Intracytoplasmic sperm injection (ICSI) versus high insemination concentration (HIC) for human conception in vitro.

The use of high insemination concentration (HIC) for in vitro fertilization (IVF) was compared with intracytoplasmic sperm injection (ICSI) in cases of male factor infertility. Sibling oocytes (n = 252) from 24 patients were used, 123 for HIC and 129 for ICSI. Although the incidence of fertilization was decreased with HIC (48% v. 61%), this treatment was nevertheless a viable option for many patients, especially when ICSI was not available. However, there was a higher incidence of cytoplasmic fragmentation of embryos after HIC compared with ICSI (36% v. 10%, P = 0.003) and the outcome was significantly affected by the severity of teratozoospermia. Using a cut-off of 5% normal forms, the incidence of fertilization with HIC for the group with < 5% normal forms was 37% compared with 72% for the group with > 5% normal forms; there was also a significant decrease in cleavage rate (P = 0.05) and the number of regular embryos (P = 0.005), and an increase in cytoplasmic fragmentation (P = 0.006) in patients with < 5% normal forms. No distinction was made between cases of teratozoospermia when ICSI was used. The present study confirms the value of HIC as a first line treatment for male infertility, as long as ICSI remains significantly more expensive and concerns on safety are mooted. However, the use of sibling oocytes for ICSI is recommended, especially in cases with < 5% normal sperm morphology.