Posterior urethral valves

Definition: congenital malformation in males where membranous folds of the urogenital membrane obstruct the membranous and prostatic urethra (posterior urethra) (aka incomplete canalization)
Clinical features
- Most common cause of urinary tract obstruction in newborn males
- Respiratory distress secondary to pulmonary hypoplasia in cases with severe obstruction (see “Potter sequence”)
- Abdominal distention due to bladder distention
- Late manifestations:
  - Difficulty voiding, poor urinary stream
  - UTIs → urosepsis
  - Diurnal enuresis
  - Failure to thrive
Diagnostics
- Voiding cystourethrogram (diagnostic study of choice) demonstrates
  - Dilation/elongation of the posterior urethra during voiding
  - Signs of vesicoureteral reflux (if present)
- Prenatal ultrasound of the upper urinary tract may demonstrate:
  - Distended and/or thick-walled bladder, due to increased force to overcome pressure
  - Bilateral hydroureters
  - Bilateral hydronephrosis