posterior to the vagina within the vestibule

In boys, to the posterior urethra

In boys, meconium in the urine should be sought. This condition occurs only when a fistula is present between the rectal pouch and the urinary tract.

Problems in patients with fistulas

They may develop symptomatic urinary tract infections.

They may also develop a hyperchloremic acidosis caused by reabsorption of chloride by the colonic mucosa.

This acidosis is characterized by lethargy, tachypnea, and elevation of the serum chloride and the blood urea nitrogen (BUN).

Although the condition may resolve in time, treatment with bicarbonate may be required; and, if the condition is severe or cannot be corrected, the rectal pouch–urinary tract fistula may need to be divided before the definitive procedure is undertaken.

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Radiographs. If no external fistula is identified, the surgeon must determine whether the rectum has traversed the puborectalis sling. Using a cross-table lateral radiograph of the pelvis, the surgeon can identify the extent of the rectum by visualizing the end of the infracolonic air.

A line drawn from the posterior portion of the symphysis pubis to the tip of the coccyx (the pubococcygeal line) aids when differentiating the infralevator type from the supralevator type.

Air visible in the bladder suggests a posterior urethral fistula, which implies a supralevator type.

If the distance from the tip of the colonic air column to the anal dimple is greater than 2 cm, the lesion is the supralevator type. An ultrasound examination may prove more accurate in defining the distance.

D Operative management

Infralevator type. If an external fistula is identified, several alternatives are available for the initial management.

If the fistula can be dilated, it may function satisfactorily until the patient is older, at which time the opening can be relocated to the correct site (the Pott's anal transfer).

If the mucosa is close to the opening, the fistula may be enlarged by a procedure known as a Denis

Browne cutback.

These procedures are performed more commonly in girls, because the infralevator type of imperforate anus occurs more often in girls.

Supralevator type. The treatment for the supralevator type of imperforate anus is, first, the formation of a colostomy, followed by the formation of a neorectum and anus.

The sagittal posterior anoplasty (Peña procedure) has been used for reconstruction of all levels of imperforate anus. The goal is to bring the rectum down to the perineum within the sphincter complex to try and maximize continence.

E

Postoperative management depends on the type of imperforate anus. Basically, the goal of treatment in these patients is to have a socially accepted, continent child. These children require patience during toilet training; they are usually trained between 3 and 5 years of age.

Infralevator types of anus require constant dilatations until the stool obtains bulk.

Supralevator types of anus require colostomy care until the definitive procedure can be performed. With the formation of a new anus, the patient may require dilatations to prevent strictures.

F Prognosis

The mortality rate among patients with an imperforate anus is directly related to the associated anomalies.

Functional morbidity is directly related to:

Inappropriate management

Associated neurologic dysfunction due either to spina bifida or to sacral agenesis with poorly developed neuromuscular control in the lower pelvis

The development and use of either irrigating stomas or cecostomy buttons for prograde enemas have shown a simple solution for a poor outcome (constipation or soilage).

VIII Hirschsprung's Disease

A Overview

Hirschsprung's disease is caused by the congenital absence of parasympathetic ganglia cells in the wall of the gastrointestinal tract.

As a result, the affected portions of the bowel are unable to relax and allow effective peristalsis to occur.

Hirschsprung's disease always involves the rectum and extends proximally with no skip areas. Any other part of the gastrointestinal tract, or even the entire tract, may also be involved.

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Male predominance is 4:1, except when the entire colon is involved. In that situation, the frequency ratio is reversed, with females predominating.

Approximately 30% of patients with Hirschsprung's disease have a relative afflicted with the disease.

B Clinical presentation

Hirschsprung's disease may go undiagnosed for years after birth. It should be suspected in any patient with a chronic unexplained illness and an abnormal bowel pattern dating back to early infancy.

Newborns with Hirschsprung's disease present with a history of nonpassage of meconium.

Meconium is usually passed within 24 hours after birth in term infants and within 48 hours in

premature infants.

Distention and bilious vomiting are common.

Physical examination in the newborn reveals a distended abdomen.

Occasionally, loops of stool -filled bowel may be palpated.

