Choroid Plexus Cysts

When Tina and Jim Angelman* of Brighton, Massachusetts saw their baby on the ultrasound screen, it was a moment of pure joy. Exclamations of "Is it a boy or a girl?" and "Look at those tiny hands!" filled the room, until Tina noticed the technician huddling closer to his screen. When he left to get the doctor, Tina filled with dread. The doctor's words fell heavily. "I'm sorry, but I see something that may indicate a problem. Your baby has a choroid plexus cyst."

At that moment, Tina and Jim's feelings about their baby and the pregnancy changed. "It's pretty hard to describe how it feels to go from cloud nine to the worst day of your life in the span of a two-minute conversation. I didn't know what to think—the radiologist didn't really give us a clear picture of what was going on, and it all seemed very vague," says Jim.

A similar scenario played out for Cindy Scoville of Phelps, New York during her 18-week ultrasound. "I was so stressed, worried, sad, and anxious," she said after the doctor revealed that her son had four choroid plexus cysts.

At least one out of one hundred parents will share this frightening experience during a routine ultrasound. What is a choroid plexus cyst? What does it mean? And what can parents do about it?

What is a Choroid Plexus Cyst?

The choroid plexus is an area of the brain that is not involved thinking or personality. Rather, the choroid plexus makes a fluid that protects and nourishes the brain and spinal cord. When a fluid-filled space is seen in the choroid plexus during an ultrasound, it is called a choroid plexus cyst (CPC). "We don't know why, but between 1 and 3 percent of all fetuses will manifest a CPC at 16 to 24 weeks of pregnancy," says Dr. Roy A. Filly, a Professor of Radiology and of Obstetrics, Gynecology and Reproductive Sciences and Chief of the Section of Diagnostic Sonography at University of California, San Francisco. CPCs can be found either on one side of the brain (unilateral) or both sides (bilateral). They can vary in size and shape, from small and round to large and irregular. Some fetuses have more than one.

Regardless of their number, shape or size, choroid plexus cysts are not harmful to the baby. "I am not aware of a single instance where a CPC caused damage to a fetus," says Dr. Filly.

Dr. Peter Doubilet, a Professor of Radiology at Harvard Medical School, agrees, "That's one very important fact. CPCs are not harmful, and they nearly always go away by the third trimester of pregnancy."

If CPCs are found during an ultrasound, the radiologist will scrutinize every organ and body part to look for other abnormalities, such as a malformed heart, head, hands or feet, and stunted growth of the baby. When no other abnormalities are found, the diagnosis is called an "isolated CPC."

The Significance of an Isolated CPC

If CPCs do not cause any damage, why does anyone worry about them? The problem is really one of association—being at the wrong place at the wrong time. Wrong or right, CPCs have become associated with a severe genetic disease called Trisomy 18. It is well documented that about half of babies with Trisomy 18 show a CPC on ultrasound. But Dr. Bronsteen from the Division of Fetal Imaging at William Beaumont Hospital in Royal Oak, Michigan points out, "Nearly all babies with Trisomy 18 who have a CPC have other abnormalities on the ultrasound, especially in the heart, hand, and foot." The real question arises when a baby has a CPC with nothing else wrong: the "isolated CPC."

*Names have been changed by request