Posterior urethral valves masquerading as neuropathic bladder following sacrococcygeal teratoma resection

Abstract

Neuropathic bladder may be a co-associated morbidity in newborn babies following resection of a sacrococcygeal teratoma. We report a case of a male newborn showing features of incomplete urinary voiding requiring intermittent catheterisation after operation for bladder emptying. Videourodynamic assessment excluded neuropathic bladder and posterior urethral valves were demonstrated on micturating cystography. Urology outcomes have been excellent following curative valve ablation. This report highlights the crucial importance of being aware of the rare coexistence of lower urinary tract pathology in male babies with sacrococcygeal teratoma. Routine urodynamic assessment should be considered in all children following sacrococcygeal teratoma resection.

Background

Sacrococcygeal teratoma is the most common congenital neoplasm in newborn babies. Four times more common in girls, sacrococcygeal teratoma has an incidence of 1:40000.¹ It may be an isolated neoplastic lesion, but there are well-recognised associations with sacral agenesis and varied anorectal malformations, most notably the Currarino triad. To the best of our knowledge, sacrococcygeal teratomas do not usually have an association with posterior urethral valves in males. Functional outcome studies indicate that, following resection of a sacrococcygeal teratoma, some 20–30% of patients may suffer neuropathic bladder and bowel problems.² It is not fully known whether these sequelae are linked directly with tumour development in utero damaging pelvic and sacral nerve plexuses or whether they follow tumour resection.

Case history

A mother was induced electively at 38 weeks of gestation due to antenatal diagnosis of sacrococcygeal teratoma in the fetus. Magnetic resonance imaging after birth confirmed an Altman stage III sacrococcygeal teratoma (Figure 1). Right-sided pelvicalyceal urinary tract dilatation was evident on screening. Alphafetoprotein level at birth was 650,000iu/ml and serum creatinine on day two of life was 59μmol/ml (range 29–94μmol/ml). On day four of life the infant underwent tumour resection with coccygectomy using a posterior sagittal anorectoplasty approach.

Figure 1 .

A preoperative sagittal T2 weighted magnetic resonance image demonstrating a large abdominopelvic Altman stage III sacrococcygeal teratoma

Pathology showed a wholly benign teratoma with no malignant elements On day three postoperatively, the urinary catheter was removed and the baby voided small volumes of urine. Ultrasound scans showed residual bladder urine volumes of 70–100ml with fullness of the upper tract collecting systems. The infant was suspected to have neuropathic bladder after tumour resection and a programme of clean intermittent catheterisation was commenced. Videourodynamics were then scheduled with aftercare follow-up.

Urodynamics demonstrated a compliant bladder with no vesicoureteral reflux. The patient voided incompletely after 50ml of filling, but it was noted that the male patient had a dilated posterior urethra (Figure 2). Cystourethroscopy confirmed posterior urethral valves, which were ablated and circumcision then undertaken to offset the risk of recurrent urinary tract infection. At 15-month follow-up, full bladder emptying was maintained and urinary tract studies were satisfactory with no episodes of infection. The patient was tumour free at 18 months and is thriving.

Figure 2 .

Voiding cystogram study showing a dilated posterior urethra confirming posterior urethral valves

Discussion

Urodynamic assessment remains the gold standard for diagnosis of a neuropathic bladder and can pick up abnormalities in patients with no clinical or radiological evidence of bladder dysfunction.³ Some groups, therefore, advocate routine urodynamics following sacrococcygeal teratoma resection.³ If urodynamic assessment is done with radiological screening (known as videourodynamics) then additional anatomical information about the urinary tract is acquired. Videourodynamics are routine in our centre and, in this boy, led to the diagnosis of posterior urethral valves. The diagnosis otherwise may have remained undetected for some time, although the difficulty in catheterising provided an additional clue. Thankfully, the upper tract changes were minimal and temporary: long-term renal function is likely to be normal.

Posterior urethral valves are the most common cause of renal failure secondary to obstructive uropathy in males. Many cases are suspected prenatally, with prenatal ultrasound features including bilateral hydroureteronephrosis and oligohydramnios.⁴ A second cohort exists of boys postnatally diagnosed. In these patients, renal pelvic dilatation may be minimal or even absent.⁵ Postnatal micturating cystourethrogram demonstrates a widened posterior urethra and poor voiding. Valve ablation is ‘curative’ in alleviating obstructive voiding.

This interesting and very rare case highlights the need for thorough urinary tract evaluation in male infants showing voiding urinary symptoms after sacrococcygeal teratoma resection. It is our routine practice at Alder Hey Children’s Hospital, Liverpool, that all patients with sacrococcygeal teratoma are carefully followed-up at clinic visits by a multidisciplinary team including paediatric oncology surgeons, colorectal specialist and urologists to monitor for postoperative functional sequelae. In this case, timely intervention lead to curative valve ablation after resection, preserving normal renal tract function and bladder voiding. Routine urodynamic assessment should be considered in all children, including asymptomatic, following sacrococcygeal teratoma resection.