Endometrial Scratch (Injury): Does Timing Matter?

Objective: To examine the timing of endometrial scratch in a patient's menstrual cycle and whether there is an association with subsequent implantation. Materials and methods: This study is a retrospective chart review on women, aged 18-45, seen in a reproductive endocrine clinic seeking conception. Timing of endometrial scratch was defined as proliferative (cycle day 1-9), periovulatory (CD11-16), or secretory (CD19+). All periovulatory biopsies were performed at time of oocyte retrieval in women freezing all oocytes/embryos for future use. Primary outcome of interest was positive beta-hCG within ninety days of the endometrial scratch. Results: Sixty-nine cases of endometrial scratch met the inclusion criteria. There were no statistically significant differences in baseline demographic characteristics between those who received endometrial injury in the three phases. There was no significant difference in frequency of positive beta-hCG within 90 days of endometrial scratch between the patients who received an endometrial scratch in the three phases (proliferative 65.6%, periovulatory 69.6%, secretory 64.3%; p = 0.9332). Conclusion: In contrast to prior studies which showed up to 65% decrease in implantation rate after endometrial scratch performed at time of oocyte retrieval, this study shows no significant difference in implantation when the injury is performed at the time of oocyte retrieval as compared to other phases of the menstrual cycle. Possible explanation may be that we did not perform a scratch if fresh embryo transfer was planned. As endometrial injury is associated with patient discomfort, performing the scratch while under conscious sedation for oocyte retrieval may be desirable in cycles where fresh embryo transfer is not planned. Future studies are needed to assess the validity of these findings.