Association between endometriosis and endometrial polyps: a systematic review and meta-analysis

Endometriosis and endometrial polyps are oestrogen-dependent conditions that frequently co-occur, yet their combined prevalence remains unclear. This study synthesized data on the prevalence of endometrial polyps in women with endometriosis and vice versa. Systematic searches of PubMed, Embase and Scopus were conducted up to 1 October 2024. Observational studies reporting the prevalence of endometrial polyps in women with endometriosis, and vice versa, were included. Random-effects models calculated pooled proportions and risk ratios (RR) with 95% CI. Risk of bias was assessed using the Newcastle-Ottawa scale, and evidence/certainty was graded using the Grading of Recommendations Assessment, Development and Evaluation guidelines. The protocol was registered in PROSPERO (CRD42024595167). Twenty-two studies with 10,928 patients (8154 women with infertility) were included. Women with endometriosis (1757 patients) had a significantly higher risk of endometrial polyps (RR 2.18, 95% CI 1.58-3.00; I² = 83.5%; P < 0.001), and women with polyps (2130 patients) had a significantly higher risk of endometriosis (RR 2.05, 95% CI 1.61-2.62; I² = 82.5%; P < 0.001), compared with controls (5590 and 5217 patients, respectively). Subgroup analyses by infertility status and disease stage confirmed these findings. A gradient effect showed a significantly higher risk of endometrial polyps in women with stage III-IV endometriosis compared with women with stage I-II endometriosis (RR 1.19, 95% CI 1.08-1.32; I² = 0.0%; P < 0.001). Endometriosis and endometrial polyps are strongly associated, particularly in women with infertility. Despite low-quality evidence, these findings emphasize the importance of better detection and targeted interventions to enhance fertility outcomes.