A rectal examination shows the ampulla or rectal vault to be empty and the sphincter tone to be increased. Classically, when the examining finger is removed, an explosion of watery stool occurs.

Infants and older children have a history of obstipation and constipation as well as failure to thrive.

Bouts of diarrhea, vomiting, and abdominal distention may herald the development of enterocolitis.

Enterocolitis is sometimes associated with Hirschsprung's disease. If left untreated, it has a high mortality rate (up to 50%).

C

The diagnosis is confirmed by radiographic and tissue studies.

Abdominal radiographs reveal air–fluid levels and a distended bowel. Often, no air is seen in the rectum.

Barium enema shows spasm and a narrowed lumen in the affected bowel.

A transition zone is often present, showing a dilated proximal gut and a narrowed distal gut.

This zone represents the most distal area in which ganglia cells are present.

In most patients, this zone is in the rectosigmoid segment of the colon.

The ratio of the diameter of the sigmoid colon to the diameter of the rectum on contrast enema is greater than 1 in patients with Hirschsprung's disease.

In patients with total colonic Hirschsprung's disease or with a longer segment involving the small bowel, the findings may not be as clear, and the transition zone may not be identified. The sigmoid– rectum ratio is not helpful.

A follow-up radiograph is obtained in 24 hours when the barium enema is inconclusive in a newborn with suspected Hirschsprung's disease. The appearance of residual barium in the bowel is very suggestive of Hirschsprung's disease.

Tissue confirmation

Biopsy specimens are examined for the presence of Auerbach's plexus in the muscular layer. The specimen can be obtained by either of two procedures.

Seromuscular biopsy of the bowel wall at laparotomy

Full -thickness transrectal biopsy, which requires general anesthesia

Suction biopsy technique is currently used as the first step.

With this procedure, the biopsy specimen is examined for Meissner's plexus in the submucosal layer.

The procedure can be performed at the bedside, with little risk to the patient.

Although the procedure is simple, it produces small specimens and requires an experienced pathologist for a correct interpretation.

Staining for acetylcholinesterase (which is increased in Hirschsprung's disease) may aid in the histologic diagnosis.

D Preoperative management

Once the diagnosis has been made, the patient is prepared for surgery. P.568

If enterocolitis is present preoperatively, the patient requires parenteral antibiotics and gastric decompression. In addition, rectal decompression and irrigations with saline or an antibiotic solution are performed.

The classic surgical approach is to perform a colostomy in an area of intestine that has ganglia cells.

Once the gastrointestinal tract is patent, the child can be fed orally.

E Operative management

There are a variety of different operative approaches for Hirshsprung's disease. Many surgeons will do a primary pullthrough at the time of diagnosis if the patient is stable. If not, a colostomy will need to be performed to relieve the obstruction and allow enteral feedings.

Goals of surgery. Although different operative procedures are available for the definitive repair, all have two goals in common:

Removal of most or all of the involved intestine

Re -establishment of a functional, continent gastrointestinal tract by bringing well-inervated intestine to the anus.

Procedures. The four most commonly performed are the Swenson, Duhamel, and Soave procedures, and the recently described transanal approach. These procedures can be performed in a tradional open fashion or laparoscopically assisted.

Swenson's procedure is the standard operation, but it is difficult to perform and is not used today by most pediatric surgeons.

The involved colon is excised to within 1 cm of the anal mucocutaneous margin.

The bowel is then sutured to the cuff of distal anorectal segment, thus establishing gastrointestinal continuity.

Duhamel procedure

The involved colon is excised to the level of the peritoneal reflection within the abdomen.

The proximal normal bowel is tunneled between the sacrum and the rectum and is then

anastomosed end -to -side to the low anorectum.

Soave procedure

In this operation, the involved colon is also excised to the level of the peritoneal reflection.

The mucosa is removed in the remaining rectum.

The proximal normal bowel is pulled through the stripped anorectal segment and is sutured to the anorectal junction.

Transanal approach

In this operation, the rectal mucosa is dissected from the rectal wall transanally up to the peritoneal reflection.

