Clinical Outcomes of Rescue Intracytoplasmic Sperm Injection at Different Timings Following In Vitro Fertilization

en 34987986 Clinical Outcomes of Rescue Intracytoplasmic Sperm Injection at Different Timings Following In Vitro Fertilization Background: Although rescue intracytoplasmic sperm injection (r-ICSI) is extensively used worldwide, the indication of r-ICSI and its optimal timing remains obscure. This study aimed to assess the outcomes of r-ICSI following in vitro fertilization in different timings when fertilization is confirmed. Methods: This study included 5,156 cycles (47,785 eggs). Fertilization was confirmed by polar body analysis after 4 and 6 hr of coincubation of the sperm and oocyte. Oocytes that underwent IVF were divided into two groups based on the time when a second polar body was detected in more than 30% of all oocytes (Four-hr group and six-hr group). If the second polar body was not detected or was present in less than 30% of all oocytes after six hr of coincubation, rescue-ICSI (r-ICSI) was performed for oocytes without a second polar body (r-ICSI group). Results: The fertilization rates of two pronuclear (2PN) oocytes in the three groups (Four-hr group, six-hr group, and r-ICSI group) were 70.7%, 51.3%, and 58.0%, respectively. The blastocyst formation rates were 62.8%, 53.4%, and 42.9%, respectively. Conclusion: Performing r-ICSI after six hr of coincubation can salvage cases with fertilization failure in IVF. The higher fertilization rate of r-ICSI indicates that all oocytes without signs of fertilization after six hr of coincubation should undergo r-ICSI. Assisted reproductive techniques, Fertilization failure, In vitro fertilization, Infertility, Intracytoplasmic sperm injection 251 258 https://www.jri.ir/article/120137 /documents/fullpaper/en/120137.pdf YukiShiraiwaHanabusa Women’s Clinic, Hyogo, Japan112304NoritoshiEnatsuHanabusa Women’s Clinic, Hyogo, Japanenatsunoritoshi@hanabusaclinic.com112305KazukiYamagamiHanabusa Women’s Clinic, Hyogo, Japan112306KoyuFuruhashiHanabusa Women’s Clinic, Hyogo, Japan112307ToshirohIwasakiHanabusa Women’s Clinic, Hyogo, Japan112308JunkoOtsukiOkayama University Assisted Reproduction Technology Center, Okayama, Japan112309MasahideShiotaniHanabusa Women’s Clinic, Hyogo, Japan112310