Podcast Summary: Dr. Chapa’s OBGYN Clinical Pearls

Episode: New Data on MVP or AFI For Poly
Date: January 26, 2026
Host: Dr. Chapa
Main Theme:
This episode delves into the latest evidence comparing two methods for diagnosing polyhydramnios—Amniotic Fluid Index (AFI) and Maximal (or Deepest) Vertical Pocket (MVP/DVP)—in predicting adverse perinatal outcomes. Dr. Chapa discusses a new 2026 research letter from BJOG, alongside clinical practice guidelines, and provides practical recommendations for managing polyhydramnios.

Episode Overview

• Purpose: To evaluate whether AFI or MVP is superior in predicting adverse outcomes in pregnancies complicated by polyhydramnios, and translate new research findings into practical clinical guidance.
• Context: While MVP is preferred for diagnosing oligohydramnios due to its superior prediction of adverse outcomes, it's unclear if the same applies to polyhydramnios.

Key Discussion Points & Insights

1. Background: The Oligohydramnios and Polyhydramnios Debate

• Oligohydramnios:

  • Practice guidelines (ACOG, SMFM): Use MVP for diagnosis (≤2 cm; normal >2 cm)
  • MVP is preferred over AFI for 'oligo' as it reduces false positives without compromising detection of adverse outcomes.

• Polyhydramnios:

  • Uncertainty: Lack of high-quality data on whether AFI or MVP better predicts morbidity.
  • Definitions:
    • MVP: ≥8 cm = polyhydramnios (mild: 8–11 cm, moderate: 12–15 cm, severe: >16 cm)
    • AFI: ≥24 cm = polyhydramnios (mild: 24–30 cm, moderate: 30–35 cm, severe: >35 cm)
  • Common question:
    • Should we use AFI or MVP for diagnosing polyhydramnios with respect to predicting adverse outcomes?

“We don’t know right now if maximal vertical pocket or AFI is better in finding out perinatal morbidity related to polyhydramnios. Does that make sense?”
— Dr. Chapa [03:07]

2. Deep Dive: The New BJOG Research Letter (Jan 2026)

• Study Details:
  • Authors from Rome, Newark, and Philadelphia (including Vince Vicenzo Brigella).
  • Systematic review: 133 studies screened; only 5 non-RCTs eligible (~5,319 patients).
  • Major limitation: Only 1 retrospective study reported neonatal outcomes.
• Main Finding:
  • Neither method (MVP or AFI) is superior in predicting adverse perinatal outcomes for polyhydramnios.
  • Both are equally linked to adverse outcomes; method of measurement doesn’t impact clinical prediction.
  • Key Quote:

    “The short of it was in this publication, whether you use an MVP or an AFI … it didn’t matter. Both of them were linked to adverse perinatal outcomes.”
    — Dr. Chapa [15:30]

  • The study calls for urgent, higher-quality RCTs to guide practice.

“What it is, is a valiant attempt to answer a question. What it isn’t is a real, firm, solid, high-quality data answer.”
— Dr. Chapa [07:58]

3. Comparative Evidence: Oligo vs. Poly

• For Oligohydramnios:
  • MVP is proven superior for clinical prediction.
  • AFI should not be used to define oligo; may over-diagnose without improving outcomes.
• For Polyhydramnios:
  • Choice of AFI or MVP is not clinically significant for predicting perinatal morbidities.

“Unlike for oligo, it really doesn’t matter if you use the AFI or the maximal vertical pocket. The morbidities were reflected in either determination method.”
— Dr. Chapa [15:54]

4. Clinical Recommendations: SMFM/ACOG Guidelines (Console Series #46, 2018)

Dr. Chapa summarizes six practical recommendations for managing polyhydramnios:

Six Key Management Points

[17:00-19:43]

1. Diagnosis:

   • Polyhydramnios in singletons may be defined by either MVP or AFI.
   • For twins: Use MVP.

   “So even in SMFM’s guidance … you can do one or the other. Because the truth is … it really just doesn’t matter.”
   — Dr. Chapa [17:00]

2. Amnioreduction:

   • Consider only for severe maternal discomfort/dyspnea in severe polyhydramnios, not for mild/moderate cases.

3. Indomethacin:

   • Should not be used solely to decrease amniotic fluid in polyhydramnios.

4. Antenatal Surveillance:

   • Not required for mild idiopathic polyhydramnios (MVP 8–11cm, AFI 24–30cm) in the absence of other factors.

5. Labor & Delivery Timing:

   • Allow labor to occur spontaneously at term for mild idiopathic polyhydramnios; do not induce <39 weeks without other indications. Delivery mode per usual obstetric indications.

6. Setting for Delivery:

   • Severe polyhydramnios: Deliver at tertiary center due to risk of anomalies. Even if anatomy is normal, unrecognized functional (e.g., neuromuscular) issues can exist.

Notable Quotes & Memorable Moments

• Refrain Throughout:

  • The running joke/quote in this episode:

  “It just doesn’t matter. It just doesn’t matter. It just doesn’t matter.”
  – Bill Murray in "Meatballs" & Dr. Chapa’s repeated use [04:11, 16:45, 18:19, 22:25]

• On Disappointment with Data:

  “We had high hopes for this … but we have … there just really isn’t high quality RCTs to tell us which one’s better.”
  — Dr. Chapa [06:58]

• On Clinical Practice:

  “For oligo, we’ve got solid evidence… For poly, we just don’t.”
  — Dr. Chapa [10:01]

• On Fetal Anomalies in Polyhydramnios:

  “Even if the anatomical survey is normal, the baby may have a neuromuscular issue that can prevent proper swallowing. You cannot see that on ultrasound.”
  — Dr. Chapa [21:13]

Timestamps for Key Segments

• [03:00] Setting up the clinical question: MVP vs. AFI for polyhydramnios
• [06:00] Overview of the BJOG research letter and its limitations
• [08:20] Review of oligo definitions and evidence supporting MVP for low fluid
• [11:35] Definitions of polyhydramnios (MVP & AFI thresholds)
• [15:30] Summary of study findings: “It didn’t matter” between methods
• [17:00–19:43] SMFM/ACOG six management recommendations for polyhydramnios
• [21:13] Discussion on diagnosing causes of polyhydramnios and tertiary care
• [22:25+] Reiteration of main lesson with humor (“It just doesn’t matter”)

Tone & Final Thoughts

• Approachable, practical, and laced with humor:
  • Dr. Chapa's energetic delivery and use of running jokes keep the content engaging ("It just doesn’t matter!"), but he never loses focus on clinical utility.
• Clinical Relevance:
  • Emphasized being up-to-date and pragmatic.
  • Advocates for evidence-based practice, acknowledges gaps in data, and distills actionable guidance.
• Closing:
  • Final reminder of the main point: For polyhydramnios, use either AFI or MVP—they’re both valid.

Take-Home Message

For polyhydramnios in singleton pregnancies, it does not matter whether you use AFI or maximal vertical pocket for diagnosis—both are similarly associated with adverse outcomes. Practice should be guided by existing consensus recommendations, while awaiting better quality research.

“It just doesn’t matter. It just doesn’t matter.”
– Dr. Chapa & Bill Murray ("Meatballs") [Throughout]