Posterior Urethral Valve (PUV)

posterior urethral valve

The urethra is the last part of the urinary tract that drains urine from the bladder to the outside of the body.  PUV is a condition thought to develop in the early stage of fetal development, with abnormal structure that consists of some folds or leaflets of tissue that blocks the bladder outlet. This causes urine build-up and subsequently increases the pressure inside the bladder, causing irreversible damage to the bladder and kidneys. PUV only affects male infants.  It is the most common cause of end stage renal disease due to urinary tract obstruction in children. 

Diagnosis

Often PUV is first caught by fetal ultrasound. On ultrasound, a large amount of urine gets accumulated in the kidneys, as well as an abnormal bladder. Children with PUV who are not diagnosed in womb could present years later due to difficulty voiding, recurrent urinary tract infection, or incidental finding of abnormal kidney ultrasound without any symptoms. PUV often is related to a condition called Prune-Belly syndrome, a constellation of symptoms with defect in abdominal muscle, constipation, failure of both testes to descend into their normal location, and rarely, underdeveloped lungs.

Treatment

PUV is confirmed on a study called VCUG (link). Once confirmed, it requires immediate surgical intervention by a urologist who will remove the abnormal valve as early as possible within the first week of life. Before the procedure, a foley catheter insertion is required to temporally keep the bladder outlet open to drain urine out.

As PUV develops in the very early stage of fetal life, the damage to the kidneys and bladder due to blockage of urine is usually severe, although we do see some milder cases occasionally.  Multiple surgeries might be indicated at different stages. Often, children will need surgery to create an opening in the lower belly through the abdominal wall into the bladder using different techniques. This allows an easy access by a catheter to drain and empty the bladder. Children with PUV require long-term follow up with both urology and nephrology. They eventually will need some medications to manage issues related to advanced chronic kidney disease.  It may take a few months to more than a decade before a child eventually advanced to ESRD.

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