Children's Hospital Colorado
Colorado Fetal Care Center

Cystic Hygroma

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What is cystic hygroma (lymphatic malformation)?

Cystic hygroma is a condition caused by a problem in the lymphatic system that can be seen at any point in pregnancy but most commonly in the first trimester. It is also called lymphatic malformation, lymphangioma or venolymphatic malformation. Fetuses with this condition have atypical skin thickening, usually at the back of the neck. In more severe cases, thickening can occur along the entire length of the body.

These unborn babies also have thin membranes (called septations) that extend from the skin into the underlying tissue, forming cysts under the skin. These changes may be visible during an abdominal or vaginal ultrasound you have during early pregnancy. They are also visible on ultrasound around 18 to 20 weeks of pregnancy.

What are the complications of cystic hygroma?

The concern with cystic hygroma in early pregnancy is not the cystic hygroma itself, but other problems that may come with it.

Up to 50% of fetuses with cystic hygroma in early pregnancy also have an abnormal number of chromosomes. Chromosomes are the genetic blueprint of the developing fetus. When a baby has too many, too few or duplicate chromosomes, they develop disorders such as Down syndrome, Trisomy 13 or 18 or Turner syndrome. Chromosomal abnormalities often result in miscarriage during the first trimester.

A diagnosis of cystic hygroma also increases the risk of other conditions. The fetus’s heart, skeleton or other organs may not develop properly. In the most severe cases, the fetus may develop fetal hydrops — a dangerous accumulation of fluid around the heart, lungs or in the skin.

How common is cystic hygroma?

Cystic hygroma is most commonly seen in early pregnancy. This condition is frequently diagnosed in the first trimester and affects about 1 in every 285 pregnancies.

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