- A soft marker is a finding that slightly raises statistical risk — it is not a diagnosis.
- In isolation, most soft markers carry very little weight, especially with reassuring first-trimester screening.
- The two most common — choroid plexus cyst and echogenic intracardiac focus — are essentially normal variants in most cases.
- Echogenic bowel is the soft marker that warrants the most follow-up. The others are usually monitored or noted.
- Multiple soft markers in combination are more meaningful than any single one.
The hardest moment in our pregnancy was reading the words “bilateral choroid plexus cysts noted” on the post-scan report. We had been told the scan went well. The sonographer was warm, professional, finished on time. Then the report arrived three days later and that line was sitting in the middle of paragraph four, in the same calm font as “normal fetal biometry.”
That's the soft marker problem. The wording on the report doesn't match the clinical weight of the finding. “Cysts in the brain” sounds like the worst possible thing. The actual clinical significance, in most cases, is somewhere between “completely unremarkable” and “mention at the next appointment.” But you don't know that unless someone tells you. So I'm telling you now.
This is a walkthrough of every major soft marker you might see on a 20-week anatomy scan report. What it is, why it appears, how common it is, and what it actually means in clinical practice. If you haven't read it yet, the complete dad's guide to the 20-week scan is the broader companion to this article.
What “soft marker” actually means
A soft marker is a sonographic finding that is not a structural defect, but that has been associated — statistically, in large population studies — with a slightly elevated rate of chromosomal conditions. The classic chromosomal conditions of concern are Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome), and Trisomy 13 (Patau syndrome).
The word “slightly” is doing enormous work in that definition. For most soft markers, the increase in risk is small enough that, in a low-risk pregnancy with reassuring first-trimester screening (NIPT or combined screening), the post-test probability is still very low. The marker shifts the risk; it doesn't define it.
A soft marker shifts the probability slightly. It does not diagnose anything. Most babies with a soft marker are completely healthy.
The six soft markers you're most likely to see
1. Choroid plexus cyst (CPC)
What it is: A small fluid-filled space in the choroid plexus, the structure inside the brain's lateral ventricles that produces cerebrospinal fluid. CPCs can be unilateral (one side) or bilateral (both sides). They can be single or multiple. None of those distinctions change the clinical significance much in isolation.
How common: Around 1–2% of all second-trimester anatomy scans.
What it actually means: Almost always nothing. CPCs resolve on their own in the great majority of cases by 28 weeks. They have no effect on brain development or function. The historical association with Trisomy 18 was based on studies in high-risk populations; in low-risk pregnancies with reassuring first-trimester screening, an isolated CPC carries minimal additional risk.
What usually happens: The report mentions it. Your OB may not even raise it at the next appointment unless you ask. No follow-up scan is typically needed unless other markers are also present.
2. Echogenic intracardiac focus (EIF)
What it is: A small bright spot in the muscle of one of the heart's ventricles, usually the left. It's essentially a tiny calcium deposit in a papillary muscle. The heart itself looks structurally normal.
How common: 3–5% of all pregnancies in general populations; up to 30% in some East Asian populations, where it's considered a normal variant rather than a marker.
What it actually means: Functionally, nothing. The heart works exactly as it should. The historical association is with Trisomy 21, but the increase in risk from an isolated EIF in a low-risk pregnancy is very small. The structural assessment of the heart — four chambers, two outflow tracts, normal rhythm — is the much more important finding.
What usually happens: Noted in the report, often discussed briefly at the next OB appointment, no further action if everything else is normal.
3. Echogenic bowel
What it is: Bowel tissue that appears as bright on ultrasound as the surrounding bone. This can happen because of swallowed blood from earlier in pregnancy, cystic fibrosis carrier status in the parents, certain intrauterine infections (commonly CMV), placental insufficiency, or — rarely — a chromosomal condition.
How common: Around 0.5–1% of anatomy scans.
What it actually means: Echogenic bowel is the soft marker that warrants the most follow-up. It is not a diagnosis, but it does mean a workup — typically infection screening (CMV, toxoplasmosis), parental cystic fibrosis carrier testing, and a discussion of NIPT or amniocentesis. The good news: in many cases the workup comes back reassuring and the marker resolves later in pregnancy.
What usually happens: Referral to a fetal medicine specialist, blood tests, repeat scan in a few weeks. The conversation is more involved than for CPC or EIF.
4. Mild renal pelvis dilation (pyelectasis)
What it is: A slight widening of the renal pelvis — the funnel-shaped part of the kidney where urine collects before draining into the ureter. Mild is typically defined as 4–7 mm at the anatomy scan.
