Posterior urethral valves: small pieces of tissue in the male urethra that prevent the normal flow or urine out of the body. Posterior urethral valves are the most common cause of urinary outflow obstruction in male children and occur once in about 8,000 births. Symptoms depend upon the degree of obstruction. In most cases the diagnosis can be made before birth, when swelling and enlargement of the urinary tract are seen on ultrasound. Milder cases may not become apparent until later in life. Symptoms can include urinary tract infection, enlarged bladder, weak urine stream, difficulty or pain with urination, bedwetting after toilet training has occurred, poor weight gain, and urinating frequently. Treatment involves surgically removing the obstructing tissue using a specialized endoscopic instrument that is inserted into the urethra.
REFERENCE: Longo, D.L., et al. Harrison's Principles of Internal Medicine, 18th ed. United States: McGraw-Hill Professional, 2012.