Intrauterine fetal ureteral obstruction

British Association of Paediatric Urologists consensus statement on the management of the primary obstructive megaureter

INTRODUCTION

It is well-known that the majority of congenital megaureters may be managed conservatively, but the indications and surgical options in patients requiring intervention are less well defined. Hence this topic was selected for discussion at the 2012 consensus meeting of the British Association of Paediatric Urologists (BAPU). Our aim was to establish current UK practice and derive a consensus management strategy.

METHODS

An evidence-based literature review on a predefined set of questions on the management of the primary congenital megaureter was presented to a panel of 56 Consultant Surgeon members of the British Association of Paediatric Urologists (BAPU), and current opinion and practice established. Each question was discussed, and a show of hands determined whether the panel reached a consensus (two-thirds majority).

RESULTS

The BAPU defined a ureteric diameter over 7 mm as abnormal. The recommendation was for newborns with prenatally diagnosed hydroureteronephrosis to receive antibiotic prophylaxis and be investigated with an ultrasound scan and micturating cystourethrogram, followed by a diuretic renogram once VUR and bladder outlet obstruction had been excluded. Initial management of primary megaureters is conservative. Indications for surgical intervention include symptoms such as febrile UTIs or pain, and in the asymptomatic patient, a DRF below 40% associated with massive or progressive hydronephrosis, or a drop in differential function on serial renograms. The BAPU recommended a ureteral reimplantation in patients over 1 year of age but recognized that the procedure may be challenging in infancy. Proposed alternatives were the insertion of a temporary JJ stent or a refluxing reimplantation.

CONCLUSION

A peer-reviewed consensus guideline for the management of the primary megaureter has been established. The guideline is based on current evidence and peer practice and the BAPU recognized that new techniques requiring further studies may have a role in future management.

[Primary megaureter]

A primary megaureter is an anomaly with a prevesical or overall dilated ureter of more than 6 mm in diameter. It is important to distinguish between cases of primary non-refluxing and primary obstructive-refluxing megaureters, as the treatment of both is completely different. The basic diagnostic work-up includes ultrasonography and voiding cystourethrography. Diuretic renography is used to detect split renal function and the degree of upper urinary tract obstruction. In most cases of primary non-refluxing megaureter surgical treatment is unnecessary due to the high remission rate, whereas obstructive refluxing megaureters commonly only need to be corrected. Antibiotic prophylaxis may be indicated in infants with a primary obstructive megaureter during the first 6 months of life due to a higher risk of complications due to pyelonephritis especially in this age group.

Concomitant endoureterotomy and dextranomer/hyaluronic acid subureteral injection for management of obstructive refluxing megaureter

PURPOSE

To present the results of our experience with combined endoureterotomy and endoscopic injection of dextranomer/hyaluronic acid (Deflux) for the treatment of primary obstructive refluxing megaureter (PORM).

PATIENTS AND METHODS

Eighteen children (12 female, 6 male; mean age-14 months) with 20 PORM units underwent concomitant endoureterotomy and endoscopic subureteral Deflux injection. All patients underwent endoureterotomy at the 6-o'clock position with insertion of a 3F Double-J ureteral stent into the obstructed segment of ureter and subureteral injection of Deflux at the 5-o'clock and 7-o'clock positions. The Double-J stent was left in place with its distal tip fixed with a single knot to the external genitalia for easy removal after 1 week. Patients with refluxing nonobstructive ureter on the contralateral side of the PORM unit (seven children) underwent simultaneous endoscopic subureteral injection of Deflux. Voiding cystourethrography (VCUG) was performed at 6 months, and ultrasonography was performed at 1 week 3, 6, and 12 months postoperatively.

RESULTS

With a mean follow-up of 30 months, the procedure was uneventful in all patients. Follow-up VCUG showed no evidence of reflux in 15 ureterorenal (75%), significant decrease in reflux grade in 2 (10%), and no change in 3 (15%) in the endoscopic treated PORM units. No evidence of reflux was observed in the treated contralateral refluxing nonobstructive ureters. Ultrasonography revealed no ureterovesical junction obstruction. In 19 ureterorenal (95%) units, there was a complete resolution or decrease in hydroureteronephrosis.

