• 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