What is the most common congenital urethral obstruction in male infants?

The most common congenital urethral obstruction in male infants is posterior urethral valves. These valves are abnormal folds of tissue that form in the posterior urethra and create an obstruction, leading to varying degrees of urinary retention. This condition is especially important because it can result in serious complications if not identified and managed promptly, such as bladder damage and kidney dysfunction.

In male infants, this condition is particularly notable as it can manifest early in life, often detected through prenatal ultrasound indicating hydronephrosis or oligohydramnios. The presence of posterior urethral valves typically requires surgical intervention to relieve the obstruction and prevent further complications.

Other conditions listed do not primarily involve urethral obstruction. For instance, hypospadias refers to a congenital anomaly where the urethral opening is on the underside of the penis, urethral stricture typically occurs due to scarring or injury and is not congenital, while prune belly syndrome involves the absence of abdominal muscles and is associated with urinary tract abnormalities but is not solely a urethral obstruction. Thus, posterior urethral valves stand out as the most common and significant congenital cause of urethral obstruction in male infants.