7.6 Treatment and Prognosis

–Reflux and obstruction may coexist in a small proportion of patients; in such instances, the reflux is often the most obvious finding and concomitant obstruction may not be considered unless the possibility of a dual lesion is considered.

–If a delayed film is obtained after the VCUG, poor drainage of one or both upper tracts may suggest associated VUJ obstruction.

–This can be confirmed or excluded by further evaluation.

–The final and most difficult step in the diagnosis is to differentiate between an obstructed and unobstructed megaureter.

–Tests such as renal scintigraphy, Doppler ultrasonography (DUS) and pressure-flow studies (the Whitaker test) are useful investigations.

•The diagnosis in most cases is only possible by repeated investigations and comparivng changes of the variables during a longer follow-up.

•The Whitaker test:

–The Whitaker test is currently rarely used in the diagnosis of children with megaureter.

–It is invasive, does not measure function, submits the collecting system to unphysiological rates of flow and has a variable correlation with functional studies such as the diuretic renogram.

7.6Treatment and Prognosis

•Increasing reports show that a considerable number of children with VUR or megaureters without reflux or obstruction may demonstrate improved renal function on radiography follow-ups, without surgical intervention.

•Nonoperative treatment however, requires close follow-up of patients with VUR or non- obstructed/non-refluxing megaureters.

•Nonoperative management of VUR and nonobstructed primary megaureter includes:

–Antimicrobial prophylaxis

–Treatment of voiding dysfunction

–Follow-up regular imaging studies to assess renal growth, renal scarring, and possible resolution of pathology.

•Current recommendations for antibiotic prophylaxis in all patients with VUR include:

–Antibiotic prophylaxis for children younger than 1 year with VUR and a history of febrile UTI, based on greater morbidity from recurrent UTI in this population.

–The use of antibiotic prophylaxis in older children with VUR should be made on an individualized basis.

–The use of antibiotic prophylaxis is most beneficial in:

•Those with grade 3 or greater VUR

•Girls

•Those with a significant history of recurrent febrile UTIs

•Those with bowel or bladder dysfunction

•Usually primary megaureter is asymptomatic and requiring no treatment.

•If complications occur or the degree of obstruction is marked then re-implantation following resection of the aganglionic segment may be performed.

•Megaureter secondary to severe VUR or obstruction is usually managed with ureteral reimplantation.

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

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

•Most megaureters will require tapering.

•The ureteral caliber can be reduced by:

–Excising the distal redundant ureter (Hendren technique)

–Plication (Kalicinski technique, Starr technique)

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

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

•The treatment of primary megureter depends on the type:

•Refluxing primary megaureter:

–With the advent of antenatal ultrasound the management of refluxing primary megaureters changed in the past few years.

–The previous recommendation for surgery in newborns and infants with grades 4 and 5 reflux is obsolete.

–Medical management is appropriate during infancy and is continued if there is a trend to resolution.

–Surgery is recommended for persistent high-grade reflux in older children.

•Nonrefluxing unobstructed primary megaureter:

–Most patients who present with primary megaureter, particularly older children, clearly have the unobstructed variety.

–Most of these patients remain asymptomatic without surgery, and expectant management results in an improvement in the degree of urinary tract dilatation and no deterioration of renal function.

–This requires regular follow-up with antibiotic prophylaxis for urinary tract infections.

•Obstructed primary megaureter:

–Many cases of primary megaureter diagnosed antenatally resolve spontaneously within the first 2 years of life, with the maturation of the urinary tract.

–These are called ‘primary dilated megaureter’ by some authors to differentiate them from the real obstructive ones.

–The presence of significant obstruction is an indication for early surgical correction to preserve renal function.

–The goals of early surgery are:

•To minimize renal damage from obstruction

•To maximize the growth potential of the affected kidney

•To prevent complications of primary megaureter, especially infection and stone formation.

–However, presently there is no ideal method for assessing urinary tract obstruction, particularly in neonates and infants.

–Therefore, the therapeutic recommendations for neonates with obstructed primary megaureter remain controversial.

–During the past 10 years there has been an increasing trend towards conservative management.

–In this approach of conservative management:

•The patients are closely monitored including their symptoms

•Imaging follow-up

•Antibiotic prophylaxis

–The frequency of imaging decreases as the urinary tract dilatation stabilizes.

–Renal function is best assessed by renal scintigraphy

–Antibiotic prophylaxis must be begun routinely soon after delivery in infants with prenatally detected hydroureteronephrosis.

–Prophylaxis is continued after confirming the diagnosis of an obstructed primary megaureter.

–When surgical repair is undertaken prophylaxis is continued until the obstruction is relieved and no reflux is detected.

–The commonly used antibiotics for prophylaxis are:

•Amoxicillin (15 mg/kg) once a day for infants <2 months

•Trimethoprim (2 mg/kg) once a day for infants and children

–Surgery is indicated in cases of:

•Significant impairment to urine flow

•Persistent pain

•Pyelonephritis

•Calculi

•A decrease in renal function

•Principles of surgical treatment (Figs. 7.28, 7.29, 7.30, 7.31, and 7.32):

–The ureter is mobilized as for reimplantation for VUR.

–Resection of the distal ureter only is rarely sufficient to permit reimplantation.

–Reduction of the caliber of the distal ureter is necessary.