How common: Around 1–2% of pregnancies; significantly more often in male babies.
What it actually means: In most cases, nothing concerning. Many cases resolve on their own. Some persist and are checked with a postnatal ultrasound at a few weeks of age to make sure drainage is normal. The chromosomal association is weak in isolation, particularly with reassuring first-trimester screening.
What usually happens: Mentioned at the next OB appointment, often a follow-up scan at around 32 weeks to recheck, and a paediatric ultrasound after birth if it persists.
5. Short femur
What it is: The femur length measurement falling below the 5th percentile for gestational age, in the absence of overall growth restriction.
How common: Around 4–5% of scans by definition (it's a percentile), but only a fraction of these are reported as soft markers because most are explained by family height patterns or measurement variation.
What it actually means: Most often, family stature — short parents tend to have babies measuring smaller. Occasionally it's a measurement error that resolves on follow-up. Rarely, it's associated with skeletal dysplasia or chromosomal conditions, which is why it's on the soft marker list.
What usually happens: Often a follow-up scan in 4 weeks to confirm growth trajectory. If it's tracking with family stature and everything else is normal, nothing further.
6. Single umbilical artery (SUA)
What it is: The umbilical cord normally has two arteries and one vein. In SUA, only one artery is present.
How common: Around 1% of pregnancies.
What it actually means: An isolated SUA with normal anatomy on the scan is mostly a curiosity. It's associated with a small increase in chromosomal risk and a slightly elevated rate of growth restriction, which is why pregnancies with SUA usually get a growth scan in the third trimester. In otherwise normal anatomy, most babies with SUA are completely healthy.
What usually happens: Growth scan at around 32–34 weeks, normal antenatal care otherwise.
Why isolated soft markers usually mean almost nothing
The mathematical reason is called “likelihood ratios.” A soft marker shifts the probability of a chromosomal condition by a multiplier — for most markers, somewhere between 1.5 and 8. But if your starting probability (from first-trimester screening) was, say, 1 in 5,000, a multiplier of 5 still gives you 1 in 1,000. The marker shifts the number, but it doesn't define it.
This is why isolated soft markers are mostly noted and not acted on. The post-test probability remains low. The marker is documented for completeness, your OB calculates an adjusted risk, and life moves on. The conversation changes meaningfully only when multiple markers appear together, or when first-trimester screening was already elevated.
What to actually do if a soft marker appears in your report
- Don't Google the marker by name. The first three results will be worst-case-scenario forums. The actual clinical context — your first-trimester screening results, the rest of the scan, whether the marker is isolated — gets lost. Read this article first.
- Ask the right question. The question is not “is this serious?” The question is: “Given everything else on the scan and our prior screening, what does this marker mean in context?”
- Wait for the OB conversation. Your OB will calculate an adjusted risk based on the marker plus everything else they know. That number is the one to care about, not the marker on its own.
- Use Dadly if the report has terms you can't parse. Dadly's scan-report analysis breaks down each finding in plain English, with the context that forums and Google searches strip out. That's exactly what it's built for.
When soft markers really do warrant follow-up
Three situations change the picture meaningfully and are worth a serious conversation with your OB or a fetal medicine specialist:
- Multiple soft markers across body systems. Two or more, especially if they include echogenic bowel, suggest a more thorough workup.
- Elevated first-trimester screening or NIPT. A soft marker on top of a higher baseline risk shifts the picture more than the same marker on top of a low baseline.
- Echogenic bowel specifically. Even in isolation, this one tends to trigger infection screening, parental carrier testing, and a discussion of amniocentesis or detailed follow-up imaging.
In all three cases, the next step is usually a referral to a fetal medicine unit for high-resolution imaging and a longer conversation about the options. Many of these conversations end with reassurance. Some end with a clearer picture that helps the family plan. The right move is to be there, listen carefully, and ask the questions that matter.
Most soft markers mean almost nothing. A few mean something. The job is to know which is which — and that's a conversation with your OB, not Google.
Related reading
For the broader context of what happens at the scan and what each structure they're checking actually does, read the complete dad's guide to the 20-week anatomy scan. For the practical questions to ask in the room, see anatomy scan questions every dad should ask. And if your partner is going through a high-risk pregnancy and you're trying to make sense of a stream of reports, our piece on asking AI every question during a high-risk pregnancy walks through the lived experience of doing exactly that.
Dadly's scan-report analysis is built for moments like this. Upload the report, and Dadly walks you through every line — what each soft marker means, what the measurements imply, what to ask at the next OB appointment, and what's reassuring versus what's worth following up on. Join the waitlist at dadly.app/waitlist for early access.