Posterior Urethral Valves (PUV)

What are posterior urethral valves?

Posterior urethral valves (or PUV) are an abnormality of the urethra, which is the tube that drains urine from the bladder to the outside of the body for elimination. The abnormality occurs when the urethral valves, which are small leaflets of tissue, have a narrow, slit-like opening that partially impedes urine outflow. Reverse flow occurs and can affect all of the urinary tract organs including the urethra, bladder, ureters, and kidneys. The organs of the urinary tract become engorged with urine and swell, causing tissue and cell damage. The degree of urinary outflow obstruction will determine the severity of the urinary tract problems.

What causes posterior urethral valves?

PUV are the most common cause of severe types of urinary tract obstruction in children. It is thought to develop in the early stages of fetal development. The abnormality affects only males and occurs in about one in 8,000 births. This disorder is usually sporadic (occurs by chance). However, some cases have been seen in twins and siblings, suggesting a genetic component.

What are the symptoms of posterior urethral valves?

The syndrome may occur in varying degrees from mild to severe. The following are the most common symptoms of posterior urethral valves. However, each child may experience symptoms differently. Symptoms may include:

• An enlarged bladder that may be detectable through the abdomen as a large mass

• Urinary tract infection, or UTI (usually uncommon in children younger than age 5 and unlikely in boys at any age, unless an obstruction is present)

• Painful urination

• Weak urine stream

• Urinary frequency

• Bedwetting or wetting pants after the child has been toilet trained

• Poor weight gain

• Difficulty with urination

The symptoms of PUV may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.

How are posterior urethral valves diagnosed?

The severity of the obstruction often determines how a diagnosis is made. Often, PUV are diagnosed by fetal ultrasound while a woman is still pregnant. Children who are diagnosed later often have developed urinary tract infections that require evaluation by a physician. This may prompt your physician to perform further diagnostic tests, which may include:

• Abdominal ultrasound. A diagnostic imaging technique that uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.

• Voiding cystourethrogram (VCUG). A specific X-ray that examines the urinary tract. A catheter (hollow tube) is placed in the urethra (tube that drains urine from the bladder to the outside of the body) and the bladder is filled with a liquid dye. X-ray images will be taken as the bladder fills and empties. The images will show if there is any reverse flow of urine into the ureters and kidneys.

• Endoscopy. A test that uses a small, flexible tube with a light and a camera lens at the end (endoscope) to examine the inside of part of the urinary tract. Tissue samples from inside the urinary tract may also be taken for examination and testing.

• Blood test. A blood test may be ordered to assess your child's electrolytes and to determine kidney function.

What is the treatment for posterior urethral valves?

Specific treatment for PUV will be determined by your child's physician based on:

• Your child's age, overall health, and medical history

• The extent of the abnormality

• Your child's tolerance for specific medications, procedures, or therapies

• Expectations for the course of the abnormality

• Your opinion or preference

Treatment for PUV depends on the severity of the condition. Treatment may include the following:

• Supportive care. Initially, treatment may focus on relieving your child's symptoms. If your child has a urinary tract infection, is dehydrated, and/or has electrolyte irregularities, these conditions will be treated first. Your child may have a catheter placed in his bladder (a small hollow tube that is inserted into the penis through the urethra and is threaded up into the bladder). Your child may also receive antibiotic therapy and intravenous (IV) fluids.

• Endoscopic ablation. After the initial management, a urologist (a physician who specializes in the disorders and care of the urinary tract and the male genital tract) may see your child. The urologist may perform a procedure called an endoscopic ablation. During this procedure, the urologist will insert an endoscope, a small, flexible tube with a light and a camera lens at the end. With this tube he or she will examine the obstruction and remove the valve leaflets through a small incision.

• Vesicostomy. In certain situations, a different procedure called a vesicostomy may be required. A vesicostomy is a small opening made in the bladder through the abdomen. Usually this opening is repaired at a later time when the valves can be cut more safely.

Nearly 30 percent of boys with PUV may have some long-term kidney failure that may need to be addressed. The prognosis for PUV improves when detected early.