Unoperated endometriomas and ovarian response: comparable oocyte yield, fewer embryos

Design

Systematic review and meta-analysis of 13 observational studies (PROSPERO registered)

Population

Women with unilateral unoperated ovarian endometrioma undergoing ovarian stimulation, compared ovary-to-ovary

Primary outcome

Number of oocytes retrieved per ovary

Effect

Mean difference -0.72 oocytes (95% CI -1.45 to 0.02; I² = 97%; 11 studies, 560 patients)

This meta-analysis pooled 13 observational studies that compared the ovary with an endometrioma against the healthy contralateral ovary in the same woman during stimulation for IVF or ICSI. Using the other ovary as the control avoids differences between women.

Oocyte numbers were similar (mean difference -0.72, 95% CI -1.45 to 0.02; 11 studies, 560 patients), as were mature oocytes and good-quality embryos. The number of embryos formed was lower in affected ovaries (mean difference -0.72, 95% CI -1.39 to -0.05; four studies). Heterogeneity was very high for oocyte yield (I² = 97%).

The authors suggest that surgery before IVF should be weighed carefully, especially for small cysts. Most studies were observational, eight were retrospective, none was preregistered, and the effect of larger endometriomas remains uncertain.

• Do not assume a small, unoperated endometrioma will reduce the stimulation response.
• Weigh surgery against the risk to ovarian reserve before recommending cystectomy ahead of IVF.
• Document cyst size, since the data say least about larger endometriomas.
• Counsel that fewer embryos formed in affected ovaries in a small subset of studies.
• Decide jointly with the fertility team, as symptoms and suspicion of malignancy may still justify surgery.

Why it matters

It challenges the reflex to remove endometriomas before IVF, a step that itself can reduce ovarian reserve.

Don't overread it

Observational data with very high heterogeneity cannot show that leaving a cyst in place gives better live-birth rates.

The statistics, in plain English

The oocyte confidence interval just touches zero (upper limit 0.02), so the result is borderline rather than clearly null. An I² of 97% means the studies disagreed widely, so the pooled figure is an average of very different results and should be treated cautiously.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.