Purpose: Metformin has been shown to be an effective treatment for anovulatory polycystic ovary syndrome (PCOS) patients in terms of menstrual cyclicity, ovulation, and pregnancy, as well as reduction of early miscarriage rate. The aim of the study is to assess the effect of metformin on the endometrial vascular indices in anovulatory obese PCOS women using three-dimensional power Doppler sonography (3DPDUS).

Methods: A prospective study was set to determine the beneficial effects of metformin on PCOS patients. 90 anovulatory obese PCOS patients were compared with another 90 healthy volunteers who were age- and body mass index-matched (control group). PCOS patients were treated with metformin (Glucophage) 500 mg 3 times a day for 3 months. Assessment of the endometrial thickness and volume, uterine Doppler indices, and Doppler vascular indices of the endometrium and subendometrium in the periovulatory and midluteal phases were performed with 3DPDUS.

Results: There was a significant increase in the endometrial thickness, endometrial volume, and endometrial and subendometrial vascularity indices (vascularization index, flow index, vascularization flow index) after 3 months of metformin treatment in PCOS women.

Conclusions: Metformin, owing to its metabolic, endocrine, vascular, and anti-inflammatory effects,improves endometrial receptivity.