Pyelectasis

Pyelectasis, or urinary tract dilation A1, is an increased collection of urine in the part of the baby’s kidney called the renal pelvis. Approximately 1 in every 40 pregnancies has pyelectasis, and this can be seen in one or both kidneys. Pyelectasis can occur in any pregnancy but is more common in boys.

Can pyelectasis cause problems for the pregnancy?

In 90% of pregnancies, pyelectasis resolves during the pregnancy or after delivery without any treatment. You will likely have additional ultrasounds as the pregnancy continues to determine if the amount of urine has decreased, remained the same, or increased. If the amount of urine increases, the baby may need additional monitoring, such as ultrasounds of the kidneys, after delivery. You may also be referred to a kidney specialist, called a nephrologist, to help make recommendations for follow-up care during your pregnancy as well as follow-up care for your baby once he or she is born. Surgery is rarely needed.

Could pyelectasis mean the baby has other health concerns?

If pyelectasis is the only finding on ultrasound, it is typically thought to be normal variation in the baby’s development. Rarely, a baby with pyelectasis may have a chromosome condition, such as Down syndrome. Down syndrome is a genetic condition that causes intellectual disabilities and an increased risk for health problems. In babies where a chromosome condition is suspected, there are usually other ultrasound findings or abnormal blood tests present.

Do I need to consider additional testing?

In most pregnancies, this finding does not significantly increase the chances of a chromosome condition. If you have already had normal blood testing (such as noninvasive prenatal testing, first trimester screening, or quad screening) and pyelectasis is the only finding on ultrasound, the chance for a chromosome condition is still well under 1% and additional testing is not indicated. If you have not had any testing for chromosome conditions in the pregnancy, there are tests available to provide additional information about these risks now that pyelectasis has been identified on ultrasound.

Where can I get more information?

You can speak with your obstetrician or a genetic counselor if you have additional questions about this ultrasound finding. To schedule a genetic counseling appointment, please call 713-486-9302.