Temperature fluctuations during embryo transfer can be mitigated by optimizing transfer protocol.

Research Question: What impact do variations in embryo transfer catheter loading and movement procedures have on temperature and pH fluctuations during embryo transfer?

Design: Mock embryo transfers were conducted to test the impact of air flow/movement, use of catheter coverings, and the type of workstation used for catheter loading on catheter temperature. A thermocouple probe inserted into the tip of the outer catheter or taped to the exterior of the inner catheter recorded temperature within the catheter every 5 s from time of mock embryo loading (T) to 60 s (T + 60 s) or from the start of transit (T). Fluctuations in culture medium pH in embryo transfer dishes were monitored.

Results: The rate of cooling during transit was faster (all P < 0.05) when catheters were uncovered compared with all covering methods tested. This resulted in a lower catheter temperature at T + 20 s (28.43 ± 0.30 °C) compared with catheters covered by plastic tubing (31.4 ± 0.30 °C), paper (31.0 ± 0.26 °C) or paper + thumb (31.1 ± 0.78 °C; all P ≤ 0.05). Temperature was maintained more effectively when catheters were loaded in a crib compared with a heated stage, until initiation of transit, when the rate of temperature decrease was similar. Culture medium pH increased more rapidly when embryo transfer dishes remained on a heated stage during the procedure compared with in an open crib.

Conclusions: Temperature loss during the embryo transfer procedure can be mitigated by reducing the transit time and using catheter coverings. Use of a crib for catheter loading only improved temperature stability while the catheter remained in the crib, not during transit, and reduced pH fluctuations during the procedure.