Choroid Plexus Cyst on a Pregnancy Scan: Should I Worry?

A choroid plexus cyst is a small fluid-filled space in the choroid plexus, a structure in the baby's brain that makes the fluid around the brain and spinal cord. It is seen in about 1 to 2% of babies and usually disappears by around 28 weeks. When it is the only finding, professional guidance treats it as a normal variant.

The cyst sits in the fluid-making gland, not in the brain matter itself. You may see it written as CPC, and the report may say whether it is on one side or both sides.

This guide explains the finding in general terms. It cannot tell you what the result means for your own pregnancy. Your maternity team reads it alongside your scan, history and screening results.

A choroid plexus cyst does not cause symptoms in you. Other symptoms during pregnancy can still need same-day help, and they should never wait for a routine appointment. The NHS advises calling emergency services straight away if you are pregnant and bleeding with any of the following:

• Heavy bleeding that soaks through a pad soon after you put it on.
• Severe tummy pain that stops you focusing on everyday activities.
• Shoulder pain.
• Feeling sick, faint or dizzy, or losing consciousness.
• Later in pregnancy: if your baby is moving less, has stopped moving, or the usual pattern changes, contact your midwife or maternity unit immediately. Do not wait until the next day, and do not rely on a home heartbeat monitor.
• A severe headache that does not ease with simple painkillers, vision problems such as blurring or flashing lights, pain below the ribs, or sudden swelling of the face, hands or feet. These can be signs of pre-eclampsia and need checking immediately through your maternity unit.

Usually, yes. The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) says most choroid plexus cysts have gone by the 28th week of pregnancy.

For babies whose chromosomes are typical, ISUOG reports that studies have not shown differences in brain function, movement or behaviour, so no check after birth is needed for the cyst. The Society for Maternal-Fetal Medicine (SMFM) also says that, after a low-chance screening result, an isolated cyst needs no follow-up scan and no evaluation after birth.

Choroid plexus cysts have been reported in some babies with trisomy 18 (Edwards' syndrome). ISUOG notes that about one third of babies with trisomy 18 have these cysts. That does not work the other way round: most babies with a cyst do not have a chromosomal condition, and in reported series, chromosomal differences were mostly found when other anomalies were also seen on the scan.

SMFM, in guidance supported by ACOG, says that after a negative (low-chance) blood or cell-free DNA screening result, an isolated choroid plexus cyst is a normal variant of no clinical importance and needs no further evaluation for chromosomal conditions.

If no screening was done earlier, SMFM recommends counselling about the chance of trisomy 18 and offering screening, such as a cell-free DNA test or a quad blood test. Screening tests look at chance and do not diagnose. Whether to have any test is your choice.

'Isolated' means the cyst is the only notable finding after a detailed scan. SMFM defines it as a soft marker seen with no structural anomaly, no growth restriction and no other soft marker. ISUOG says an isolated cyst does not change how the pregnancy is managed.

If other findings are seen, the team considers everything together. ISUOG notes that in this situation, further tests such as cell-free DNA screening or amniocentesis may be offered, depending on what is available and what you choose. Ask your team which situation your report describes.

Often not. In England, the NHS Fetal Anomaly Screening Programme lists choroid plexus cysts as a normal variant. If one is seen at the 20-week scan, no referral for further assessment is needed as part of the screening programme.

SMFM advises against diagnostic testing, such as amniocentesis, solely because of an isolated soft marker after a negative screening result. Local practice can differ, so ask your own team what they recommend and why.

Writing these down before your appointment can help you leave with clear answers. Leave space beside each one for the reply.

• Is the choroid plexus cyst the only finding, or were other findings seen on the detailed scan?
• Is there one cyst or more, and on one side or both?
• How does this fit with my earlier screening result, if I had one?
• If I have not had screening, what options do I have now, and what would each one tell me?
• Is a follow-up scan planned, and if so, what is it looking for?
• Does this change anything about my care for the rest of the pregnancy or after birth?
• Who should I contact if I have more questions after today?

On SameCase, patients and verified doctors share de-identified cases. Reading how others with a choroid plexus cyst on their scan discussed it with their care team can help you spot questions you had not thought of, such as whether a later scan was planned and why.

Other people's cases cannot tell you what your scan means or predict how your pregnancy will go. Use them to prepare questions, then take those questions to your own maternity team.

Hearing the word 'cyst' in relation to your baby's brain can be frightening, even when the team says it is common and usually goes away. It is reasonable to ask for the finding to be explained again in plain words, or for a written summary of what was seen.

If worry persists, tell your midwife. They can go through the results with you and point you to support services in your area.