Posterior urethral valves are a relatively frequent malformation which occur nearly exclusively in boys. The manifestation of severe types of valves already takes place pre- or postnatally in the newborn or young infant; slight types are recognized later, sometimes even in schoolchildren.

1. One of the most frequent causes of obstructive uropathy of the lower urinary tract and of voiding dysfunction in newborns and infants.
2. Depending on the grade of obstruction, there are different clinical presentations.
3. Possible cause of a chronic disease and of death: Renal insufficiency, sequels to the upper urinary tract, and disturbances of bladder function.

Unknown.

Instead of a crista urethralis there is a structure similar to a swallow's nest, e.g. an accentuation of the normal folds that emanate from the distal end of the verumontanum, impairing urinary flow (= Type I of Young). Less frequently, a membrane with a central hole is observed (= Type III of Young) which is located distally of the colliculus seminalis.

Severe types of valves lead to secondary changes of the bladder, such as hypertrophy of the bladder muscles and bladder diverticula; the so-called valve bladder causes obstructive megaureters and secondary vesicoureteral reflux.
To the primary nephropathy (dysplasia) a secondary damage may be added by reflux and obstruction of the ureters. The involvement of the bladder wall leads to functional disturbances even if the obstruction is removed by endoscopical ablation of the valves.

Prenatal findings: Bilateral hydronephrosis combined with visible dilated ureters and a constantly filled, thick-walled bladder on ultrasound; in addition, oligohydramnion, lung hypoplasia, and a pathological content of the urine and the amniotic fluid may be found.

History and findings in newborns: Urinary retention, dripping and/or a weak urinary stream. Chronic retention of urine with a visible and palpable tumor (bladder) in the lower mid-abdomen, clinical signs of renal insufficiency and of respiratory distress syndrome.

History and findings in infants, toddlers, and schoolchildren: Besides voiding disorders, there are complicated urinary tract infections and urosepsis, slight disorders of voiding as impeded micturation (use of the abdominal wall muscles, delayed start of micturation), weak urine stream, enuresis.

Failure to treat severe cases leads to death due to renal insufficiency and septicaemia, while slight types of valves will have a continual voiding disorder with possible damage to the bladder wall.

The differential diagnosis includes all lesions which lead to voiding disorders and/or to urinary tract infection; and prenatally and/or in the newborn to renal insufficiency, respiratory distress syndrome, urinary retention, and an abdominal tumor (full bladder, urinary ascites and/or hydronephrosis as cause).

- For confirming the clinical diagnosis of urethral valves: VCUG (=voiding cystourethrography) and cystoscopy;
- for the evaluation of the upper and lower urinary tract: ultrasound, IVU, VCUG and MRI;
- for the evaluation of the kindneys: blood (azotemia, acidosis, septicemia) and urine analysis, renal scanning etc.;
- for the evaluation of the bladder: ultrasound, VCUG, uroflowmetry, urodynamic studies.

The prenatal insertion of a vesicoamniotic shunt is controversially discussed.
Postnatally: immediate intravenous resuscitation with correction of possible electrolyte imbalance and acidosis. Catheter drainage of the bladder, and, as soon as possible, endoscopical valve ablation or drainage by vesicostomy as a temporary measure.
Treatment of possible renal insufficiency, of secondary lesions of the upper urinary tract, and of the functional bladder disorder.

1/3 of the children die of renal failure (included the prenatally recognized patients), 1/3 survive with different degrees of disorders of renal and bladder function, and 1/3 are without any sequels.
In contrast to the possible renal and bladder dysfunction (some of the patients need a dialysis and later a renal transplantation, and a non-operative treatment of the bladder dysfunction), there may be a good morphological recovery of the upper and lower urinary tract with appropriate follow-ups.