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cfDNA: Jan 2026 Practice Advisory

Sat Jan 10 2026

Summary

Podcast Summary: Dr. Chapa’s OBGYN Clinical Pearls

Episode: cfDNA: Jan 2026 Practice Advisory
Date: January 10, 2026
Host: Dr. Chapa
Topic: New ACOG & SMFM Guidance on Cell-Free DNA (cfDNA) Screening for Fetal Chromosomal Abnormalities

Overview

This high-yield episode reviews the latest 2026 ACOG Practice Advisory on cfDNA for screening fetal chromosomal abnormalities, which updates and supersedes Practice Bulletin 226. Dr. Chapa provides practical pearls for medical students, residents, and clinicians on what has changed—especially regarding screening for sex chromosome abnormalities (SCAs)—and what remains the same. The episode drills into the science, accuracy, counseling, and clinical management implications of these new recommendations, connecting them to SMFM's November 2025 Consult Series 74.

Key Discussion Points & Insights

1. The Fast-Paced Nature of Medicine and New Guidance

Medicine and science are ever-evolving, and so clinical practices are regularly updated in response to new evidence.

“Medicine moves fast. Now, the reason medicine moves fast is because science, on which medicine is based, also moves fast.” (00:36)

2. What's Changed: The 2026 ACOG Practice Advisory

January 2026 saw a new ACOG Practice Advisory on “Screening for Fetal Chromosomal Abnormalities,” replacing Practice Bulletin 226.
- Driven by new recommendations and data, particularly from SMFM Consult Series 74 (Nov 2025), now endorsed by ACOG.

3. cfDNA Screening: What Remains the Same (10:00–12:30)

cfDNA is still recommended for trisomies 21, 18, and 13 (Down, Edwards, and Patau syndromes).
Offerable to all patients (not just high-risk) following proper pre-test counseling.
cfDNA is approved and accurate for these aneuploidies in both singleton and twin gestations.

“Trisomy 18, 13, 21 using cell free DNA. Super good. Whether you're multiple or twins…” (12:45)
Not enough data for higher-order multiples (triplets or more): cfDNA not recommended.
Still not recommended for microdeletions or large genome-wide copy number variants.

“Micro deletion screening using cell free DNA is still not recommended.” (07:50, 12:30)

4. Sex Chromosome Aneuploidies (SCA) Screening: The Big Change—OPT-IN Required (12:30–18:20)

SCA screening (Turner, Klinefelter, Triple X, Jacobs, etc.) is no longer “check the box”:
- Patients must opt-in after explicit counseling on the test’s limitations and clinical implications.
Why opt-in? The accuracy (positive predictive value, PPV) for SCA with cfDNA is substantially less than for common autosomal trisomies.
Clinicians must explain:
- Higher false positive rate for SCA (due to maternal mosaicism, confined placental mosaicism, etc.).
- Specific limitations differ from trisomies 21/18/13.
“By asking them to opt in, it now puts the challenge and the task on us to do our job, which is tell them the limitations of cell free DNA for sex chromosome abnormalities.” (03:45)

5. SCA: Test Accuracy & Counseling Pearls (18:20–27:00)

PPV for SCA is variable and generally lower than that for autosomal trisomies:
- Turner syndrome (45,X): PPV ~32%
- Triple X (47,XXX): PPV ~57%
- Klinefelter (47,XXY): PPV ~67%
- Other rare variants can vary
Maternal mosaicism is a key reason for false positives—approx. 8.6% incidence in one study.
Test is much more sensitive for Y chromosome abnormalities than X chromosome:

“Cell free DNA is much more sensitive and specific for disorders involving the Y chromosome than those involving the X chromosome, because it's living in a sea of X chromosomes, which is the mother.” (24:15)
Other causes for abnormal results include maternal cancer (rare), transfusions, transplants, or even fibroids.
Clinical pearl: Always interpret SCA results in context; heavily weigh patient age and result-specific PPV.

6. What To Do with an Abnormal SCA Result (27:10–32:00)

First step: Reassure and counsel patient about high false positive rate.
Next steps:
1. Consider diagnostic fetal testing (e.g., amniocentesis) to confirm.
2. If the result involves X chromosome (Turner or Triple X), consider maternal karyotype to check for mosaicism.
3. Involve genetics and/or MFM specialists as needed.
Always review the specific PPV for the exact abnormality detected—each lab report includes this crucial statistic.

7. cfDNA for Fetal Sex Determination—NOT for Nonmedical Use (32:00–34:10)

Over-the-counter or “direct-to-consumer” (DTC) tests available for fetal sex are NOT recommended for nonmedical, entertainment-only purposes due to:
- Potential for misleading results and lack of pre-test counseling.
- Tests target only Y chromosome detection—not a substitute for full SCA screening.
“The non medical use of cell free DNA solely for fetal sex determination is not recommended.” (34:10; also 06:20, 33:30)
Analogy: 3D ultrasounds are legitimate clinical tools but should not be used as "keepsake" without proper counseling.

