Minimized microbial contamination rate in conventional IVF cycles after modifications of cumulus-oocyte complex...

Could the microbial contamination rate of oocytes and embryos in conventional IVF cycles be further reduced by modifying the handling procedures of cumulus-oocyte complexes (COC)?

Two modifications were applied to COC handling procedures. First, a mark was made on the outer wall of the 10-cm Petri dish to indicate the site from which the follicular fluid was poured out during the oocyte retrieval process (modified handling 1) since May 2018. Second, a modified way of pipetting during denuding (modified handling 2) has been adopted since June 2019. The microbial contamination rates before and after each modification were compared. The clinic outcomes of patients with a history or at a high risk of microbial contamination were reported after incorporating the two modifications of COC handling.

After the first modification was implemented, the contamination rate was remarkably reduced from 0.37% (9/2436) to 0.18% (2/1089). After adding the second modification, no new contamination occurred in the subsequent 3178 conventional IVF cycles (P = 0.001). Moreover, no contamination was noted in patients with a history of microbial contamination or persistent candidal vaginitis during conventional IVF after modifications of COC handling.

Modifying the handling procedures of COC can minimize the microbial contamination rate in conventional IVF cycles. Contamination risk directly derived from the urogenital tracts might be less likely than what we thought to be with current IVF techniques.