Does endometrial injury improve implantation of frozen-thawed embryos?

To investigate whether endometrial injury (EI) increases pregnancy rates in subjects undergoing frozen-thawed embryo transfer (FET) cycles.

We conducted a prospective study of 80 consecutive subjects at a private fertility center. All women were undergoing frozen embryo transfer after one or more unsuccessful in vitro fertilization and embryo transfer cycle(s). Subjects in the experimental group underwent endometrial biopsy in the luteal phase of the cycle preceding the frozen embryo transfer cycle. The primary outcomes were chemical and clinical pregnancy rates.

The 40 subjects who underwent EI in the cycle preceding their FET cycle were compared with 40 controls. There were differences in the groups' baseline characteristics; the average age was slightly higher and the duration of infertility was longer in the EI group. Chemical pregnancy rates between the two groups were similar, 27 % (range 17-40 %) in the injury group and 26 % (16-40 %) in the control group (OR for chemical pregnancy = 1.05, 95 % CI 0.42-2.12). The difference in clinical pregnancy rate was not statistically significant: 40 % (25-57 %) in the injury group versus 33 % (19-49 %) in the control group (OR for clinical pregnancy = 1.38, 95 % CI 0.55-3.46).

Based on the results of this pilot study, EI in the luteal phase of the cycle preceding the frozen embryo transfer cycle does not appear to significantly improve implantation or clinical pregnancy rates.