Retrospective analysis of the endometrial preparation protocols for frozen-thawed embryo transfers in women with endometrial polyps

We aimed to explore the clinical effects of the endometrial preparation protocol for frozen-thawed embryo transfer (FET) in women with endometrial polyps. This retrospective study was performed at the Reproductive Medicine Centre of the First Affiliated Hospital of Sun Yat-sen University between January 2015 and May 2018 involving women diagnosed with endometrial polyps by hysteroscopy. The freeze-all strategy was performed in controlled ovarian stimulation cycles followed by FET cycles. Endometrial preparation protocols included: (i) gonadotropin-releasing hormone agonist-hormone replacement therapy (GnRHa-HRT); (ii) hormone replacement therapy (HRT); (iii) natural cycle (NC); and (iv) ovulation induction (OI). Recurrence rate of polyps and clinical results were compared among the four groups. If polyp recurrence was found in ultrasound scans during the FET cycles, the embryo transfers were cancelled. The recurrence rate of polyps was lower in the GnRHa-HRT protocol [2.13% (2/94)] than in the other three protocols [6.15% (26/423), 6.7% (28/418), and 4% (1/25) in the HRT, NC, and OI, respectively; p = 0.038], showing statistically significant difference. Pregnancy, early pregnancy loss, and live birth rates among the four protocols were similar (p = 0.922, p = 0.171, and p = 0.072, respectively). The GnRHa-HRT protocol used for FET in women with endometrial polyps could reduce the recurrence rate of the polyps. In addition, we found that it did not decrease pregnancy or live birth rates.