Podcast Summary: Elevated msAFP but Normal Fetal Anatomy – What Now?

Podcast: Dr. Chapa’s Clinical Pearls
Host: Dr. Chapa
Episode Date: October 3, 2025

Episode Overview

This episode dives into the clinical conundrum: What should practitioners do when maternal serum alpha-fetoprotein (msAFP) is elevated, but the fetal anatomy scan is normal? Dr. Chapa unpacks updated evidence, ACOG guidance, and practical steps for OB/GYN providers, students, and residents.

The episode is lively and conversational, staying true to Dr. Chapa’s mission to make medical education “clinically relevant, engaging, and FUN.”

Key Discussion Points & Insights

1. Background: msAFP in 2025

• Evolution of msAFP Testing

  • Initially used as an isolated marker for fetal aneuploidy (1970s), msAFP has since been integrated into the triple, then quad screens.
  • Cell-free DNA (cffDNA) has become the norm for aneuploidy, but it does not screen for body cavity defects.

• Current ACOG Guidance ([06:34]):

  • Two main approaches to screening for congenital malformations:
    1. Detailed fetal ultrasound at 18–22 weeks (a “level 2” anatomy scan)
    2. msAFP testing, either alone or as an adjunct

• Dr. Chapa's Approach:

  • His team routinely performs both level 2 sonograms and msAFP for a double screening (“a backup to the eyeballs”).
  • Peak accuracy for msAFP: 18–20 weeks (acceptable window: 15–22 weeks).

“We do a full anatomy, of course, at 18 to 22 weeks or should they present later... But we also add MSAFP in the correct time frame.” (07:39)

2. What if msAFP is Elevated and Anatomy Scan is Normal?

• Abnormal: msAFP ≥ 2.5 multiples of the median (MoM)
  • Next Step: "What are we supposed to do now?" (10:46)

Key Points

• Primary Role of msAFP:
  • Detects neural tube defects and some abdominal wall defects.
  • With robust and experienced sonographers, the ultrasound is usually highly reliable (missing a neural tube defect becomes <0.5%; some say <0.05%).

“If you have a negative anatomical survey, that's phenomenal...anywhere from 99.5% sure to some say 99% sure. So really darn good.” (28:38)

• But: Persistent msAFP elevation without detectable fetal anomalies is a strong flag for increased risk of adverse pregnancy outcomes.

3. Associated Risks with Elevated msAFP & Normal Ultrasound

• It can flag future complications even if immediate fetal anatomy is normal.
• Elevated msAFP is statistically linked to ([19:24]):
  • Preeclampsia
  • Placental abruption
  • Fetal growth restriction (FGR)
  • Preterm delivery
  • Increased perinatal mortality

“That is a flag that without question is an increased risk for some adverse perinatal outcomes, including preeclampsia, placental abruption, preterm delivery, fetal growth restriction, and even some increase in perinatal mortality.” (19:24)

Clinical Pearl

• Surveillance is recommended:
  • Follow fetal growth every 4–6 weeks via ultrasound.
  • Monitor for preeclampsia and other complications.
  • Consider starting low-dose aspirin if not already on it (and no contraindication), as there may be time to benefit (preferably before 28 weeks) ([21:40]).

4. Where is the msAFP Coming From?

• If not from a body cavity defect... it’s often the placenta.
• Mechanism:
  • Placental dysfunction causes increased leakage/permeability, leading to more AFP crossing into maternal serum.
  • Root cause: Frequently related to oxidative stress and abnormal placental angiogenesis.

“The short answer is... that the placenta is janky. All right, the placenta is all janked up, right? The placenta is not good. Why? And it has to do with... oxidative stress.” (34:24)

5. What Should Providers Do?

Diagnostic Steps & Management

• DO NOT re-order the AFP as a tumor marker (common error; use only the test for neural tube defect risk, not for cancer marker).

  “Don't order that [tumor marker]... it's got to be AFP for neural tube defect assessment.” (15:17)

• No need to repeat msAFP if obtained in the optimal window with accurate dating and anatomic US is normal.