The abdomen is entered transanally through the rectal wall.

The proximal normal bowel is pulled through the stripped anorectal segment is and sutured to the anorectal junction.

Sequelae. Enterocolitis may occur after these operations because the internal sphcinter is still abonormally innervated. Because the mortality rate is high if untreated, early diagnosis and treatment are critical.

F

The prognosis for infants properly treated for Hirschsprung's disease is good.

Anal dilatation may be necessary intermittently if constipation occurs secondary to the retained aganglionic internal anal sphincter.

Problems of incontinence and fecal soiling occur occasionally.

Postoperative constipation may reflect a group of patients with poor gastrointestinal motility as a spectrum of the disease. These patients have responded to prokinetic agents. Recent studies have raised the question of poor neurotransmission as a problem with Hirschsprung's disease. However, if constipation persists, biopsy at the surgical anastomosis should be considered to document ganglion cells at this site.

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IX Disorders of Infancy

A Pyloric stenosis

In this condition, hypertrophy of the muscular layer of the pylorus causes gastric outlet obstruction. The classic symptom is nonbilious projectile vomiting.

The etiology of the condition is unknown. However, certain consistent elements imply a hereditary, genetic basis.

It is a male -predominant disease; the male:female ratio is 4:1.

The offspring of a female with pyloric stenosis have a 10 -fold greater chance of developing pyloric stenosis, whereas offspring of a male with pyloric stenosis have a four-fold greater chance of developing pyloric stenosis.

The condition is more common in whites than in blacks.

Clinical presentation. Pyloric stenosis occurs early in life, usually between the age of 2 weeks and 2 months.

The history is one of nonvomiting at birth, a gradual onset of vomiting, and final progression to nonbilious projectile vomiting.

Vomiting may lead to dehydration.

A hypochloremic, hypokalemic metabolic alkalosis may be present; this condition varies with the degree of dehydration.

Jaundice is present in 10% of the infants. It is thought to be caused by a deficiency of glucuronyl transferase and resolves after surgical treatment of the pyloric stenosis.

With the improvement of survival of premature infants with various other anomalies, a group of older (2–4 months of age) infants is developing pyloric stenosis. It is unclear whether this situation represents a delay in diagnosis because of parenteral feeding or a true older presentation. However, the diagnosis should be considered in this subgroup if feeding problems develop or persist.

Diagnosis

The physical examination can often provide the diagnosis.

Palpation of a midepigastric mass in the right upper quadrant of an infant with projectile vomiting is the sine qua non of pyloric stenosis. However, finding the mass may require experience, persistence, and patience.

Complete evacuation of the stomach by a nasogastric tube may aid in finding the mass.

Ultrasonography, however, has become the most common method of diagnosis due to the case of the study and “the lost art of physical exam.” Although the examination does not require a cooperative patient, it does rely on the experience of the person performing the study. The criteria for diagnosis are documented.

The length of the pylorus is measured; if greater than 15 mm, pyloric stenosis is suspected.

The width of the muscular wall is measured; if greater than 4 mm, pyloric stenosis is suspected.

Upper gastrointestinal series may be helpful in the diagnosis. The findings include:

Gastric retention of 3–4 hours

Elongation and narrowing of the antrum

A “string” sign or “railroad track” sign (one or two thin barium tracts, respectively, through the pylorus)

A mass effect on the antrum

Nonprogression of a peristaltic wave through the pylorus to the duodenum

Preoperative management

Correction of the alkalosis and volume deficits is necessary.

The conditions are corrected by fluid replacement and potassium supplementation.

Adequate hydration is determined by voiding patterns (the normal infant voids 4 to 5 times a day).

Alkalosis correction is measured by the serum bicarbonate, which should be less than 28 mEq/dL, or serum chloride, which should be greater than 92 mEq/dL before surgery is considered.

Nasogastric decompression may also be instituted to protect against aspiration and to aid in the quicker return of gastric motility in the postoperative period.

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Operative management. The surgical procedure is pyloromyotomy. This procedure involves an incision of the serosa over the pylorus and division of the hypertrophic muscle of the antrum but not the duodenum. The stomach is not entered.

