Congenital Bladder Diverticulum in a Neonate Simulating Posterior Urethral Valves

Primary bladder diverticulae are rare anomalies of the bladder. They usually present with recurrent urinary tract infections and dysuria. We present a case of retrovesical diverticulum, which presented with urinary retention behaved like a case of posterior urethral valves. A high index of suspicion and a well performed micutrating cystourethrogram helps in clinching the diagnosis. Excision of these diverticulae with or without ureteric reimplant is curative in most cases.


INTRODUCTION
Neonatal bladder outlet obstruction (BOO) is a well-recognized entity.Most commonly, it is associated with posterior urethral valves (PUV).Rarely, other space-occupying lesions in the pelvis, like a rectal duplication cyst, might impinge on the bladder neck and urethra and cause BOO [1].Primary congenital bladder diverticula (PCBD) are rare and usually present with urinary tract infections (UTIs).We report a case of congenital bladder diverticulum causing BOO in a neonate.

CASE REPORT
A 15-day-old, term born male, with an uneventful perinatal period, presented to the emergency with a history of progressive abdominal distention for 3 days and poor urinary stream.Abdominal ultrasound revealed bilateral hydroureteronephrosis (HUN) and a grossly distended posterior urethra (4 cm × 3 cm).Serum urea and creatinine at presentation were 70-3.0 mg%, respectively, with arterial blood gases showing metabolic acidosis.A provisional diagnosis of PUV was made.The baby was catheterized, and antibiotic treatment was initiated.Post-catheterization, the serum urea, and creatinine normalized to 17-0.2 mg%, respectively, within 5 days.The metabolic acidosis was corrected.Micturating cystoure-throgram (MCU), however, ruled out PUV; it showed a normal capacity bladder with multiple diverticula (Figure 1).The largest diverticulum, measuring 3.1 cm × 2.7 cm, was seen arising from the posterolateral wall of the bladder on the right side.The right ureter was seen draining into it.This was associated with Grade III vesicoureteral reflux on the right side.Post-void film revealed moderate amount of residual urine in the diverticulum.
The patient was taken up for surgery after fluid and electrolyte correction and optimization of renal functions.Intraoperatively, a large retrovesical diverticulum was seen pressing onto the bladder neck.Excision of the bladder diverticulum with a Paquin's right ureteric reimplantation was done.Postoperatively, the neonate had an uneventful recovery.The urethral catheter was removed on post-operative day 10 after which, he voided spontaneously in a good stream.A repeat ultrasound done after 4 weeks showed complete resolution of the HUN, no diverticulum was visualized.The repeat MCU after 6 months showed normal anatomy.Dimercaptosuccininc acid scan done subsequently showed no scars on either side.

DISCUSSION
Congenital BOO is an association of clinical findings, wherein the normal outflow of urine from the fetal bladder is impaired.The most common causes of congenital BOO are PUV, urethral atresia, and prune belly syndrome.Rarer causes may include prolapse ureterocele, syringocele, hydrocolpos, and congenital bladder diverticula.Antenatally, fetal BOO will most commonly present as urinary tract dilatation and fetal oligohydramnios.The most severe presentation is as neonatal respiratory failure subsequent to pulmonary hypoplasia.Later presentations include an abdominal mass, urinary ascites, UTI, or renal failure.Bladder dysfunction is commonly seen [2].
PCBD are relatively uncommon and occur almost exclusively in males, with only two cases having been reported in females [3].To the best of our knowledge, there have been only three reports of bilateral primary diverticula in the pediatric age group [4][5][6].Most of the patients present in the first decade of life, although presentation has been reported as late as adulthood.The mean age of presentation was 16.8 months in a series of 12 patients reported by Bhat et al. [5].The neonatal presentation as seen in our case is rather unheard of (Table 1).
PCBD are more commonly located in the posterolateral wall of the bladder at the ureteric orifice, which progressively gets incorporated into the diverticulum.As the diverticulum enlarges cranially, it can lead to ureteral obstruction and unilateral hydronephrosis (HDN).Rarely, these may arise posteriorly.The retrovesical location of the diverticulum may produce symptoms of BOO.This diverts more urine to the diverticulum, setting off a vicious cycle [7].
If symptomatic, PCBD usually present as recurrent UTI, hematuria, voiding dysfunction, or bladder stones.Our Antenatal diagnosis is rare, but prenatal scans may show unilateral HDN with diverticula [8].Ultrasound is the preferred initial imaging modality.Diagnosis is challenging, with differentials being bladder ears, hourglass bladder, and vesical hernias.The diverticulum may be visualized along with associated ipsilateral upper tract dilatation [5].About 30% of the times, the diverticulum may be missed on the initial ultrasound, but some degree of HUN is usually present [4].Contrast studies may demonstrate the diverticulum as an outpouching from a full bladder on oblique films (Figure 1).A medial deviation of the ureter is also suggestive [5].Magnetic resonance urography has been proposed as the ideal imaging modality for the diagnosis of PCBD.We, however, had a working diagnosis of PUV, and therefore opted for an MCU, in which the diverticulum was clearly delineated.We consider a well carried out MCU to be the best imaging modality in all patients presenting with BOO.
Management of congenital bladder diverticula varies with presentation.Small, asymptomatic diverticula may be followed conservatively.Surgical excision, however, is indicated in case of recurrent UTI, associated reflux and ureteral or bladder obstruction.Diverticulectomy may be done with or without reimplantation of the ureter.Open, laparoscopic, and vesicoscopic approaches have been described [7][8][9].
Patients, who present before upper tract damage has set in, have better treatment outcomes.A repeat ultra-sound done 4-6 weeks after the surgery usually demonstrates a resolution in the HUN and diverticula.Voiding difficulty following surgery is seen in some patients.It might be secondary to residual anatomic obstruction or functional bladder dysfunction [10].Those patients have persistent post-operative dysfunctional voiding need to undergo a repeat MCU and a urodynamic evaluation [3].