8. Practice Recommendations Recap (35:00–end)

Eight key recommendations:
1. Offer cfDNA screening for trisomies 21, 18, 13 to all patients with pre-test counseling.
2. SCA screening must be opt-in with explicit, documented counseling.
3. Do NOT use cfDNA for microdeletions or large genome-wide deletions/duplications.
4. cfDNA for trisomies appropriate in twins (but NOT for SCA or higher-order multiples).
5. If abnormal SCA result: confirm with diagnostic test and consider maternal testing.
6. Over-the-counter cfDNA as entertainment or for solely sex determination is not endorsed.
Sensitivity, specificity, and positive predictive value are not interchangeable—understand and explain limitations to patients.

Notable Quotes & Memorable Moments

“The non medical use of cell free DNA solely for fetal sex determination is not recommended.” (Host quoting SMFM/ACOG, 06:20, 34:10)
“By asking them to opt in, it now puts the challenge and the task on us to do our job, which is tell them the limitations of cell free DNA for sex chromosome abnormalities.” (03:45)
“[For SCA] The accuracy...is not as good as it is for autosomal trisomies. And that's the catch.” (20:45)
“Cell free DNA is much more sensitive and specific for disorders involving the Y chromosome than those involving the X chromosome.” (24:15)
“Microdeletion screening using cell free DNA is still not recommended.” (07:50, repeated multiple times as “Say it twice!”)

Humor:

“It’s science. As Ron Burgundy would say.” (throughout)
“If you don’t know who Ron Burgundy is…that’s tragic!” (09:59)

Timestamps for Critical Segments

00:36: Introduction to new ACOG Practice Advisory
03:45: The rationale and mechanics behind opt-in for SCA screening
09:59: Recap on what’s unchanged in aneuploidy screening recommendations
12:30: Clarification on singletons, twins, and higher-order multiple gestations
18:20: Detailed discussion on SCA counseling, test accuracy, and maternal mosaicism
27:10: Stepwise management of an abnormal SCA screening result
32:00: Direct-to-consumer fetal sex testing and official recommendations
34:10: Quote reiteration: cfDNA not for pure fetal sex determination use
35:00: Final recap of major practice points

Language & Tone

Dr. Chapa’s delivery is energetic, colloquial, and practical—laced with humor (“It’s science!”), analogies, and direct advice aimed at clinicians in the trenches, students, and residents.
Repetition is used intentionally to reinforce key clinical pearls.

Take-Home Clinical Pearls

cfDNA remains the gold standard for trisomies 21, 18, 13—offer to all, with counseling.
Screening for sex chromosome aneuploidies now requires specific, documented opt-in consent (not automatic).
Do NOT use cfDNA for microdeletion screening or for nonmedical fetal sex determination.
False positives for SCA are far more common than with trisomies, mainly due to maternal factors.
Abnormal SCA results require confirmatory diagnostic testing and possibly maternal karyotyping.
cfDNA in twins OK for trisomies, NOT for SCA; NOT for higher-order multiples.
Always counsel—science is powerful, but it must be used responsibly.

End of Summary.

For further details and specific scenarios, listen to Dr. Chapa’s OBGYN Clinical Pearls, and refer directly to the 2026 ACOG Practice Advisory and SMFM Consult Series 74.

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Transcript

A (0:00)

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B (0:36)