Postoperative management

The patient may be started on feedings of glucose and water or an electrolyte infant formula (e.g., Pedialyte) 4–6 hours after surgery.

Vomiting occurs in 50%–80% of patients because of gastric atony or acute gastritis.

This vomiting is usually self-limited and has been decreased with preoperative gastric decompression.

Occasionally, the patient will benefit from gastric lavage with half -strength bicarbonate solution.

Feedings are advanced on a prescribed schedule, and full feedings are usually reached by 24 hours after surgery. The patient may be discharged at this point.

Complications

Duodenal perforation is the major complication.

Its danger is not so much its occurrence as the problem of its being overlooked at the time of surgery.

The perforation is handled by a simple repair, nasogastric decompression for 24–48 hours, and antibiotics.

If it is recognized and handled appropriately, the major difficulty is an extended hospital stay.

If the perforation is missed, the morbidity is severe, and the incidence of mortality is significant.

Apnea may also occur in the early postoperative period.

The patient should, therefore, have an apnea monitor in place for the first 24 hours postoperatively.

Postoperative apnea is associated with a serum carbon dioxide level greater than 28 mL/dL.

An incomplete pyloromyotomy may cause recurrent symptoms. This operation can be evaluated best with ultrasonography. Pyloric measurements decrease to normal 2–4 weeks after a complete pyloromyotomy.

Prognosis. Once adequately treated, pyloric stenosis does recur, and long-term studies indicate no sequelae such as ulcer disease, food intolerance, or hiatal hernia. In addition, no problems with growth and development occur.

B

Biliary atresia is a disease that affects the development of the biliary duct system both intra - and extrahepatically. It occurs once in every 25,000 births.

The etiology of the disease is unknown. Many possible causes have been implicated but not confirmed, including viral infections, hereditary factors, neonatal hepatitis, and malformation of the extrahepatic ductal system. Biliary atresia appears to develop after birth. Although isolated fetal cases have been described in Japan, no cases have been reported in the United States.

Types. Classically, biliary atresia is divided into correctable and uncorrectable types. However, the current belief is that biliary atresia represents a progressive spectrum of disease and that these divisions have little bearing on the eventual outcome.

Correctable biliary atresia occurs in 20% of the cases.

A normal common bile duct becomes atretic at some distal point.

It is called “correctable” because the duct can be anastomosed to a jejunal conduit.

Uncorrectable biliary atresia. No macroscopic biliary system is present in the portal triad. Until the Kasai operation, no procedure had been successful in establishing bile drainage of the liver.

Clinical presentation. Clinically, the child presents from 4 weeks to 4 months of age as a healthy but jaundiced infant with few other complaints. Some patients have associated light stools.

Laboratory studies show conjugated hyperbilirubinemia.

Liver function studies may or may not be abnormal, depending on the degree of liver damage from cholestasis.

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Diagnosis. The most important rule of thumb is that persistent jaundice beyond the first month of life must be evaluated. This condition may not affect the outcome in patients with medical causes of conjugated hyperbilirubinemia (for whom no effective therapy may exist). However, the prognosis of surgery for biliary atresia is related to the age at diagnosis.

The workup is designed to differentiate true anatomic obstruction of the biliary tree from other causes of hyperbilirubinemia.

TORCH (toxoplasmosis, o thers, rubella, cytomegalovirus, and h erpes simplex virus) titers are checked for possible infection.

Serum electrophoretic patterns are examined for α 1 -antitrypsin deficiency.

Ultrasonography is performed to identify the gallbladder and the fibrotic bile duct at the portohepatis. If the gallbladder is not seen or the fibrotic ducts are not located, an exploratory laparotomy should be strongly considered instead of further tests.

Nuclear scans using technetium 99m (99m Tc) -labeled iminodiacetic acid derivatives look for biliary excretion into the gastrointestinal tract. The accuracy of these tests may be enhanced with the administration of phenobarbital sodium (PBS). PBS stimulates liver enzymes and improves the excretion of bile in patients without biliary atresia.

