Marie, I have been worried for three days, as during my 21-week ultrasound, the technician told me he saw two cysts in my baby’s brain. My partner and I were shocked, but all he said was “talk to your doctor about the next steps, and don’t worry.” How can I not worry?! Can you tell me about these cysts? Thanks in advance, Annie

Dear Annie,

You are not the only parents to worry about this kind of discover. I understand your concern, as parents are always hoping to get healthy, typical results during an ultrasound. Thanks to technology and new generations of ultrasound detection devices, we can see things we couldn’t even a few short years ago.

That said, an isolated choroid plexus cyst is a type of pocket (cyst) or rounded fold filled with a clear liquid in the different neurological and epithelial (cell) structures that look like a sponge on the screen. It’s part of the brain’s anatomical fetal development as the pregnancy progresses. According to experts, it is a physiological process that does not involve abnormal components.

Annie, this is often isolated and is found in the fetus before 24 weeks of pregnancy. The fetus is perfectly normal, the cyst is not dangerous, and is not associated with a specific problem. This is even truer if your nuchal translucency and blood markers (results of your blood tests) came back fine at the end of your first trimester.

According to statistics on the topic, 0.6-3% of the general population can have a choroid cyst. The cyst will usually disappear on its own as the fetus develops. It is replaced by conjunctive tissues around 27-28 weeks during the third trimester.

Additional examinations will be required at the chromosomal level (fetal karyotype amniocentesis) of the fetus only if the cyst is abnormally large, bilateral and found in the control ultrasound after 28 weeks of pregnancy. This is also the case if associated already identified malformations (other anomalies) were noted in the fetus.

Annie, I hope this short answer can help you better understand your situation and help guide you when talking with your doctor.

Talk soon,


The Baby Expert