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Updated: May 19, 2026
Minimally Invasive Embryo Transfer and Embryo Vitrification at the Optimal Embryo Stage in Rabbit Model
Published on: May 16, 2019
Frozen-thawed embryo transfer is associated with a significantly reduced incidence of ectopic pregnancy
Bruce S Shapiro1, Said T Daneshmand, Laura De Leon
1Fertility Center of Las Vegas, Las Vegas, Nevada 89117, USA. bsshapiro@aol.com
Objective:
To compare the incidence of ectopic pregnancy (EP) after fresh ET and thawed ET.
Design:
Retrospective cohort study.
Setting:
Private fertility center.
Patient(S):
This retrospective study included 2,150 blastocyst transfers, including all 1,460 fresh autologous blastocyst transfers and all 690 transfers of autologous blastocysts derived from post-thaw extended culture of thawed bipronuclear oocytes in the 8-year study period 2004-2011.
Intervention(S):
None.
Main Outcome Measure(S):
Visualized EP and treated persistent pregnancy of unknown location.
Result(S):
The rate of visualized EP was 1.5% in pregnancies in fresh autologous cycles, which was significantly more than the rate of 0 with autologous post-thaw extended culture. The rates of treated persistent pregnancy of unknown location were 2.5% and 0.3% in these two groups, respectively, a difference that was also statistically significant (relative risk 7.3, 95% confidence interval 1.7-31.0).
Conclusion(S):
Relative to fresh transfer, thawed ET was associated with significantly reduced incidence of EP. These findings are consistent with ovarian stimulation increasing the risk of EP.
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