–Two methods can be used to remodel megaureters.

•Hendren technique: Excision of the distal severely dilated and redundant ureter or those that are markedly thickened.

•Plication (Kalicinski technique, Starr technique): Plication of the distal ureter is used when there is less dilatation, but may produce a bulky and stiff ureteric segment.

–Nonetheless, the frequency of postoperative reflux is no different between these methods.

–In the past, reduction of the caliber of the distal and mid ureter was done, but

currently reduction is limited to a section of ureter necessary to achieve an adequate length of intravesical tunnel.

–Remodelled megaureters have generally been reimplanted using:

•The standard Cohen cross-trigonal reimplantation

•The Leadbetter-type reimplantation

•The extravesical submucosal tunnel repairs

•The extravesical seromuscular tunnel repair

7.7Complications

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

•The success in reimplanting remodelled megaureters, regardless of technique, is not as high as with undilated ureters.

•Furthermore, in the neonatal period the complication rate is higher for reimplantation of a dilated ureter, especially into a small bladder.

•The reported rate of reoperation for reflux or obstruction is about 12 %.

•The major complications are:

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

–VUR (approximately 10 %)

–Diverticular formation

–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.

•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).

•Careful assessment of voiding symptoms and a low threshold for urodynamic studies are crucial in the evaluation of patients with recurrent VUR.

•A renal ultrasound should be obtained following surgical correction of VUR to assess for obstruction.

•Because of the very high success rate of open ureteral reimplantation, a postoperative VCUG is performed only in select cases.

•Concomitant ipsilateral PUJ obstruction can be seen in infants with obstructive primary megaureter.

–The preoperative diagnosis of both pathological conditions may be difficult.

–When PUJ obstruction is present, the ipsilateral ureter is seldom seen on IVU.

–The diagnosis is not made until a retrograde ureterogram is taken when the child is under anaesthesia for a pyeloplasty or when the ureter is seen to be dilated at the time of the pyeloplasty.

–A preoperative renal scan is more helpful in this regard, as the obstructed ureter usually fills and is visualized as the obstructed pelvis drains.

Further Reading

1. Anderson CB, Tanaka ST, Pope 4th JC, Adams MC, Brock 3rd JW, Thomas JC. Acute pain crisis as a presentation of primary megaureter in children. J Pediatr Urol. 2011;8:254–7.

2. Baskin LS, Zderic SA, Snyder HM, Duckett JW.

J Urol. 1994;152:618.

4. Cooper CS. Diagnosis and management of vesicoureteral reflux in children. Nat Rev Urol. 2009;6(9): 481–9.

5. DeFoor W, Minevich E, Reddy P, Polsky E, McGregor A, Wacksman J. Results of tapered ureteral reimplantation for primary megaureter: extravesical versus intravesical approach. J Urol. 2004; 172(4 Pt 2):1640–3; discussion 1643.

6. Di Renzo D, Aguiar L, Cascini V, et al. Long-term follow-up of primary non-refluxing megaureter. J Urol. 2013;190:1021.

7. Farrugia MK, Hitchcock R, Radford A, et al. British Association of Paediatric Urologists consensus statement on the management of the primary obstructive megaureter. J Pediatr Urol. 2014;10:26.

8. Fretz PC, Austin JC, Cooper CS, Hawtrey CE. Longterm outcome analysis of Starr plication for primary obstructive megaureters. J Urol. 2004;172(2):703–5.

9. García-Aparicio L, Rodo J, Krauel L, et al. High pressure balloon dilation of the ureterovesical junction – first line approach to treat primary obstructive megaureter? J Urol. 2012;187:1834.

10. Gimpel C, Masioniene L, Djakovic N, Schenk JP, Haberkorn U, Tönshoff B. Complications and longterm outcome of primary obstructive megaureter in childhood. Pediatr Nephrol. 2010;25(9):1679–86.

11.Gimpel C, Masioniene L, Djakovic N, et al. Complications and long-term outcome of primary obstructive megaureter in childhood. Pediatr Nephrol. 2010;25:1679.

12.Lee SD, Akbal C, Kaefer M. Refluxing ureteral reimplant as temporary treatment of obstructive megaure-

ter in neonate and infant. J Urol. 2005;173(4):1357–60; discussion 1360.

13. Liu HY, Dhillon HK, Yeung CK, et al. Clinical outcome and management of prenatally diagnosed primary megaureters. J Urol. 1994;152:614.

14. Massad C, Megaureter SE, Gonzales ET, Bauer SB, editors. Pediatric urology practice. Philadelphia: Lippincott Williams & Wilkins; 1999. p. 205.

15. McLellan DL, Retik AB, Bauer SB, et al. Rate and predictors of spontaneous resolution of prenatally diagnosed primary non-refluxing megaureter. J Urol. 2002;168:2177.

16. Renjen P, Bellah R, Hellinger JC, Darge K. Pediatric urologic advanced imaging: techniques and applications. Urol Clin N Am. 2010;37(2):307–18.

17.Shokeir AA, Nijman RJ. Primary megaureter: current trends in diagnosis and treatment. BJU Int. 2000;86(7): 861–8.

18.Shukla AR, Cooper J, Patel RP, et al. Prenatally detected primary megaureter: a role for extended followup. J Urol. 2005;173(4):1353–6.