Percutaneous liver biopsy is very helpful in experienced hands. If it shows bile duct proliferation in the face of hepatocellular necrosis, biliary atresia should be suspected.

If biliary atresia cannot be ruled out by these methods, the child should undergo a diagnostic laparotomy.

If an intraoperative cholangiography demonstrates a normal patent biliary system, a wedge biopsy of the liver is taken and the surgical procedure is ended.

If patency cannot be demonstrated, the porta hepatis is explored in an effort to find the atretic duct.

If an extrahepatic duct can be found, a Roux -en -Y loop of jejunum is anastomosed to it. This is the so-called correctable biliary atresia.

If the common duct cannot be found, the dissection is then carried to the hilus of the porta hepatis and a Kasai procedure (hepatoportal enterostomy) is performed. This involves anastomosing a loop of jejunum to the liver hilus, incorporating the area where the common bile duct should be.

Prognosis

Two factors influence the outcome of the Kasai operation:

At surgery, the patient is less than 10 weeks old.

The best results are obtained in patients 8–12 weeks old.

To date, there have been no long-term survivors among patients who had repairs done when they were more than 20 weeks old. This is caused by the irreversible liver damage that results from cholestasis.

The microscopic stage of the biliary tree is examined from the hilar dissection specimen.

Patients with ductules greater than 120 µm in diameter have a good prognosis.

Patients with ductules smaller than 70 µm have a very poor prognosis.

A “gray zone” occurs when the ductules are between 70 and 120 µm. Although bile

drainage may occur, resolution of the jaundice and reversibility of the liver disease may or may not occur.

Currently, approximately 60% of the patients with biliary atresia undergo a surgical repair.

However, only a little more than one half of these patients have a resolution of jaundice and a return to normal liver function.

One third of all patients with biliary atresia who undergo surgery will be treated successfully by current surgical techniques. (These results were obtained in the United States.)

Biliary atresia remains the primary indication for liver transplantation in the pediatric population.

More than 50% of the patients with failed hepaticoportenterostomies can be treated successfully with transplants. The limiting factor is the availability of donor organs.

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Recently, the use of split liver grafts has shown promise. This allows a donor liver to be anatomically divided and used in two recipients.

Living related liver transplants (using segments of the left lobe) have also been successful.

Because of these advancements, some transplant centers advocate transplant as the primary procedure.

C

Necrotizing enterocolitis (NEC) is an ischemic disorder of the intestine in the newborn.

Etiology. Although the etiology and underlying mechanism of NEC is not completely understood, it is probably multifactorial. Ischemic injury to an immature intestine in a host with an immature immune system in the presence of bacteria can result in NEC.

Clinical presentation

The basic defect is an ischemic or hypoxic insult, which causes intestinal mucosal sloughing. This may lead to bacterial invasion and subsequent intestinal gangrene and perforation.

The patients are usually born prematurely or have a low birth weight (75% weigh <2,000 g at birth). The disease usually occurs within the first 2 weeks of life.

The first signs are usually intolerance to formula and abdominal distention. These signs may be associated with the passage of either heme -positive or grossly bloody stools.

Associated perinatal problems include premature rupture of the membranes, prolonged labor, amnionitis, umbilical artery catheterization, respiratory distress, apneic episodes, cyanosis, or delivery -room resuscitation.

Diagnosis

Laboratory findings include leukopenia, thrombocytopenia, a low hematocrit, low serum sodium levels, metabolic acidosis, and coagulation defects.

Abdominal radiographs are used to aid in the diagnosis and to follow the patient's clinical course.

The initial findings include distended, edematous intestines; intramural air (pneumatosis); portal vein gas; an isolated persistent distended loop of bowel; or free intraperitoneal air, suggesting intestinal perforation.

Medical management. The primary management remains medical. This includes gastrointestinal decompression with a large oral or nasogastric tube, parenteral antibiotic therapy, treatment with fluids, and nutritional support.

Operative management. Although the disease is primarily a medical disorder, approximately 40% of all infants who develop necrotizing enterocolitis require surgery for its complications (e.g., perforation, gangrene, or intestinal stricture).

