Impact of retained embryos on the outcome of assisted reproductive technologies

Objective: To assess the impact of embryo retention in the embryo transfer catheter followed by "immediate" retransfer on pregnancy outcome in women undergoing assisted reproduction. Design: Retrospective analysis of embryo transfer following in vitro fertilization. Setting: Assisted reproductive technology practice in a university in vitro fertilization program. Patient(s): In vitro fertilization charts for 1,812 embryo transfer cycles representing 1,139 patients between January 1997 and March 2002 were reviewed. Intervention(s): None. Main Outcome Measure(s): Pregnancy rate, implantation rate, delivery rate. Result(s): Three embryo transfer cycles were excluded from analysis because of missing data, leaving 1,364 embryo transfers during oocyte recovery cycles and 445 embryo transfer cycles using thawed embryos. Seventy-one embryo transfers (3.9% of all transfers) were complicated by finding retained embryos after the initial embryo transfer-all retained embryos were immediately retransferred. There was no difference in the frequency of retained embryos during oocyte retrieval versus thawed embryo cycles. The pregnancy, implantation, and delivery rates per embryo transfer were not negatively affected by embryo(s) retained in the transfer catheter. Age, fresh versus frozen embryo, use of ultrasound during the procedure, or transferring physician did not influence pregnancy outcome. Conclusion(s): Immediate retransfer of embryos retained in the catheter following the initial transfer attempt did not have an adverse effect on pregnancy outcome.