Chapter 26. Unique Considerations in the Neonate and Infant |
243 |
Ninety-five percent of term neonates pass meconium within the first 24 h and almost all by 48 h. Premature babies may have delayed passage of meconium. A neonate born in meconium-stained liquor has passed meconium but beware of green stained liquor. This may represent fetal vomiting of green bile into the amniotic fluid and therefore obstruction.
Neonates who may pass meconium but who may still have bowel obstruction include:
1.Babies with Hirchsprung’s may pass meconium, especially after rectal examination
2.Some sticky meconium pellets may be passed in meconium ileus
3.Onset of symptoms in malrotation with volvulus may be delayed for some time after birth3
4.A missed anorectal malformation with a fistula
26.3 Initial Management
At this stage the diagnosis may or may not be known but there are certain management steps that are common to all neonates with bilious vomiting:
Initial management
Pass a nasogastric tube |
Commence iv fluids |
|
• |
8 or 10 Fr in a term baby |
Commence iv antibiotics |
• |
Aspirate and leave on free |
• as per local guidance |
|
drainage |
|
(Septic screen ± lumbar puncture)
26.4 Causes of Neonatal Bilious Vomiting
The following is a (non-exhaustive) list of causes of bilious vomiting in the neonate. If a malrotation with volvulus is missed then the consequences, i.e., dead midgut, are disastrous and it is for this reason that any child with bilious vomiting should be referred urgently to a pediatric surgeon.
244 |
|
R.T. Peters and S.S. Marven |
|
|
Causes |
|
|
||
Medical |
High obstruction |
|||
• |
Necrotizing enterocolitis |
• |
Malrotation ± volvulus |
|
• |
Sepsis |
• |
Duodenal atresia/stenosis |
|
|
– |
Urinary tract infection |
• |
Proximal jejunal atresia |
|
– |
Meningitis |
|
|
|
– |
Group B streptococcus |
Low obstruction |
|
• |
Raised intracranial pressure |
• |
Hirschsprung’s disease |
• |
Hypothyroidism |
• |
Ileal/colonic atresia |
• |
Prematurity |
• |
Anorectal malformation |
• |
Idiopathic bilious vomiting |
• |
Meconium ileus |
|
|
• |
Meconium plug |
|
|
|
syndrome |
|
|
• |
Small left colon |
|
|
|
syndrome |
|
|
• |
Hernia |
|
|
|
|
26.5 Malrotation With/Without
Midgut Volvulus
Malrotation is failure of the gut to complete anti-clockwise rotation resulting in the entire small bowel lying attached by a narrow stalk rather than a broad based mesentery to the posterior abdominal wall. It is therefore prone to twist around on this stalk which compromises the blood supply (superior mesenteric vessels) of most of the small bowel - a midgut volvulus. Up to 80% of cases of malrotation present in the first month of life and most of these in the first week.4 Therefore a previously apparently normal neonate (or child of any age) can present with a midgut volvulus. This is one of the reasons for urgency of referral
Chapter 26. Unique Considerations in the Neonate and Infant |
245 |
in bilious vomiting. If a midgut volvulus is missed then the entire midgut can become unviable. At best this leads to short gut and lifelong parenteral nutrition, at worst, death. Plain abdominal x-ray may show dilated stomach and proximal duodenum but may also be entirely normal in malrotation. The diagnostic modality of choice is an upper GI contrast study. This demonstrates the duodenal-jejunal flexure lying to the right of the spine and inferior to the duodenal bulb. Treatment involves urgent laparotomy with resection of any dead gut and Ladd’s procedure (Figs. 26.2 and 26.3).
FIGURE 26.2. Upper gastrointestinal contrast study demonstrating malrotation. The duodenal-jejunal flexure lies to the right of the spine.
246 R.T. Peters and S.S. Marven
FIGURE 26.3. Dead gut found at operation for malrotation with midgut volvulus.
26.6 Necrotizing Enterocolitis
This is almost exclusively a disease of preterm infants (although it can occur at term) and is therefore uncommon outside of the neonatal unit. Necrotizing enterocolitis (NEC) consists of bowel wall inflammation and ulceration which may proceed to perforation. Neonates present generally unwell with apneas and bradycardias, green vomiting and temperature instability. The abdomen may be distended and shiny or erythematous and there may be rectal bleeding. Abdominal radiograph features include distended bowel loops, intramural gas (pneumatosis intestinalis), portal vein gas and pneumoperitoneum. Management is mostly undertaken by the neonatology team and consists of stopping enteral feeds, a nasogastric tube on free drainage and antibiotics. Complicated NEC may require surgical intervention including perforation and stricture formation. Mortality for NEC with perforation remains between 30% and 50%.5