An absolute indication for surgery in the acute stage is intestinal perforation.

This perforation can usually be documented by the abdominal radiograph.

A cross-table lateral or left lateral decubitus position is used.

Films are obtained every 4–6 hours or as clinically indicated.

If perforation occurs, it is treated by resection of the involved intestine.

The gastrointestinal tract is diverted with either a jejunostomy or an ileostomy and colostomy.

Primary reanastomosis of the normal bowel is performed only in patients with limited disease or an isolated perforation.

In the severely ill patient with perforation or in the micropremature infant (<1,000 g), a major resective procedure may not be tolerated. In this situation, placement of peritoneal drains (using local anesthesia) at the bedside has proved successful. This can be either a stabilizing step or definitive therapy, depending on the clinical response of the patient.

Relative indications for surgery

Signs of peritonitis (erythema or edema of the abdominal wall) increase.

The patient fails to stabilize after 12 hours of optimal medical treatment (the patient shows persistent acidosis, apnea, or hypothermia).

A persistent distended loop of bowel is seen on serial radiographs.

An abdominal mass is palpated.

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A stricture with subsequent intestinal obstruction occurs in approximately 30% of cases.

This problem occurs usually 3–6 weeks after the acute episode.

Strictures are treated by resection and primary anastomosis once the patient is prepared nutritionally for surgery.

Postoperative management includes continued medical management of the primary disease as well as routine postsurgical care.

The infant is treated with antibiotics, gastrointestinal decompression, and hyperalimentation.

The disease may progress, requiring further surgery for additional perforations. Recurrent necrotizing enterocolitis occurs in approximately 4% of patients.

Oral feedings are not started until 10–14 days after the acute disease resolves. Dietary adjustments may be necessary until the mucosa has regenerated and undergone functional maturation.

The enterostomy can be closed during the initial hospitalization or later on.

Management of the stoma can be difficult.

Local problems include prolapse, degeneration of the surrounding skin, or mucosal irritation.

Physiologic problems include fluid losses, electrolyte abnormalities, and intolerance of the diet.

Early recognition and treatment of these difficulties are necessary to prevent further complications.

Prognosis

The mortality rate is 20% among patients who require only medical management for NEC.

The mortality rate among patients requiring surgery is up to 50%, reflecting the greater severity of the disease in this group.

Birth weight also affects outcome, and the overall mortality is 40% in patients weighing less than 1,500 g and 0%–20% in patients weighing more than 2,500 g.

Long-term morbidity is related to the quantity and function of the remaining intestine and other comorbidities related to prematurity after recovery from NEC.

A patient who has had an extensive bowel resection may develop a short-bowel syndrome (see Chapter 12, II E ) requiring a change of diet or nutritional support. This syndrome has been reported to occur in approximately 8% of all patients with NEC. However, NEC is the major cause of short-bowel syndrome in children (20%–50% of all patients).

Comorbidities include intraventricular cerebral hemorrhage, chronic pulmonary insufficiency, or associated cardiac problems.

X Solid Tumors

The two most common solid tumors of childhood are Wilms' tumor and neuroblastoma. Although other tumors occur (e.g., rhabdomyosarcoma, Ewing's tumor, osteogenic sarcoma, various brain tumors), neuroblastoma and Wilms' tumor illustrate the multidisciplinary approach that is currently used in the management of tumors that occur in childhood. They are also outstanding examples of successful management (Wilms' tumor) and the need for continued research to improve current poor results (neuroblastoma).

A

Wilms' tumor can involve either the entire kidney or a part of it. Bilateral involvement occurs in 3%–10% of the cases.

Etiology. Mesodermal, mesonephric, and metanephric origins have been proposed for this tumor.

Incidence. It has been estimated that 500 new cases of Wilms' tumor occur each year in the United States.

Clinical presentation

An asymptomatic flank mass is usually discovered by the parents or during a routine physical examination. The mass is smooth, lobulated, and commonly mobile.

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Other complaints or findings include abdominal pain, hematuria, and anorexia.

Hypertension occurs in approximately 10% of patients.

