The impact of intrauterine adhesions on endometrial receptivity in patients undergoing in vitro fertilization-embryo transfer

Objective To clarify whether intrauterine adhesions (IUAs) affect endometrial receptivity (ER) on the day of ovulation and to compare patients with mild and moderate-severe adhesions. Methods This prospective cohort study included 592 infertile women with IUAs who underwent frozen-thawed embryo transfer (FET). Patients were divided into groups with or without IUAs; and pregnant and nonpregnant populations based on whether a clinical pregnancy was achieved. The ultrasound ER parameters on the ovulation day were compared. Patients with IUAs were then divided into mild or moderate-severe IUA subgroups according to IUA degree. Results The proportions of patients with Type B plus Type C endometrial morphology (94% vs. 75%, P<0.001), an endometrial thickness >= 8mm (97% vs. 81%, P<0.001), an endometrial volume >= 2ml (94% vs. 67%, P<0.001), a frequency of endometrial peristalsis >= 2 times/min (84% vs. 53%, P<0.001), low subendometrial volume (11.54 +/- 2.94 vs. 9.57 +/- 2.35, P<0.001) and subendometrial vascularization flow index (VFI) values (2.70 +/- 3.10 vs. 2.23 +/- 2.23, P=0.033) and a low live birth rate (65% vs. 56%, P=0.039) were significantly higher in the group without IUAs than in the group with IUAs. The group with moderate-severe IUAs had lower proportion of patients with an endometrial thickness >= 8mm (73% vs. 89%, P=0.008) and an endometrial volume >= 2ml (58% vs. 78%, P=0.005), a lower frequency of endometrial peristalsis >= 2 times/min (42% vs. 65%, P=0.003), and low subendometrial volume (9.22 +/- 2.29 vs. 9.97 +/- 2.36, P=0.023) and subendometrial flow index (FI) (31.48 +/- 3.64 vs. 33.43 +/- 4.17, P=0.002) values than the group with mild IUAs; a high antral follicle count (AFC), basal follicle-stimulating hormone (FSH), and anti-M & uuml;llerian hormone (AMH) levels and an endometrial thickness >= 8mm were independent predictors of clinical pregnancy. Conclusion IUAs can affect ER on the ovulation day and the live birth rate during natural cycles. Moderate-severe IUAs have a greater impact on ER than mild adhesions do; however, if these adhesions are treated properly, they do not have adverse effects on the clinical pregnancy rate. A high AFC, basal FSH and AMH levels and an endometrial thickness >= 8 mm were found to be independent predictors of clinical pregnancy.