Source: Indys Child Parenting Magazine

A Common Sight on Ultrasounds
Kidney swelling detected during pregnancy usually resolves on its own

by Dr. Mark Cain

April 01, 2011

For most parents, ultrasounds during pregnancy bring a mixture of excitement and anxiety. No one wants to hear that anything looks out of the ordinary. But in 1 to 2 percent of pregnancies, an ultrasound detects a fluid-filled enlargement of the kidney known as prenatal hydronephrosis. In fact, its the most common abnormality found through ultrasounds.

This condition can be serious and must be monitored closely. But the good news is that in most cases, the problem either resolves spontaneously or can be corrected.

What is prenatal hydronephrosis?

The kidneys are two bean-shaped organs that filter waste products from the blood and produce urine. They develop early in pregnancy and are among the first organs to appear on maternal ultrasounds, becoming visible by the 14th or 15th week of gestation. Prenatal hydronephrosis is a swelling of the kidney due to a backup of urine.

In about 80 percent of cases, prenatal hydronephrosis is caused by a partial obstruction or blockage of the ureter, the tube that transports urine from the kidney to the bladder. The next most common cause is reflux, in which urine from the bladder moves backwards into the kidney.

Next steps

Dont panic if your doctor detects prenatal hydronephrosis before your child is born. Most of the time, the condition will correct itself. The key is identifying the small number of patients who will need specialized medical help after birth.

When follow-up ultrasounds indicate that treatment may be required, the next step is a referral to a pediatric urologist.

Treatment options

The first visit to a pediatric urologist should occur between the 20th and 30th week of pregnancy. This provides time for the physician to monitor the situation, get to know your family and develop a plan for after your baby is born. There is still a good chance that the hydronephrosis will go away without treatment before or in the first few months after birth. But if kidney function is found to be impaired, the kidney is significantly enlarged, or structural abnormalities are suspected, a treatment plan might include:

Oral antibiotic therapy, starting on the day of birth and continuing until the cause of the underlying problem is determined. This prevents urinary tract infections.

Ultrasounds of the baby to examine the kidneys more closely.

A specialized X-ray in cases where reflux is suspected.

Surgery for a small subset of patients. In most cases, surgery is successful and resolves the underlying issues.

For the last two years, the Pediatric Urology division of Riley Hospital for Children at Indiana University Health has been recognized with a top-three ranking by U.S. News & World Report.

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