When to do intracytoplasmic sperm injection: a prospective comparison

The purpose of the study was to assess the fertilization rate and embryo development in sibling human oocytes after split insemination in patients with and without isolated teratozoospermia.

A prospective cohort study at a university affiliated reproduction center was performed. Hundred and three patients during the time periods 01-2013 to 12-2015 had split insemination ordered for their first IVF cycle. The primary outcome measured was fertilization rate. Secondary outcomes were the number and quality of embryos.

Mature oocytes at the time of collection were assigned as follows: 558 to IVF and 556 to ICSI. An additional 48 immature oocytes matured while awaiting spontaneous fertilization with IVF for a total of 606 in that group. The study group of normal strict sperm morphology ≤ 4 included 61 patients, and the control group included 42 patients with normal strict sperm morphology > 4. ICSI was statistically favored over IVF only in cases with normal strict sperm morphology ≤ 4%. There was a higher fertilization rate in ICSI compared to IVF (74.4% vs. 38%, p < 0.0001), a higher number of day 2 (4 ± 3.4 vs. 2.4 ± 2.7, p < 0.0001), day 3 (4 ± 3.4 vs. 2.2 ± 2.7, p < 0.0001) and day 5 embryos (2.2 ± 2.6 vs. 1.2 ± 2, p = 0.001), and they were of better quality; however, it did not reach significance (p = 0.062). A similar advantage for ICSI was seen in a subgroup of unexplained infertility with normal strict sperm morphology > 4%.

In conclusion, in couples with normal strict sperm morphology ≤ 4%, there is an advantage of ICSI over IVF in terms of fertilization rate, quantity and quality of cleavage stage embryos and blastocysts. Based on the results, ICSI seems reasonable as a first-line treatment in patients with normal strict sperm morphology ≤ 4%, as well as in patients with unexplained infertility.