commonly used, the extravesical approach (detrusorrhaphy) preserves the integrity of the bladder lumen and does not require a ureteral anastomosis. Extravesical reimplantation has been shown to decrease postoperative hematuria, minimize bladder spasms, reduce the need for urethral catheter, and shorten hospital stay. Of note, transient cases of urinary retention have been reported with bilateral extravesical ureteral reimplant. Although open ureteral reimplantation remains the gold standard, minimally invasive techniques (robotic assisted ureteral reimplantation) have demonstrated comparable success rates.

•Complications of ureteral reimplantation are uncommon.

•The most common technical complications are ureteral obstruction, persistent reflux, and diverticula formation.

•Ureteral reimplantation for mega ureter repair is a very safe, reproducible, and successful procedure.

•The major complications are the development of ureteral obstruction (2–5 %) or VUR (approximately 10 %).

•Ureteral obstruction is most likely the result of ureteral ischemia and subsequent fibrosis of an excisionally tapered segment.

•Initial management of this complication is percutaneous or endoscopic dilatation and stenting of the stricture, but many such instances ultimately require open surgical revision.

•If postoperative VUR is encountered, a reasonable treatment option is observation and antibiotic prophylaxis because many reflux cases resolve spontaneously.

•In addition, VUR is more likely to recur following reimplantation in cases in which bladder pressures are elevated (e.g. patients with untreated neuropathic bladders or voiding dysfunction).

•Treatment of bladder/bowel dysfunction is indicated, preferably prior to surgical intervention of VUR. Careful assessment of voiding symptoms and a low threshold for urodynamic studies are crucial in the evaluation of patients with recurrent VUR.

•Cases of high-grade VUR are less likely to spontaneously resolve and more likely to put the kidney at risk of scarring due to pyelonephritis.

•Prevention of infection is essential to minimize the risk of renal damage; therefore, continuous antibiotic prophylaxis is usually used in children with high-grade VUR while awaiting spontaneous resolution.

•Robotic-assisted ureteral reimplantation has gained popularity and will continue to evolve with time, although open ureteral reimplantation currently remains the criterion standard for surgical management of VUR.

•Antibiotic prophylaxis for all children with VUR remains controversial, although it is recommended in children younger than 1 year with a history of febrile UTI or grade III reflux or higher.

•Bowel and bladder dysfunction are often associated with VUR and increase the risk of pyelonephritis, so should be evaluated and treated aggressively in children with VUR.

6.8Mega Ureter

•The term mega ureter refers to an enlarged ureter.

•A mega ureter is a wide ureter, greater than 7 mm in diameter (Fig. 6.40).

•Light microscopy of mega ureters demonstrates a predominance of circular smooth muscle; muscle fiber hypoplasia and atrophy, with collagen deposits separating the muscle cells; and mural fibrosis with scant muscle fibers.

•Electron microscopy of mega ureters demonstrates increased collagen deposition within the adynamic segment.

•Megaureters may be classified into the following four categories:

–Obstructed

–Refluxing

–Obstructed and refluxing

–Nonobstructed/nonrefluxing

•Each of these categories is further divided into:

–Primary

–Secondary

Fig. 6.40 Intravenous urography showing a right mega ureter secondary to uretero-vesical junction obstruction

Classification of Mega Ureter

•Primary

•Secondary

Mega ureters are also classified into:

•Obstructive

•Reflexing

•Obstructed and refluxing

•Nonobstructed/Nonrefluxing

•This is based on their etiology, either intrinsic or extrinsic.

•Bilateral involvement is present in about 20% of patients with primary obstructed mega ureters.

•Primary obstructed mega ureter has a male-to- female ratio of nearly 4:1.

•The left side is more often affected than the right.

•Primary obstructed mega ureter:

–This is most commonly caused by an adynamic juxtavesical segment of the ureter

that fails to effectively propagate urine flow (Figs. 5.41 and 5.42).

•Secondary obstructed mega ureter:

–This occurs usually when ureteral dilatation is the result of a functional ureteral obstruction associated with elevated bladder pressures secondary to PUV or a neurogenic bladder that impedes ureteral emptying.

•Primary refluxing mega ureter:

–This is associated with severe VUR that alters ureteral efficiency by ureteral distention.

–The megaureter-megacystis syndrome is an extreme form of the primary refluxing mega ureters in which massive reflux prevents effective bladder emptying because urine is passed back and forth between the ureters and bladder.

•Secondary refluxing mega ureter:

–This occurs secondary to PUV or neurogenic bladder when elevated bladder pressures cause decompensation of the uretrovesical junction.

