Effects of embryo retention during embryo transfer on IVF outcomes

Embryo retention and live birth in frozen embryo transfer cycles: a cohort study

OBJECTIVE

To study the effect of embryo retention in the transfer catheter on pregnancy outcomes in frozen embryo transfer (FET) cycles.

DESIGN

Retrospective cohort study.

SETTING

Tertiary-care academic medical center.

PATIENT(S)

This retrospective study involved a total of 39,118 women who underwent FET cycles at a tertiary-care academic medical from January 2016 to December 2022.

INTERVENTION(S)

Women were divided into a control group (n = 38,933) and embryo retention group (n = 185). The women in the embryo retention group had been propensity scores matched with those in the control group at a 1:4 ratio.

MAIN OUTCOME MEASURE(S)

The primary outcome was live birth (LB). The secondary outcomes were biochemical pregnancy, clinical pregnancy (CP), miscarriage, and ectopic pregnancy.

RESULT(S)

The overall incidence of embryo retention in the transfer catheter was 0.47% (185/39,118). The pregnancy outcome in the embryo retention group after propensity score matching (PSM) was comparable to that before PSM, with a reduced likelihood of biochemical pregnancy (odds ratio [OR], 0.83; 95% confidence interval [CI], 0.72-0.95), CP (OR, 0.81; 95% CI, 0.69-0.96), and LB (OR, 0.80; 95% CI, 0.66-0.97). In addition, the birth weight in the embryo retention group was higher compared with the control group. However, no differences were observed in terms of miscarriage, ectopic pregnancy, cesarean delivery, as well as gestational age both before and after PSM.

CONCLUSION(S)

Embryo retention in the transfer catheter decreases the chance of biochemical pregnancy, CP, and LB in FET cycles.

Observations on clinical assessment of endometrial receptivity

This brief review will examine the investigation of the endometrial cavity before embryo transfer using various techniques, including hysteroscopy, endometrial biopsy using immunohistochemistry and molecular microarray, and ultrasound imaging. All these investigative tools are presently subject to controversy and require large prospective controlled trials for validation. During embryo transfer, the occurrence of a retained embryo does not appear to have a negative impact on pregnancy outcome, and finally, consistent data indicate that physical activity immediately after embryo transfer has no impact on pregnancy outcome.