The Effect of Different Flushing Media Used to Aspirate Follicles on the Outcome of a Commercial Ovum Pickup-ICSI Program in Mares.
Authors: Cuervo-Arango Juan, Claes Anthony N, Beitsma Mabel, Stout Tom A E
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Flushing Media Selection in Equine OPU-ICSI Programmes The choice of follicle flushing medium during ovum pickup significantly impacts embryo production outcomes in equine ICSI programmes, with implications for breeding practitioners relying on assisted reproductive technologies. Researchers compared two commercial embryo flushing media (EFM1 and EFM2, both heparin-supplemented) against a medium specifically formulated for oocyte collection across 234 Warmblood mares, measuring blastocyst developmental rates and embryo yield per OPU-ICSI session. Oocytes collected with EFM1 yielded substantially lower blastocyst rates (11.9%) and fewer viable embryos per session (0.88) compared with the dedicated oocyte flushing medium (19.2% and 1.24 respectively), whilst EFM2 performance was comparable to the specialist medium. The inferior results with EFM1 were attributed to benzyl alcohol preservatives present in the heparin formulation, a component known to compromise oocyte membrane integrity during the brief exposure period (<1.5 hours) required for collection. For veterinarians and breeding programmes operating OPU-ICSI services, this work underscores the importance of scrutinising flushing medium composition—particularly preservative content in heparin sources—as seemingly minor formulation differences can meaningfully reduce embryo recovery rates and programme efficiency.
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Practical Takeaways
- •Use oocyte-specific flushing media (OFM) rather than general embryo flushing media (EFM) to improve blastocyst production rates in commercial OPU-ICSI programs
- •Verify that heparin used in collection media is preservative-free; benzyl alcohol in multidose heparin vials compromises oocyte viability and developmental competence
- •Selection of appropriate flushing media components directly impacts embryo production efficiency and should be carefully evaluated when establishing or troubleshooting OPU-ICSI protocols
Key Findings
- •OPU-ICSI using EFM1 resulted in significantly lower blastocyst rate (11.9%) compared to OFM (19.2%, P < .05)
- •Blastocysts per OPU-ICSI session were lower with EFM1 (0.88 ± 1.3) versus OFM (1.24 ± 1.2)
- •EFM1 heparin containing benzyl alcohol preservative negatively affected oocyte developmental competence compared to preservative-free EFM2
- •Oocyte exposure to inappropriate flushing media for less than 1.5 hours significantly reduced commercial OPU-ICSI program outcomes