Podcast family as is the tagline for this show, medicine moves fast. Now, the reason medicine moves fast is because science, on which medicine is based, also moves fast. It's always being tested, it's being updated, we're figuring out more information. So as science changes, changes, medicine changes, it's science. So that's a good thing because we don't live in a humdrum, you know, that's how I used to do it, world. Things are always on the move and that's a good thing. For example, even though we've had multiple guidances on screening for chromosomal abnormalities in the past, both from the American College of Medical Genetics, ACOG and smfm, and a variety of other sources, things are always moving, like in January of 2026. Now, as point of reference, we are doing this in January 2026, but ACOG this month has released a practice advisory that's called the pa, the title of which is Screening for Fetal Chromosomal Abnormalities. Now, this is actually going to replace the previous guidance from the college, which was practice bulletin 226. Okay, now let me, let me tell you how all this worked out. Okay? Back in November of 2025, just at the end of last year, the SMFM released console series 74, which is going to be our main focus in this episode. Console series 74, that is cell free DNA screening for anuploid is now, at that time, ACOG endorsed it. Now, trust me, from my time at the board, those words mean something. Endorsed means, sure, we'll stand with you, but we just won't say anything yet. We'll just, we'll stand it with you. Okay, so we put a little stamp like, yes, we've seen this. We're okay with this. Boom. Little stamp goes on it. However, that later can get adopted into a practice advisory, which is what happened here January 2026, with the new one titled Screening for Fetal Chromosomal Abnormalities. Now, why did it change? Because science is always on the move. It's science. And that's a good thing. Now, there are a couple of things that aren't gonna go anywhere that didn't change. Like, like, yes, it is still the most accurate. So free DNA is still the most accurate for chromosomal disorders like chromosomal trisomy 18, 13 and 21. That's a no brainer. But the big focus here guys, the big change really has to do with SCAs. SCAs, sex chromosome abnormalities. And we're going to focus on this. We're going to talk about whether this should be just offered to everybody, willy nilly. Just, just check the box part of your cell free DNA screen for 13, 18 and 21. Or should patients have to actually opt in for it? Now let me explain. Opt in mean it's not universal, already set, they have to opt out. It's just the opposite right now. It's not included. You have to ask them do you want sex chromosome abnormality screening? Which ideally they should say yes. However, by asking them to opt in, it now puts the challenge and the task on us to do our job, which is tell them the limitations of cell free DNA for sex chromosome abnormalities. Which are different guys. Which are different than the limitations for 13, 18 and 21 sex chromosome abnormalities. Those results are just not at the same level of accuracy as they are for autosomal trisomies. We're going to explain why the positive predictive value depends on what the thing finds, if something is abnormal, and how to counsel a patient with that. We're also going to talk about what to do once you have a sex chromosome abnormality. Well, what do we do with that? We're going to touch down that in very quickly and then we're going to get into this question. Even though there are commercially available products where you can go to the store right now, because science is phenomenal, it should be open to everyone. You can buy a kit that you can self do it at home to collect and then send in to a lab to let you know, is your child a boy or a girl. These are commercially available. All right, so you can do OTC as over the counter direct to consumer testing for fetal sex as a commercial slash entertainment thing. There's actually something in the SMFM guidance about that and whether that is recommended or not. And as you can guess, it's not recommended because of the limitations of sex chromosome abnormality testing. And then what to do with the result if something comes out, a little whack. Now when you do an over the counter test, it's only looking for the presence of the Y chromosome. Okay, So I want to make this thing very clear from the intro. Determining fetal sex is one thing, looking for sex chromosome abnormalities is the other thing. Those are very different. They're related but they are different. Okay, so we're going to get into this because the science is similar because it has to do with the Y chromosome, but at the same time it's different because it's much more involved when you're looking for sex chromosome abnormalities versus just doing the screen basically for the Y chromosome. Very similar to like 3D ultrasound. 3D ultrasound, it really shouldn't be used for a keepsake. Okay. 3D ultrasound is a medical test looking specifically designed to look for fetal anomalies to better characterize something found on 2D ultrasound. But of course, 3D ultrasound is used as something to memorialize as a memento. I get that. And not necessarily against it. I am against doing it without proper counseling. And that's what we're getting at here. Just as 3D ultrasounds can find things sometimes as a memento and you're like, oh, doing these over the counter direct to consumer tests for just for fetal sex can find some things or can muddy issues versus looking for a sex chromosome abnormality. So we're going to talk about this because there's a specific section in this committee opinion. I'm sorry, in this new console series from FMFM that addresses this. Okay. And the specific title, it's a little paragraph towards the end. We're quickly going to summarize it. It's very clear. The title is what basically what do we do with this technology, this science for commercialization. Okay. And it's much more deeper than just looking for fetal sex. It is a genetic test that's meant to look for anomalies. Well, we're going to talk about it. So again, this is all based on console series number 74 from SMFM, which ACOG endorsed back in November and now has issued a practice advisory. Some things have not changed. Micro deletion screening using cell free DNA is still not recommended. So let me say that again. I know some of us like to click that little box for microdeletion testing. If we're worried about microdeletion testing, they need a diagnostic test. Cell free DNA is a screening test is still too many questions for microdeletion screening. Okay, so we're going to get into this. We're going to talk about what didn't change, what did change, and then how results for an abnormal sex chromosome abnormality, how those results for an abnormal result should be managed. What should we do next with that? Okay, so that's basically where we're going. Oh, here it is. Sorry, I just popped up. What is the role of cell free DNA in fetal sex determination, I.e. section 2.16 in the console series. We're going to talk about that. Even though, as we've already alluded to, it's not recommended as a direct to consumer test. As you find out if it's a boy or girl, that's kind of a misuse of the science. Quote. The non medical use of cell free DNA solely for fetal sex determination is not recommended. End quote. Sorry, guys, I know that's a bummer. I know patients would like to do that and they totally can. And I am 100% pro ca. Capitalist baby. I think it's a great idea for a company to do with unfortunately, not a lot of counseling. And that's one of the issues. Because science, of course, shouldn't be abused. It should be respected. It's science. It's science, as Ron Burgundy would say. All right, podcast family, think I've set it up enough. We're going to talk about the practice advisory number 74, which really has to do with console series number 74 from SMFM, which ACOG endorsed, thank you very much. In November of 2025. I set it up enough. We will be right back.