Compared to ICSI cycles, conventional insemination cycles have a much higher rate of embryo contamination by microorganisms. Could the microbial contamination rate of oocytes/embryos be further reduced in conventional IVF cycles by modifying the handling procedures of cumulus-oocyte complexes (COC)?
Two modifications were applied to COC handling procedures. Firstly a mark has been made on the outer wall of the 10 cm Petri dish to indicate the site from which the follicle fluid was poured out during the oocyte pick-up process (modified handling 1) since May 2018. Secondly, a modified way of pipetting during denuding (modified handling 2) has been adopted since Jun 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 the adoption of the two modifications of COC handling.
After adopting only the first modification, 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.
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Tao Li received her PhD's degree in Reproductive Medicine from Sun Yat-sen University in 2003. She is a senior clinical embryologist and IVF laboratory director at the IVF Center of the Third Affiliated Hospital of Sun Yat-sen University. She has conducted research projects on embryonic stem cells, in vitro fertilization and infertility.
Accepted: March 2, 2023
Received in revised form: February 21, 2023
Received: October 20, 2022
Publication stageIn Press Journal Pre-Proof
© 2023 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.