What is a cystic hygroma?
A cystic hygromas is a cyst, or a group of cysts, found mostly in the neck. Cystic hygromas are caused by an error in the development of lymph sacs and lymph vessels as the baby is developing during pregnancy.
By the end of the fifth week of pregnancy, the baby's lymphatic tissues form as lymph sacs develop from veins. The first lymph sacs to appear serve the chest, arms, neck, and head. These lymph sacs sprout a network of channels called lymphatic vessels that maintain fluid in the baby's body, and carry fats and immune system cells. When a problem occurs between the veins and developing lymph sacs, the sacs expand with fluid and partially or completely block this system of vessels. These blockages cause many health problems.
How is a cystic hygroma detected?
A cystic hygroma can be found on a routine ultrasound during pregnancy. At about 10 weeks of pregnancy, ultrasounds show some babies to have more fluid at the back of the neck. This fluid appears as a large, clear space, referred to as "increased nuchal fold," "nuchal thickness," or "nuchal lucency." A blood test done at 15 to 20 weeks of pregnancy can also help detect cystic hygroma. The test measures Alpha-fetoprotein (AFP), a substance made by your baby and present in your bloodstream. Mothers of babies with cystic hygroma have a high Alpha Fetal Protein (AFP) level in about half of cases.
How does a cystic hygroma affect my baby's health?
Small cystic hygromas are more likely to disappear by themselves, causing no further problems for your baby. A majority of cystic hygromas grow to be very large. In fact, 85 percent, become larger than the fetal head.
Some cystic hygromas cause additional conditions such as:
- extra folds of skin on the neck ("webbed neck")
- tissue swelling
- "lymphangiomas," non-cancerous tumors on the skin
- "hydrops," the formation of extra fluid within the baby's body, which can lead to miscarriage or fetal death
Both the size of the cystic hygroma and the presence of other abnormalities affect your baby's overall condition. Your doctor will recommend an amniocentesis, a test to detect abnormal chromosomes. Your doctor will also schedule several ultrasounds to follow your baby's condition.
A cystic hygroma can affect the amount of fluid surrounding your baby as well as within the baby. When there is not enough or too much amniotic fluid, your baby has less of a chance for a healthy outcome. Too much fluid within the baby's body ("hydrops") occurs in 25 to 75 percent of cases. Hydrops is a very serious condition which often leads to miscarriage or fetal death. A baby with no other health problem and a small cystic hygroma will be observed by ultrasound every three to four weeks.
If my baby's chromosomes are normal
If your baby has normal chromosomes and the cystic hygroma disappears by 20 weeks of pregnancy, the outcome will probably be good. If the cystic hygroma does not resolve by 20 weeks, the chance of a healthy outcome decreases to two to nine percent.
If my baby has a chromosomal abnormality
About 60 percent of cystic hygromas result from chromosomal abnormalities. In these cases the baby often has a set of abnormalities known as a "genetic syndrome." Some genetic syndromes seen with cystic hygroma are Turners, Noonan, Penashokeir and Roberts syndromes, and Trisomies 13, 18, and 21 (Down Syndrome.)
A cystic hygroma can also occur from an unknown cause. Some environmental causes such as maternal viral infections and excessive maternal alcohol use are known to cause cystic hygroma.
How will a cystic hygroma affect my baby's birth?
Babies with cystic hygroma should be delivered at a tertiary center, a hospital with the staff and equipment ready to support a baby needing specialized care. Your doctor will discuss with you whether a vaginal delivery or Caesarean section is best for you and your baby. If the cystic hygroma is large, Caesarean section may be necessary.
What will happen after birth?
A neonatologist will closely observe your baby to make sure he or she is breathing normally.
Will my baby need surgery later?
If the cystic hygroma interferes with breathing, there are two options:
- Surgery: A pediatric surgeon will be consulted if the neonatologist recommends surgery. Surgery involves some overnight hospital stay and may result in a scar. There is a 10 to 15 percent chance a cystic hygroma may recur after surgery.
- Sclerotherapy: This is an outpatient, non-surgical procedure to limit the effects of cystic hygroma A radiologist uses ultrasound to help guide a thin needle into the cyst. Medicine is injected through the needle into the cyst, causing the lymphatic vessels to shrink. The procedure takes about 30 minutes, does not require an incision, and involves very little risk of bleeding or infection. The anesthesiologist places your baby in a deep sleep with general anesthesia. This is considered very safe.
© 2016 Monroe Carell Jr. Children's Hospital at Vanderbilt