The sequential use of IVF disposable devices doesn’t cause cumulative toxicity unless a defective device compromises the entire procedure

This study investigated whether the sequential use of disposable devices in routine IVF procedures induces cumulative embryotoxicity. Ten combinations, each including 7 to 25 disposables covering essential IVF steps-sperm collection, oocyte retrieval, fertilization, embryo culture, transfer, and freezing/thawing-were tested using the Mouse Embryo Assay (MEA) in triplicate. A defined volume of culture medium was employed to extract potential toxic compounds from device associations. Both extracts and controls underwent MEA. Fresh zygotes were cultured for 120 h at 37.3 °C in a tri-gas incubator. Embryo development was monitored morphologically at E1.5, E4.0, and E5.0. At E5.0, blastocysts were fixed and analyzed for total cell counts. Of the ten tested combinations, two (20%) demonstrated toxicity, evidenced by reduced blastocyst formation and lower cell numbers at E5.0. Toxicity was attributed to specific consumables-sperm straws and embryo transfer catheters-rather than cumulative effects. Although previously certified as non-toxic, these devices were found harmful both individually and in combination. Variability in MEA protocols may explain inconsistencies in manufacturer assessments. The study concludes that sequential disposable use does not inherently cause cumulative toxicity unless a defective device intervenes, emphasizing the need for standardized preclinical MEA testing to ensure embryo safety and optimize IVF outcomes.