Ectopic pregnancy rates in frozen versus fresh embryo transfer in in vitro fertilization: A systematic review and meta-analysis

The rising incidence of heterotopic pregnancy: Current perspectives and associations with in-vitro fertilization

Heterotopic pregnancy is the simultaneous occurrence of an intrauterine and ectopic pregnancy. This study aims to review the current literature regarding heterotopic pregnancy with a focus on its diagnosis and associations with in-vitro fertilization (IVF). Studies have shown that ovarian hyperstimulation syndrome and multiple embryo transfer during IVF are associated with an increased risk of heterotopic pregnancy. Tubal abnormalities such as pelvic inflammatory disease and previous tubal or abdomino-pelvic surgery have also been identified as risk factors. Diagnosis is challenging as the falsely reassuring presence of an intrauterine fetus frequently delays early intervention. Treatment should be individualised, but is often prompt surgical intervention, and focuses on terminating the ectopic pregnancy while minimizing harm to the mother and intrauterine fetus.

Fresh versus frozen embryo transfer after an in vitro fertilization cycle: Is there a difference in the ectopic pregnancy rate?

Background

Ectopic pregnancy (EP) occurring because of an abnormal site of embryo implantation is a major cause of maternal morbidity and mortality if not timely diagnosed and intervened. To avert the increase in the rates of EP through in vitro fertilization cycles as compared to spontaneous conception, fertility experts have resorted to multiple measures, of which the most studied is shifting to frozen embryo transfer (ET) in place of fresh transfer. The aim of this study was to evaluate the difference in the risk of ectopic implantation in women undergoing fresh versus frozen-thawed ETs.

Methods

It was a retrospective single-center cohort study wherein 802 of the 853 patients who underwent ET during the study period were analyzed. These patients were further subdivided into fresh transfer group (n = 339) and frozen transfer group (n = 443). The primary outcome measure was to study the difference in EP rates in the two groups and the secondary outcome measure was to analyze the clinico-therapeutic profile of the two subgroups of EPs.

Results

Of the 802 women who underwent ETs, 19 women had an ectopic implantation with an overall incidence of 2.3%. Among the 19 EPs, there were eight EPs (2.23%) in the fresh transfer group and 11 EPs (2.48%) in the frozen transfer group, but the difference was not statistically significant (P > 0.05). The clinico-therapeutic profile of the patients was comparable in both the groups.

Conclusion

Frozen ET cycle does not mandatorily reduce the incidence of EP in spite of the maintenance of the intrauterine milieu compared to a stimulated cycle. Larger and more robust studies are needed for recommending frozen ET cycle as a preventive modality for EP.