Immediate post-denudation intracytoplasmic sperm injection is associated with higher fertilization and early cleavage-stage embryo yield: a prospective sibling-oocyte cohort from Libyan ICSI cycles.

Intracytoplasmic sperm injection (ICSI) has become an integral practice in assisted reproduction technology (ART), but the optimal time interval between oocyte denudation (DN) and ICSI is still not well defined. Libya remains underrepresented in global fertility estimates, and prospective paired data on DN-to-ICSI timing from Libyan IVF practice are limited. We aimed to investigate whether performing ICSI immediately after DN, compared with an intended four-hour delay, affects pregnancy outcomes and early embryology yield. This prospective cohort study was conducted at the Fertility and Reproductive Medicine Center, Beirut Hospital, Benghazi and included 88 Libyan ICSI cycles. After enzymatic-mechanical DN using hyaluronidase, mature metaphase II (MII) oocytes were injected with selected sperm. Within each cycle, sibling MII oocytes were allocated in a 1:1 ratio to immediate ICSI or delayed ICSI after an intended interval of about four hours, using a computer-generated within-cycle allocation sequence. For clinical comparison, cycles were allocated by pre-generated permuted-block randomization to transfer blastocysts under one timing condition (44 cycles/arm). The primary outcome was normal fertilization (two pronuclei); secondary outcomes included cleavage (Day 3), blastulation and blastocyst quality (Day 5/6; Gardner-Schoolcraft), biochemical pregnancy and clinical pregnancy. Immediate DN-ICSI was significantly associated with higher fertilization rates than delayed injection (80.07% ± 17.09% vs 70.80% ± 17.37%; mean difference: 9.26, 95% CI 4.40-14.12; p = 0.0003) and a higher cleavage rate (76.89% ± 17.03% vs 67.97% ± 18.47%; mean difference 8.93 points, 95% CI 3.59-14.26; p = 0.0013). Biochemical pregnancy (40.9% vs 54.5%; p = 0.200) and clinical pregnancy (29.5% vs 27.3%; p = 0.813) did not differ significantly. These results suggest that a shorter DN-to-ICSI interval may improve fertilization and early embryo development, with no observed differences in blastulation or early pregnancy outcomes. Larger multicenter studies with cumulative live births are required to determine clinical relevance.Intracytoplasmic sperm injection (ICSI) has become an integral practice in assisted reproduction technology (ART), but the optimal time interval between oocyte denudation (DN) and ICSI is still not well defined. Libya remains underrepresented in global fertility estimates, and prospective paired data on DN-to-ICSI timing from Libyan IVF practice are limited. We aimed to investigate whether performing ICSI immediately after DN, compared with an intended four-hour delay, affects pregnancy outcomes and early embryology yield. This prospective cohort study was conducted at the Fertility and Reproductive Medicine Center, Beirut Hospital, Benghazi and included 88 Libyan ICSI cycles. After enzymatic-mechanical DN using hyaluronidase, mature metaphase II (MII) oocytes were injected with selected sperm. Within each cycle, sibling MII oocytes were allocated in a 1:1 ratio to immediate ICSI or delayed ICSI after an intended interval of about four hours, using a computer-generated within-cycle allocation sequence. For clinical comparison, cycles were allocated by pre-generated permuted-block randomization to transfer blastocysts under one timing condition (44 cycles/arm). The primary outcome was normal fertilization (two pronuclei); secondary outcomes included cleavage (Day 3), blastulation and blastocyst quality (Day 5/6; Gardner-Schoolcraft), biochemical pregnancy and clinical pregnancy. Immediate DN-ICSI was significantly associated with higher fertilization rates than delayed injection (80.07% ± 17.09% vs 70.80% ± 17.37%; mean difference: 9.26, 95% CI 4.40-14.12; p = 0.0003) and a higher cleavage rate (76.89% ± 17.03% vs 67.97% ± 18.47%; mean difference 8.93 points, 95% CI 3.59-14.26; p = 0.0013). Biochemical pregnancy (40.9% vs 54.5%; p = 0.200) and clinical pregnancy (29.5% vs 27.3%; p = 0.813) did not differ significantly. These results suggest that a shorter DN-to-ICSI interval may improve fertilization and early embryo development, with no observed differences in blastulation or early pregnancy outcomes. Larger multicenter studies with cumulative live births are required to determine clinical relevance.Intracytoplasmic sperm injection (ICSI) has become an integral practice in assisted reproduction technology (ART), but the optimal time interval between oocyte denudation (DN) and ICSI is still not well defined. Libya remains underrepresented in global fertility estimates, and prospective paired data on DN-to-ICSI timing from Libyan IVF practice are limited. We aimed to investigate whether performing ICSI immediately after DN, compared with an intended four-hour delay, affects pregnancy outcomes and early embryology yield. This prospective cohort study was conducted at the Fertility and Reproductive Medicine Center, Beirut Hospital, Benghazi and included 88 Libyan ICSI cycles. After enzymatic-mechanical DN using hyaluronidase, mature metaphase II (MII) oocytes were injected with selected sperm. Within each cycle, sibling MII oocytes were allocated in a 1:1 ratio to immediate ICSI or delayed ICSI after an intended interval of about four hours, using a computer-generated within-cycle allocation sequence. For clinical comparison, cycles were allocated by pre-generated permuted-block randomization to transfer blastocysts under one timing condition (44 cycles/arm). The primary outcome was normal fertilization (two pronuclei); secondary outcomes included cleavage (Day 3), blastulation and blastocyst quality (Day 5/6; Gardner-Schoolcraft), biochemical pregnancy and clinical pregnancy. Immediate DN-ICSI was significantly associated with higher fertilization rates than delayed injection (80.07% ± 17.09% vs 70.80% ± 17.37%; mean difference: 9.26, 95% CI 4.40-14.12; p = 0.0003) and a higher cleavage rate (76.89% ± 17.03% vs 67.97% ± 18.47%; mean difference 8.93 points, 95% CI 3.59-14.26; p = 0.0013). Biochemical pregnancy (40.9% vs 54.5%; p = 0.200) and clinical pregnancy (29.5% vs 27.3%; p = 0.813) did not differ significantly. These results suggest that a shorter DN-to-ICSI interval may improve fertilization and early embryo development, with no observed differences in blastulation or early pregnancy outcomes. Larger multicenter studies with cumulative live births are required to determine clinical relevance.