• Next Steps:

  • Reassure: Risk of missed neural tube/major anomaly is extraordinarily low with normal detailed scan
  • Initiate/continue growth surveillance: Ultrasound every 4–6 weeks for FGR
  • Monitor blood pressure: Watch for signs of preeclampsia
  • Start/continue low-dose aspirin (<28 weeks, if not contraindicated)
  • No routine need for NST/BPP unless FGR or other indication develops
  • Consider placental evaluation at delivery if msAFP was high without another cause

Notable Quotes & Memorable Moments

“We also do that as a double check for certainty. So number one, we're double checking anything that we're not seeing with a body... And then number two, there is plenty of data... in patients who have an elevated MSAFP level with a normal fetal anatomy scan, that's a flag.” (11:18)

“The reason that maternal serum alpha fetal protein is elevated—even in the cases of normal body body cavity evaluation with ultrasound—is that... the barrier, that’s the placenta, is janky. So it allows for a lot more weepage and seepage... it’s a sign of placental dysfunction.” (34:24)

“What do we do now? You can surveil fetal growth. You can start the patient on aspirin, you can monitor blood pressures. And it’s all about patient awareness.” (37:20)

“Please don’t say, ‘Well, your train’s off the rails, honey.’ ... No, no, no, no. This is just relative risk... it doesn’t mean that is 100%.” (39:12)

Key Timestamps

• 00:00–04:25 – [Intro and Ads skipped]
• 04:25–10:56 – msAFP: What it is, why still relevant, test windows, and screening approaches
• 10:56–19:24 – Double screening rationale, reliability of ultrasound, and when msAFP flags concern
• 19:24–25:05 – Risks associated with elevated msAFP in the setting of normal anatomy; clinical management pearls
• 25:05–34:24 – Surveillance strategies, aspirin use, reassurance vs. concern
• 34:24–39:30 – Where does the unexplained msAFP come from? The ‘janky placenta’ and placental dysfunction explanation
• 39:30–End – Practical wrap-up, clinical approach, and encouragement

Summary Table: What To Do When msAFP is Elevated but Fetal Anatomy is Normal

| Step | Details | |-----------------------------------------|-------------------------------------------------------------------------| | Confirm correct test & timing | msAFP for NTD, at 15–22 weeks (ideally 18–20); accurate dating crucial | | Review detailed anatomy scan | If normal, risk of major malformation is extremely low | | Assess msAFP value | Elevated = ≥2.5 MoM; ≥3 MoM more concerning | | Counsel about risks | Increased risk: preeclampsia, FGR, abruption, preterm birth | | Surveillance | Growth ultrasound q4–6 weeks; BP monitoring | | Consider aspirin | If <28 weeks and not already on it; barring contraindication | | No NST/BPP unless issues develop | Not indicated just for msAFP elevation | | Placental evaluation after delivery | Consider if msAFP never explained by anomaly |

Clinical Pearls Recap (from Dr. Chapa)

• Best Practice: Combine Level 2 anatomy scan with msAFP where possible
• If msAFP is elevated but scan is normal: It’s a placental red flag, not a false positive
• Proactive management and patient counseling will help mitigate risks
• Don’t ignore it—act, but also reassure

Episode Tone & Final Remarks

Dr. Chapa’s tone is warm, knowledgeable, and peppered with humor (“the placenta is janky”). He emphasizes practical, actionable steps and drives home the value of combining old and newer testing modalities for optimal prenatal care.

“Elevated msafp, but normal fetal anatomy. What next? Well, we just finished and wrapped that up in this episode.” (44:08)

For further reading: Dr. Chapa references key ACOG bulletins and promises related journal articles in the show notes.

Bottom Line:
When facing elevated msAFP and a normal fetal anatomy scan, don’t panic but don’t ignore it. Step up fetal surveillance, educate your patient, work with your team, and use this as a flag for possible placental dysfunction and related risks.

End of Summary