Comparison of frozen-thawed embryo transfer protocols in patients with previous cycle cancellation due to uterine peristalsis: a pilot study

BACKGROUND/AIM: To investigate the optimal protocol for frozen-thawed embryo transfer (FET) cycles in patients who previously had a cycle cancellation due to uterine peristalsis (UP). MATERIALS AND METHODS: Thirty-four patients with previous embryo transfer (ET) cancellation due to UP during artificial cycle (AC) were included retrospectively. In the proceeding cycle, endometrium was prepared with AC (n: 23) in AC-FET group or with stimulated cycle that contains letrozole (L) (n: 11) in L-FET group. Intravenous bolus dose of 6.75 mg atosiban (Tractocile; Ferring Pharmaceuticals, Switzerland) injection was performed to all patients of AC-FET group due to UP ≥ 4/min on the planned ET day of proceeding cycle. Atosiban was not used in L-FET group. Primary outcome was live birth rate (LBR) per ET. Secondary outcomes were clinical pregnancy rate (CPR) per ET, implantation rate (IR), cycle cancellation rate. RESULTS: The baseline characteristics such as age, body mass index, antral follicle count, duration of infertility, and the number of prior in vitro fertilization attempts of each group were similar. The IR, CPR per ET, LBR per ET, CPR per cycle and LBR per cycle were significantly higher; cycle cancellation rates were significantly lower in L-FET group as compared to the AC-FET group. CONCLUSION: Endometrial preparation with letrozole significantly improves CPR and LBR in FET cycles of patients with previous cycle cancellations due to UP.