The patient is between 1 and 4 years of age at presentation; most patients are between 1 and 3 years of age.

The tumor rarely crosses the midline but may appear to cross because of its size.

Associated anomalies

Wilms' tumor has been associated with congenital anomalies, such as aniridia, hemihypertrophy, Beckwith's syndrome, sexual ambiguity, cryptorchidism, urinary tract anomalies, and abnormal karyotypes.

Congenital mesoblastic nephroma is a distinct renal tumor of infancy related to Wilms' tumor.

To date, approximately 70 cases have been reported.

The tumor usually presents soon after birth as an abdominal mass.

Nephrectomy alone is the current therapy and provides a cure.

Diagnosis. Imaging studies to aid in the diagnosis of Wilms' tumor should define the nature of the abdominal mass, the organ of origin, the status of the contralateral kidney, the presence of tumor in the renal vein or vena cava, and the presence or absence of distal metastases.

A chest radiograph will reveal metastasis to the lung, which is the most common site.

Ultrasonography with a Doppler examination can identify the organ of origin, the opposite kidney, and the presence of renal vein or vena cava involvement.

Venograms are useful if the ultrasound cannot define tumor involvement of the vena cava.

A computed tomography (CT) scan can identify both the tumor and lung metastasis, but the sensitivity for the metastasis is high and is not used currently in the staging of Wilms' tumor.

Staging of Wilms' tumor is as follows:

Stage I: The tumor is limited to the kidney and is completely excised. The surface of the renal capsule is intact. The tumor was not ruptured before or during removal. There is no residual tumor apparent beyond the margins of resection.

Stage II: The tumor extends beyond the kidney but is completely removed. There is regional extension of the tumor (i.e., penetration through the outer surface of the renal capsule into the perirenal soft tissues). Vessels outside the kidney substance are infiltrated or contain tumor thrombus. The tumor may have been biopsied, or there has been local spillage of tumor confined to the flank. There is no residual tumor apparent at or beyond the margins of excision.

Stage III: A residual nonhematogenous tumor is confined to the abdomen.

Lymph nodes on biopsy are found to be involved in the hulus, the periaortic chains, or beyond.

There has been diffuse peritoneal contamination by tumor, such as spillage or tumor beyond the flank before or during surgery or tumor growth that has penetrated through the peritoneal surface.

Implants are found on the peritoneal surface.

The tumor extends beyond the surgical margins either microscopically or grossly.

The tumor is not completely resectable because of local infiltration into vital structures.

Stage IV: Hematogenous metastases can occur with deposits beyond stage III (e.g., lung, liver, bone, or brain).

Stage V: Bilateral renal involvement is evident at diagnosis. An attempt should be made to stage each side according to the aforementioned criteria on the basis of the extent of disease before a biopsy.

Management of Wilms' tumor involves a multidisciplinary approach.

Surgery is the mainstay of treatment.

The timing of surgery depends on the stage of the tumor (i.e., stage IV or V).

The operation includes:

An exploratory laparotomy

Examination of the opposite kidney

Resection of the tumor

Periaortic node dissection or sampling

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Because of the relatively good prognosis, even with extensive disease, resection of other organs in an effort to remove the tumor is acceptable.

Venacaval extension requires the removal of the tumor thrombus. This operation may require a cardiopulmonary bypass to assist in the resection.

Chemotherapy currently involves the use of dactinomycin (actinomycin D) and vincristine.

Currently, chemotherapy is used in all stages (I–V) for varying cycles, depending on the histology (see X A 8).

Dactinomycin and vincristine are given preoperatively in stages IV and V disease.

Adriamycin is added to the chemotherapy regimen for patients with advanced disease.

Radiotherapy is used to treat extensive disease (stages III–V). The numerous complications after high-dose radiotherapy include secondary cancers in children; interference with growth and development of bones, joints, and muscles; radiation pneumonitis; radiation enteritis; and cardiotoxicity.

