What are posterior urethral valves or PUV for short?
Posterior urethral valves occur only in boys. It is due to a blockage in the urethra or the tube leading from the bladder to the outside (see diagram). Urine is made by the filtering units (nephrons) in the kidney which filter waste products from the blood and excrete excess water. The urine that is formed flows down the ureter and is stored in the bladder before being passed out in the urethra which passes through the penis. A blockage to the urine flow through the urethra causes back pressure on the bladder which may enlarge considerably and/or develop a very thick muscle wall. This in turn can lead to further back pressure up the ureters and lead to excess fluid in the kidneys called hydronephrosis. Each child who presents with PUV has a different amount of damage to the urinary system (bladder, ureters and kidneys) – some may have a mild problem whereas in others PUV may have caused severe damage in the womb.
