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This is a transcription of a portion of a Healthful Woman podcast.

Anastasia’s Question

Hey, everyone. Welcome to Mailbag 25: What Does the Fox Say? Our first question is from Anastasia, and it’s on choroid plexus cysts. “Hi. My 20-week anatomy scan showed that my baby has bilateral choroid plexus cysts. His genetic tests in the first trimester were all negative, and the rest of the anatomy scan was normal. My nurse practitioner explained that although he has these little cysts, since there were no other ‘soft indicators,’ the cysts are likely to resolve by the time he is born. She was very thorough in talking to me about it and put it in order for a third-trimester scan. She also warned me not to Google it when I get home. Well, I Googled it. And now, I’m freaking out. What if the cysts are still there at the third scan? What if he’s born with them? Have there been any findings in babies who had cysts that have now resolved and could have impacted them? Could the genetic test have missed something? Is he in fact at risk? Thank you, Dr. Fox.”

Dr. Fox’s Response

All right, Anastasia, good question. The short answer is no, don’t worry. Okay. Here’s the long answer. So, basically, choroid plexus cysts are little cysts, which are fluid-filled pockets that we see in the structure of the choroid plexus. So, the choroid plexus is in the baby’s or the fetus’s brain. It’s supposed to be there. The choroid plexus makes spinal fluid and secretes it into the system of channels and tunnels and whatnot in the baby’s brain. And so, that’s all supposed to be there. That’s all normal. Sometimes, when we look at this choroid plexus, it looks like a spongy material. And every now and then, within it, we see little pockets of fluid, and those are cysts.

In terms of the cysts themselves, they’re not dangerous to the baby. They’re not a brain problem. They don’t hurt the brain. They don’t affect development. Nothing like that. So, actually, in fact, while it’s fine to get a follow-up scan in the third trimester, you don’t even really need to because they don’t need to be followed up because whether they stay or whether they go away is not relevant to the health of the baby. It’s not something that needs to be followed up after birth. Right. They’re totally fine to have.

The concern with choroid plexus cysts is really an older one. Back in the day, when there was really no or very minimal genetic screening, seeing choroid plexus cysts increased the risk slightly of the baby having something called trisomy 18, which is a very, very severe genetic condition. Now, most babies who have choroid plexus cysts…not just most. The vast majority of babies who have choroid plexus cysts do not have trisomy 18. They’re perfectly fine. But sort of when there was a time when there was no genetic screening, there was no nuchal, there was no NIPT, and people just sort of showed up for 20-week ultrasound, if you saw choroid plexus cysts, we’d have to decide, all right, do I need to do, like, an amniocentesis to check for trisomy 18, or do I not need to do it?

Even back then, if the baby otherwise looked normal, the chance of trisomy 18 was exceedingly low, and we usually didn’t worry too much about it, but it was a conversation. But nowadays, when there’s genetic screening, and people have all this sort of pre-screening before their 20-week ultrasound, if the baby looks fine and we see these choroid plexus cysts, basically, we ignore them. Meaning, the chance that the baby would have trisomy 18 is so minimal that we don’t even, like, drop that. So, when you Google it, it can be very terrifying because sometimes you’ll find a website that will say, oh, it’s linked with trisomy 18. And while that’s not false, it’s really out of context. And so, nowadays, it’s not really the same thing.

So, if I see someone who at 20 weeks, just like you, everything’s been normal, screening’s been normal, baby looks fine, and I see these choroid plexus cysts, it’s actually a debate of whether we should even tell people about it because, since it has no consequence whatsoever, by telling people, you may just be scaring them unnecessarily. So, different people fall on that line differently. Some talk about it, some don’t talk about it, but either way, it’s not anything to be concerned about. All is well. Not a problem.

Maternal Fetal Medicine blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!