Prognosis. Survival appears to be related to the histology of the tumor, which is reported as favorable (FH) and unfavorable (UH) and dictates treatment protocols. Current 2-year survival rates by stage and histology are as follows:

Stage I (FH)—97%

Stage II (FH)—95%

Stage III (FH)—88%

Stage IV (FH)—85%

Stages I–III (UH) —80%

Stage IV (UH) —55%

Stage V —50%

B

Neuroblastoma is a neoplasm of adrenal and neural crest origin.

Incidence. It occurs in 1 of every 10,000 live births and is the most common extracranial solid tumor of childhood. It occurs in the early age group, with 50%–60% presenting by 2 years of age.

Types. The following are several major variants of neuroblastoma.

Classic neuroblastoma is a highly undifferentiated, immature malignant tumor that is unencapsulated and diffusely infiltrates the surrounding tissue.

Ganglioneuroma is a benign, well-encapsulated tumor containing fully differentiated mature ganglia cells.

Ganglioneuroblastoma is an intermediate or transitional form consisting of both primitive undifferentiated neuroblasts and mature differentiated ganglia cells. It can occur with or without encapsulation.

Etiology. Although they may occur anywhere along the sympathetic chain, the majority (65%) of these tumors arise from adrenal or nonadrenal retroperitoneal sites.

Clinical presentation

Most patients present with a complaint of an abdominal mass.

Neurologic symptoms may occur, resulting from compression of nerve trunks or from extension of the tumor into the extradural space (“dumbbell” tumor).

Horner's syndrome has been reported.

Other symptoms include acute cerebellar ataxia and opsoclonus (i.e., sustained, irregular multidirectional, spontaneous conjugate eye movements).

Metastatic spread can involve the liver, lungs, skin, bone marrow, and bone.

Skin lesions are firm, nontender, and bluish; a biopsy will provide the diagnosis.

The orbit is a common site of bony metastasis with consequent periorbital ecchymosis and proptosis.

More than 50% of patients have metastatic disease at presentation.

The diagnosis of the tumor may be obtained by various laboratory methods.

Bone marrow aspiration may reveal typical neuroblastoma cells.

Urinalysis. The tumor may synthesize various catecholamines.

The excretion products include vanillylmandelic acid (VMA) and homovanillic acid.

These acids can be checked in both spot urine samples and in 24 -hour urine collections. P.576

Radiologic studies

Skeletal surveys or bone scans may show metastatic lesions.

Chest radiographs will confirm or rule out pulmonary metastasis.

Ultrasonography acts as a screening tool to define the organ of origin and to rule out Wilms' tumor.

Calcifications are seen much more often on abdominal radiographs in neuroblastoma than in Wilms' tumor.

A CT scan gives complete details of the tumor as well as being sensitive to identifying metastatic disease.

If spinal cord extension of a paraspinal neuroblastoma, the presence of a “dumbbell” tumor, or neurologic symptoms are suspected, magnetic resonance imaging (MRI) is very helpful in defining the exact extent of cord involvement.

Liver function is documented, and routine blood studies are done. Anemia will be present in approximately 40%–60% of the patients at the time of diagnosis.

Age. The younger the child at diagnosis, the better will be the outlook; this variable is independent of staging.

Stage. The more advanced the disease, the worse will be the prognosis; however, stage D (S) has a relatively good prognosis (70% survival).

Location. An abdominal neuroblastoma has a worse outlook than has an extra-abdominal neuroblastoma.

Site of metastasis. Patients presenting with bony lesions have a mortality rate of almost 100%.

Presentation. Patients presenting with opsoclonus have a higher survival rate than do those who present without it.

Biologic markers are currently being used to define a study group as low risk in an effort to limit transplantation in order to reduce morbidity.

Overall survival rates are as follows:

Stage A—90%

Stage B—80%

Stage C—60%

Stage D—10%

Stage D (S)—70%

The two major pediatric cancer study groups (Pediatric Oncology Group and Children's Cancer Group) are currently merging into one unit. This merger will standardize study data and will result in an effort to improve therapy and general outcome.

Other studies now being undertaken in the long-term outcome for survivors relate to possible second malignancies and fertility as well as mental and physical development. These studies are confined not just to solid tumors but also to hematologic cancer.