Podcast Summary: Dr. Chapa’s OBGYN Clinical Pearls — "New CC #11: Positive HCG in the Non-OB/Non-Gyn CA Patient" (Jan 18, 2026)

Episode Overview

The episode centers on the new ACOG Clinical Consensus Number 11 (releasing February 2026), which addresses the clinical approach to a positive human chorionic gonadotropin (HCG) test in patients who:

• Are not pregnant
• Do not have gynecological malignancy (no gestational trophoblastic disease or ovarian germ cell tumor)

Dr. Chapa walks clinicians through the updated diagnostic pathway, stressing test interpretation nuances and reminding listeners: “Tests that we order have a consequence.” The episode aims to clarify differential diagnoses, appropriate next steps, and avoid missed cases of significant non-gynecologic disease.

Key Discussion Points & Insights

1. The "Weird" Positive HCG: Why This Matters (01:10–04:58)

• Dr. Chapa introduces the clinical challenge: “What do we do with these weird HCG results?” when pregnancy and gyn malignancy are ruled out.
• Stresses the consequence of indiscriminate test ordering and the importance of considering age-related HCG values.
• Memorable moment: Recurring playful riffs on “Phantom HCG,” likening it to “Phantom of the Opera” for comic relief.

Quote:
"Tests that we order... have a consequence. So if you're going to order something, be prepared to deal with a weird result and potentially going down a rabbit hole." (03:04 – Dr. Chapa)

2. Background: HCG Physiology & Interpretation (05:00–09:10)

• Quick refresher on HCG structure (alpha and beta subunits).
• Alpha subunit shared across LH, FSH, TSH, HCG; beta subunit is almost unique—distinguished by a unique C-terminal peptide.
• Beta subunit’s similarity to LH is why pituitary can be a source of HCG, especially in perimenopausal/postmenopausal women.

Clinical pearl:

• In perimenopausal or menopausal women, a slightly elevated HCG (not hundreds or thousands) can be physiologically normal due to pituitary release, especially if FSH/LH are elevated.
• Age-specific cutoffs: For postmenopausal patients, the “positive” threshold can be up to 14 IU/L (vs. 5 IU/L in reproductive age women).

Quote:
"Another potential cause of elevated HCG, especially in peri or postmenopausal women, is the pituitary." (11:13 – Dr. Chapa)

3. New Algorithm: First Steps in Evaluating Persistent Low-Positive HCG (15:11–18:40)

• Step 1: Confirm with a urine HCG:
  • If serum positive but urine negative → most likely heterophilic antibody interference (“Phantom HCG”).
  • "If the PP is negative, that's called a heterophilic antibody—the old term for that was the phantom hcg." (16:45)
• If urine is also positive for HCG, the test result is genuine, not artifact.
• Emphasizes confirming ovarian/source imaging to rule out missed gyn sources.

4. If Both Serum & Urine HCG Are Positive: The Differential (18:41–25:30)

Potential Causes:

• Pituitary origin (in older women, especially if FSH/LH elevated)
• Chronic kidney disease (reduced HCG clearance)
• Recent or remote bladder augmentation (enterocystoplasty)
• Familial HCG syndrome (rare genetic condition; ~1 in 60,000)
• Exogenous HCG use (weight loss, performance enhancement, Munchausen's syndrome)
• Non-gynecologic malignancy: Breast, GI, GU, lung, head & neck, osteosarcoma, testicular (in men)
  • "One of the causes you don't want to miss...a non-gynecological malignancy. Because HCG can be released as a paraneoplastic response." (22:50)

Notable clinical advice:

• Conduct full clinical review: recent mammogram, GI symptoms, weight loss, night sweats, etc., to screen for non-obvious cancers.
• Recognize that “false positive” results—if seen in urine too—require an explanation.

Quote:
"Don't just write off a quote-unquote false positive pregnancy test... if the urine also picks it up. So you can't explain it by the heterophilic antibody... You have got to look for a possible explanation." (23:10)

5. Rare and Esoteric Causes (20:40–22:10)

• Familial HCG syndrome:

  • Produces variant HCG, usually with absent or modified C-terminal peptide.
  • Diagnosis: ask about family history, may test relatives.

• Munchausen's syndrome:

  • Self-administration of HCG for attention-seeking reasons.

• Exogenous use:

  • Patients or athletes may take HCG intentionally.

6. Take-Home Algorithm (27:15–28:57)

Quick summary:

1. Persistent serum HCG+? Confirm with urine HCG.
2. Urine negative? Phantom HCG (heterophilic antibody interference)—reassure, no further workup.
3. Urine positive? Systematically rule out:
   • Missed pregnancy/gynecologic source (imaging, exam)
   • Pituitary source (FSH/LH, age-appropriate cutoffs)
   • Renal disease (creatinine/BUN)
   • Bladder augmentation
   • Familial syndrome (ask FHx)
   • Non-gyn malignancies (history, physical, targeted investigations)
   • Exogenous use/Munchausen's (history, review supplements/medications)

Quote:
"Get a positive HCG by serum, won't go away, get her pp (urine). PP is negative = phantom. If urine is positive... look for causes" (27:30)

Notable Quotes & Memorable Moments

• On clinical “boredom”:
  • "I've listened to other podcasts. They're so damn boring ... And we are definitely not boring. That's our mission. Give you good information and not be boring." (17:20)
• On “Phantom HCG” jokes: Multiple playful references, including musical cues and teasing quips with the producer.
• On newness and updates:
  • "Some things move fast in medicine, some things not so fast. Because the last time ACOG covered this was... November of 2002. Nothing like an update 20 years later. It's fine. It's all good." (10:18)

Timestamps for Key Segments

• Intro & Context / Why This Topic: 01:05 – 05:00
• HCG Physiology & Lab Cutoffs: 05:00 – 10:30
• Pituitary & Age-Specific Guidance: 10:30 – 15:11
• Algorithm Step 1 (Phantom HCG): 15:11 – 18:40
• Urine Positive Differential & Malignancy Risks: 18:41 – 25:30
• Esoteric & Rare Causes / Summary Algorithm: 25:31 – 29:10

Final Takeaways

• Treat persistent low-positive HCG results systematically; don’t assume all are false positives.
• Confirm “phantom” HCG with urine testing.
• If both blood and urine are positive, systematically rule out other causes—including non-gynecologic malignancies.
• Especially in older women, interpret HCG with age-appropriate cutoffs and hormonal context.
• Keep a broad, thorough differential—sometimes a positive HCG is the first clue to significant, even non-obstetric disease.

As Dr. Chapa summarizes:

"This was clinical consensus number 11 coming out February of 2026... It was about time." (28:55)

This episode delivers clinical pearls with clarity, humor, and enthusiasm—making even the rare “phantom” positive HCG a memorable and practical learning experience.