•Primary nonrefluxing/nonobstructed mega ureter:

–This is diagnosed when no evidence of obstruction or reflux can be demonstrated.

•Secondary nonrefluxing/nonobstructed mega ureter:

–This occurs secondary to diabetes insipidus, in which high urinary flow rates may overwhelm the maximum transport capacity of the ureter by peristalsis or as the result of ureteral atony accompanying a gram-negative UTI.

•Primary refluxing obstructed mega ureter:

–This occurs in the presence of an incompetent VUJ that allows reflux through an adynamic distal segment.

•Indications for surgical interventions:

–Increasing hydroureteronephrosis

–Decrease in renal function of involved kidney

–Development of UTI or recurrent pain

•Increasing experience shows that a considerable number of children with mega ureters without reflux or obstruction may demonstrate improved renal function on radiography, without surgical intervention.

•Nonoperative treatment mandates close followup care in patients with nonobstructed/nonrefluxing mega ureters.

•Nonoperative management of nonobstructed primary mega ureter includes antimicrobial suppression, treatment of voiding dysfunction, and regular imaging studies to assess renal growth, renal scarring, and possible resolution of pathology.

•Mega ureter secondary to severe VUR or obstruction is usually managed with ureteral reimplantation (Figs. 6.43, 6.44, 6.45, and 6.46).

•Reimplantation techniques are similar to those used for correcting primary VUR.

•The mega ureter can be mobilized via an intravesical, extravesical, or combined approach.

•Most mega ureters will require tapering.

•The ureteral caliber can be reduced by excising the distal redundant ureter (Hendren technique) or plication (Kalicinski technique, Starr technique) to achieve a satisfactory antireflux mechanism.

•Occasionally, the function of the kidney drained by a mega ureter is severely impaired, and nephroureterectomy may be necessary.

•There have been reports of obstructive mega ureters treated successfully by endoscopic dilation.

•Complications of ureteral reimplantation are uncommon.

•The most common technical complications are ureteral obstruction, persistent reflux, and diverticula formation.

•Ureteral reimplantation for mega ureter repair is a very safe, reproducible, and successful procedure.

•The major complications are:

–The development of ureteral obstruction (2–5 %)

–VUR (approximately 10 %).

•Ureteral obstruction is most likely the result of ureteral ischemia and subsequent fibrosis of an excisionally tapered segment.

•With respect to primary mega ureters, as in the case of VUR, spontaneous resolution is common.

•In the case of the obstructed primary mega ureter, spontaneous resolution is less likely to occur; however, a study reported a 70 % spontaneous regression.

Figs. 6.43 and 6.44 Clinical intraoperative photographs showing megaureters secondary to a stenosed adynamic lower ureteric segment. Note the diameter of the stenosed

Figs. 6.45 and 6.46 Clinical intraoperative photographs showing megaureters secondary to a stenosed adynamic lower ureteric segment. Note the diameter of the stenosed

Further Reading

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2. Adorisio O, Elia A, Landi L, Taverna M, Malvasio V, Danti AD. Effectiveness of primary endoscopic incision in treatment of ectopic ureterocele associated with duplex system. Urology. 2011;77(1):191–4.

3. Avni FE, Nicaise N, Hall M, et al. The role of MR imaging for the assessment of complicated duplex kidneys in children: preliminary report. Pediatr Radiol. 2001;31(4):215–23.

segment of the lower ureter. Note also the dilated ureter proximal to the stenotic segment

segment of the lower ureter. Note also the dilated ureter proximal to the stenotic segment

4. Bansal D, Cost NG, Bean CM, Noh PH. Pediatric laparo-endoscopic single site partial nephrectomy: feasibility in infants and small children for upper urinary tract duplication anomalies. J Pediatr Urol. 2014;10(5):859–63.

5.Bayne AP, Roth DR. Dextranomer/hyaluronic injection for the management of vesicoureteric reflux in complete ureteral duplication: should age and gender

be factors in decision making? J Endourol. 2010; 24(6):1013–6.

6. Blyth B, Passerini-Glazel G, Camuffo C, et al. Endoscopic incision of ureteroceles: intravesical versus ectopic. J Urol. 1993;149(3):556–9; discussion 560.

7. Bruno D, Delvecchio FC, Preminger GM. Successful management of lower-pole moiety ureteropelvic

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8. Byun E, Merguerian PA. A meta-analysis of surgical practice patterns in the endoscopic management of ureteroceles. J Urol. 2006;176(4 Pt 2):1871–7; discussion 1877.

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JJ.Single-system ectopic ureter: a 15-year review. Pediatr Surg Int. 2001;17:638.

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