Embryo quality after sperm selection using density gradient centrifugation or microfluidic technology: a sibling oocyte study.

This sibling oocyte study was designed to determine how embryo quality is influenced after sperm selection using microfluidic sperm sorting (MSS) technology compared to a standard density gradient centrifugation (DGC). A single-centre prospective non-inferiority sibling oocyte study was performed between October 2023 and February 2024, comparing DGC to MSS. Primary endpoint was embryo utilisation rate. Only ICSI cycles with ejaculated sperm and at least 6 mature oocytes (MII) were included. Sample-size calculation indicated a number of 253 MII for each arm. Each raw semen sample was split in two fractions processed by DGC and by MSS using Zymot 850µl® device. During ICSI, half of the MII were injected with sperm processed by DGC and the other half by MSS. The inseminated oocytes were individually cultured in cleavage/blastocyst medium (Origio) for maximum 7 days. The mean female age was 34.5±4.4 years and partner age was 37.5±5.5 years. Sperm concentration (x106/ml) was similar following DGC (2.9±1.2) or MSS (3.5±5.0) (p=0.16). Progressive motility (% A+B) was significantly lower following DGC vs MSS (74.0%±17.2 vs 89.9%±10.4 (p<0.01), respectively. The DFI of the raw semen samples was 5.6%±3.6. A number of 51 ICSI-cycles were included with 658 cumulus-oocyte-complexes retrieved of which 532 MII were randomized to either DGC (n= 265) or MSS (n=267) groups. Fertilisation rate was not significantly different between DGC and MSS (208/265, 78.5% vs 209/267, 78.3%, respectively; p=0.96). Similarly, good embryo quality on day 3 (159/208, 76.4% vs 161/209, 77.0%, respectively; p=0.97) and good blastocyst quality (≥Bl3BB) (86/208, 41.3% vs 76/209, 36.4%, respectively; p=0.30) were not different between the two groups. Utilisation rates (number of transferred and cryopreserved embryos) were similar between the two groups: both per MII (104/265, 39.2% vs 107/267, 40.1%, respectively; p=0.91) and per fertilised oocyte (104/208, 50.0% vs 107/209, 51.2%, respectively; p=0.88) in DGC vs MSS. Since fertilisation, embryo quality and utilisation rate are similar in both groups, the use of Zymot 850µl® device offers the advantage of eliminating the negative effects and time-consuming nature of centrifugation. Another advantage is that scheduling of semen samples can be planned more efficiently. [ABSTRACT FROM AUTHOR]