What could be the cause of an elevated anti‑Müllerian hormone (AMH) level in a 36‑year‑old woman with endometriosis who is taking Visanne (dienogest)?

Elevated AMH in Endometriosis with Visanne Treatment

The most likely cause of elevated AMH in this 36-year-old woman with endometriosis taking Visanne (dienogest) is the presence of a large endometrioma (>50mm), as recent evidence demonstrates a paradoxical positive correlation between endometrioma size and AMH levels, independent of medical treatment.

Primary Mechanism: Large Endometrioma Effect

The traditional understanding that endometriomas uniformly suppress AMH has been challenged by recent research. A 2026 study found that larger endometriomas (>50mm) were paradoxically associated with significantly higher AMH levels compared to smaller cysts 1. Specifically:

• Endometriomas ≤30mm: AMH 1.72 ± 1.26 ng/mL
• Endometriomas 31-50mm: AMH 2.23 ± 1.78 ng/mL
• Endometriomas >50mm: AMH 2.70 ± 1.69 ng/mL (p=0.01 vs. small cysts)

In multivariable analysis, cyst diameter independently predicted AMH levels (β=0.031, p<0.001) 1. This finding contradicts the widely accepted position that endometrioma growth progressively damages ovarian tissue and reduces AMH 2.

Dienogest (Visanne) Does NOT Elevate AMH

Postoperative dienogest treatment has no rescue or elevating effect on AMH levels 3. A 2023 study comparing patients receiving dienogest 2mg daily for 6 months versus no treatment after laparoscopic cystectomy found:

• Both groups experienced similar AMH reduction (65.5% vs 64.8% decrease at 3 months)
• No statistically significant difference in AMH recovery rates between groups (p=0.707)
• Dienogest neither prevented AMH decline nor accelerated recovery 3

Therefore, dienogest can be excluded as the cause of elevated AMH in this patient.

Alternative Consideration: Undiagnosed PCOS

The second most important differential is underlying polycystic ovary syndrome (PCOS), which can coexist with endometriosis 4. Women with PCOS have significantly higher AMH levels compared to normal ovulatory women due to increased numbers of pre-antral and small antral follicles 4.

Key Diagnostic Features to Distinguish PCOS:

According to international guidelines 4, PCOS requires 2 of 3 Rotterdam criteria:

1. Oligo/anovulation - Check menstrual pattern history
2. Clinical/biochemical hyperandrogenism - Measure free and total testosterone using gold standard assays 5
3. Polycystic ovarian morphology (PCOM) on ultrasound:
   • ≥20 follicles per ovary (2-9mm) using 8MHz transvaginal probe 4
   • OR ovarian volume ≥10mL 4

Critical caveat: AMH should NOT be used as a single diagnostic test for PCOS 4. The 2019 International Evidence-based Guidelines explicitly state that "serum AMH levels should not yet be used as an alternative for the detection of PCOM or as a single test for the diagnosis of PCOS" 4.

Diagnostic Algorithm

To determine the cause of elevated AMH in this patient:

1. Obtain transvaginal ultrasound to measure:

   • Endometrioma size (if >50mm, this likely explains elevated AMH)
   • Follicle count per ovary and ovarian volume (assess for PCOM)
   • Document presence of corpus luteum, cysts, or dominant follicles 4

2. Assess for PCOS features:

   • Menstrual cycle pattern (oligo/anovulation?)
   • Free and total testosterone levels 5
   • LH/FSH ratio (LH>FSH suggests PCOS) 5
   • Clinical signs of hyperandrogenism

3. Rule out functional hypothalamic amenorrhea (FHA) if amenorrheic:

   • FHA patients have low gonadotropins (LH and FSH <10 IU/L) 5
   • FHA can mask PCOS but typically shows low-normal AMH 6, 5
   • Check for eating disorders, excessive exercise, stress 5

Clinical Implications

Interpretation of AMH in endometriosis patients must be context-dependent 1. The presence of large endometriomas creates a paradoxical situation where AMH may be elevated despite potential ovarian damage. Clinical decisions regarding ovarian reserve should not rely solely on cyst size or AMH values 1.

Important Pitfalls to Avoid:

• Do not assume elevated AMH indicates good ovarian reserve in the presence of large endometriomas
• Do not diagnose PCOS based on AMH alone - requires full Rotterdam criteria 4
• Do not attribute AMH changes to dienogest - the medication does not affect AMH levels 3
• Stage III-IV endometriosis typically shows 40-48% lower AMH levels 7, so elevated AMH in this context is particularly noteworthy

The most biologically plausible explanation remains a large endometrioma (>50mm), which should be confirmed with imaging. If PCOM is also present on ultrasound with appropriate clinical features, concurrent PCOS should be considered.