The effect of air bubble position after blastocyst transfer on pregnancy rates in IVF cycles

Abstract

OBJECTIVE: Studies examining the relationship of air bubble position to IVF cycle outcome have focused primarily on Day 3 embryo transfer, with little data existing on the optimal location for blastocyst transfer (BT). Therefore, the objective of this study was to investigate the relationship between air bubble position after BT and pregnancy rates (PR).DESIGN: Retrospective cohort study.MATERIALS AND METHODS: All non-donor BTs by a single provider at a University center were analyzed from January 2006 through March 2008. All transfers were performed with the Tefcat catheter (Cook IVF), loaded via the “three drop procedure,” with air bubbles separating the drop of medium containing the embryos from two drops of culture media before and after the embryo drop. The distance from the air bubble to the fundus, as seen on abdominal ultrasound, was measured at the time of transfer, and later categorized as <10 mm, 10-20 mm, and >20 mm. Clinical pregnancy was defined as gestational sac with or without cardiac activity. Logistic regression was used to analyze the impact of air bubble position on PR, adjusting for the potential confounders of age, parity and FSH, using Stata v. 8.2.Table 1Clinical Pregnancy RateNPregnancy RateORP-value95% CI<10 mm2462.5%–––10-20 mm17642.4%0.700.07∗0.4468-1.033>20 mm11538.3%0.350.02∗0.109-0.842∗As compared to <10mm, adjusted for age, parity and FSH. Open table in a new tab CONCLUSIONS: This study is the first to suggest that BT closer to the fundus is associated with higher PR. Because BT occurs close to the time of implantation, one would expect less embryo migration. Although no ectopic pregnancies occurred in our study when ET was <10 mm from the top, this outcome should be closely monitored in larger studies. OBJECTIVE: Studies examining the relationship of air bubble position to IVF cycle outcome have focused primarily on Day 3 embryo transfer, with little data existing on the optimal location for blastocyst transfer (BT). Therefore, the objective of this study was to investigate the relationship between air bubble position after BT and pregnancy rates (PR). DESIGN: Retrospective cohort study. MATERIALS AND METHODS: All non-donor BTs by a single provider at a University center were analyzed from January 2006 through March 2008. All transfers were performed with the Tefcat catheter (Cook IVF), loaded via the “three drop procedure,” with air bubbles separating the drop of medium containing the embryos from two drops of culture media before and after the embryo drop. The distance from the air bubble to the fundus, as seen on abdominal ultrasound, was measured at the time of transfer, and later categorized as <10 mm, 10-20 mm, and >20 mm. Clinical pregnancy was defined as gestational sac with or without cardiac activity. Logistic regression was used to analyze the impact of air bubble position on PR, adjusting for the potential confounders of age, parity and FSH, using Stata v. 8.2. ∗As compared to <10mm, adjusted for age, parity and FSH. CONCLUSIONS: This study is the first to suggest that BT closer to the fundus is associated with higher PR. Because BT occurs close to the time of implantation, one would expect less embryo migration. Although no ectopic pregnancies occurred in our study when ET was <10 mm from the top, this outcome should be closely monitored in larger studies.