Ultrasonic diagnosis of posterior urethral valve in neonates.

The availability of real time ultrasound units with small transducer heads has made perineal ultrasonography a practical proposition in infants. The findings of a dilated posterior urethra and bladder obstruction in a male infant indicate the high probability of a posterior urethral valve. The features seen in the urethra as well as those in the bladder and kidneys are demonstrated.