CONCLUSIONS

The results of this study demonstrate that combined endoureterotomy and subureteral injection of Deflux is safe and effective in the treatment of PORM in selected patients.

The utilization of stents in the management of primary obstructive megaureters requiring intervention before 1 year of age

OBJECTIVE

To analyse the long-term outcome of 16 infants with primary obstructive megaureter managed by (endoscopic or open) stenting over a 10-year period.

METHODS

A retrospective case-note and imaging review was performed between 1997 and 2007. Data are presented as medians (range) and were compared using the Mann-Whitney test.

RESULTS

Sixteen infants with 19 obstructed megaureters were stented at a median age of 24 weeks, for a median of 6 months. One-third of stents were inserted endoscopically. Complications (stent migration, stone formation or infection) occurred in 31.6%. One infant was excluded due to a co-existent pelviureteric junction obstruction. Drainage improved in 10 ureters (56%) following stent removal. Of the remaining renal units, 6 were reimplanted, and 2 underwent a nephrectomy due to deterioration in renal function following stent removal. Resolution of the vesicoureteric junction obstruction occurred in 4 of 6 infants following endoscopic stent insertion, and in 6 of 12 infants following open stent insertion (P=0.60). There was no difference in the length of time that ureters were stented in the resolved (7.5 (6-15) months) versus the reimplanted (6.0 (1-18) months) group (P=0.13).

CONCLUSIONS

Of obstructive megaureters managed by stenting for a median of 6 months, 56% did not require further surgery. However, morbidity occurred in one third of patients, and function deteriorated after removal of stent in two patients who later required a nephrectomy.

Maternal cocaine use and genitourinary tract malformations

A specific fetal disruption syndrome associated with maternal cocaine use has not as yet been documented. In the first 23 pregnancies evaluated in our program for chemically dependent women, one infant with prune belly syndrome and one infant with hypospadias were delivered to cocaine-using women. In the present study, all infants delivered in our program received a renal ultrasound at 2-3 days of life. Fifty infants born to cocaine-using women (group I) and 30 born to polydrug, noncocaine-using women (group II) were evaluated. The two groups of women were similar for age, gravidity, and race. Mean birth weight of the infants in the two groups was similar. Seven infants in group I demonstrated genitourinary tract malformations while there were no infants with such malformations in group II. It is hypothesized that the vasoconstrictive effects of cocaine could explain the abnormalities of the genitourinary tract found in the cocaine-exposed infants.

The ureterovesical junction

The ureterovesical junction was studied by dissection and serial sections in 50 post mortem specimens. Three points are considered in this paper: the structure of the terminal ureter, the anatomical arrangement of the ureteral hiatus and the ureteral sheath. Study of the structure of the intramural segment of the ureter demonstrated on one hand, the perfect continuity of the terminal ureter with the trigone and on the other hand, the abundance of the fibroelastic connective fibers which like the muscle fibers run longitudinally. The compliance of the intravesical ureter is dependent on the balance between these two components. The modification of this balance can lead to the creation of a functional obstacle. The anatomical arrangement of the ureteral hiatus is described. The inner muscle layer of the detrusor extends almost to the ureteral orifice, the truly submucosal part of the ureter thus being very small. The constitution of the ureteral orifice and its relations to the ureter account for the different positions of juxtaureteral diverticula and transhiatal herniae of the bladder mucosa. The many descriptions of the ureteral sheath appearing in the literature are reviewed in light of the findings from the present study. The juxtavesical segment of the ureter is surrounded by a fibroconjunctive sheath which fixes the ureter to the bladder wall. The transparietal segment of the ureter is ensheathed in its adventitia, whereas a fibromuscular sheath cannot be truly individualized over this ureteral segment.

The adynamic terminal ureteral segment

Recently, we observed hydroureteronephrosis owing to an adynamic transmural distal ureteral segment associated with a thickened bladder, consequent to bladder outlet obstruction. Histological examination disclosed a loss of intrinsic musculature of the terminal ureteral segment with fibrosis. The importance of this entity is in the fact that upper tract dilatation and deterioration may progress, despite apparently successful correction of the bladder outlet uropathy.