There is no evidence that intracytoplasmic morphologically selected sperm injection (IMSI) provides subfertile patients an additional benefit over the standard intracytoplasmic sperm injection (ICSI) in terms of live birth or miscarriage rates, concluded an intervention review and meta-analysis conducted by the Cochrane Menstrual Disorders and Subfertility Group.1
ICSI, which is a sperm micromanipulation technique, is a useful tool for subfertile couples who have difficulty conceiving because of a reduced sperm concentration or slow sperm motility in the male partner. In ICSI, sperm are injected directly into an egg. A newer technique, called IMSI, is a sperm selection method that uses ultra high-powered (6000x) magnification to identify the most motile sperm.
Although initial studies have shown that IMSI is associated with a higher pregnancy rate in couples who have experienced repeated implantation failures, the researchers found no significant difference between IMSI and ICSI for live birth reported by the one study of low-quality evidence in which live birth was evaluated (risk ratio, 1.14). What this means clinically is that for women with a 38% chance of live birth with regular ICSI, the chance of live birth with IMSI ranges between 30% and 63%, explained the researchers.1
IMSI was associated with a significant improvement in clinical pregnancy rate (RR, 1.29), but the researchers considered this very low quality evidence because of imprecision, an inconsistent observed effect across studies, and a high risk of publication bias. Statistically, women with a 33% chance of achieving pregnancy with regular ICSI had a 36% to 52% chance of achieving pregnancy with IMSI, the researchers explained.
The difference in rate of miscarriage between IMSI and ICSI was not significant (RR, 0.82), but this result also was based on very low quality evidence. According to the researchers, for pregnant women with a 22% risk of miscarriage using ICSI, the risk using IMSI would be 13% to 25%. There is no evidence that the use of IMSI increases congenital abnormalities, but none of the studies included in this intervention review and meta-analysis reported their occurrence.
Based on the available evidence from randomized controlled trials, the clinical use of IMSI is not supported. Before IMSI can be recommended in clinical practice, high-quality studies are needed.
- IMSI offers no benefit over ICSI for live birth or miscarriage rates.
- Although there is evidence that IMSI improves clinical pregnancy rates, the evidence is of very low quality.
1. Teixeira DM, Barbosa MAP, Ferriani RA, et al. Regular (ICSI) versus ultra-high magnification (IMSI) sperm selection for assisted reproduction. Cochrane Database Syst Rev. 2013;7:CD010167. DOI: 10.1002/14651858.CD010167.pub2.