Regular (ICSI) versus ultra-high magnification (IMSI) sperm selection for assisted reproduction

Background: sperm micromanipulation, such as intracytoplasmic sperm injection (ICSI), is very useful for treating couples in which the male partner has a reduced sperm concentration or motility, or both. Recently, a new method of sperm selection named 'motile sperm organelle morphology examination' (MSOME) has been described, which analyses sperm under ultra-high powered (6000x) magnification. Initial studies have shown that intracytoplasmic morphologically selected sperm injection (IMSI), using spermatozoa selected under high magnification, is associated with higher pregnancy rates in couples with repeated implantation failures.

Search date: we searched the medical literature in May 2013 for studies that evaluated the effectiveness and safety of using ultra-high magnification (over 6000x) for sperm selection prior to ICSI, compared with the use of a conventional ICSI procedure, with a 200-400x magnification.

Study characteristics: we found nine randomised controlled trials, evaluating 2014 couples, that had compared regular ICSI with IMSI for assisted reproduction. These studies were funded by fertility centres and universities.

Key results and quality of the evidence: for live birth, there was low-quality evidence compatible with either benefit or harm: for women with a 38% chance of achieving live birth using regular ICSI, the chance of achieving live birth using ultra-high magnification (IMSI) would be between 30% and 63%. For clinical pregnancy, there was very-low-quality evidence compatible with benefit: for women with a 33% chance of achieving pregnancy using regular ICSI, the chance of achieving pregnancy using IMSI would be between 36% and 52%; the quality of this evidence was downgraded because of imprecision, inconsistency of the observed effect across studies, and high risk of publication bias. For miscarriage, there was very-low-quality evidence compatible with either benefit or harm: for pregnant women with an 22% risk of miscarriage using regular ICSI, the risk using IMSI would be between 13% and 25%. There was no evidence concerning congenital abnormalities. We concluded that the current evidence does not support using IMSI: there is no evidence of benefit for live birth and miscarriage, we are very uncertain of the beneficial effect of IMSI in clinical pregnancy, and there is no evidence of the effect of this intervention on congenital abnormalities. More studies to improve the evidence quality are necessary before recommending IMSI in clinical practice.

Authors' conclusions: 

Results from RCTs do not support the clinical use of IMSI. There is no evidence of effect on live birth or miscarriage and the evidence that IMSI improves clinical pregnancy is of very low quality. There is no indication that IMSI increases congenital abnormalities. Further trials are necessary to improve the evidence quality before recommending IMSI in clinical practice.

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Background: 

Subfertility is a condition found in up to 15% of couples of reproductive age. Gamete micromanipulation, such as intracytoplasmic sperm injection (ICSI), is very useful for treating couples with compromised sperm parameters. Recently a new method of sperm selection named 'motile sperm organelle morphology examination' (MSOME) has been described and the spermatozoa selected under high magnification (over 6000x) used for ICSI. This new technique, named intracytoplasmic morphologically selected sperm injection (IMSI), has a theoretical potential to improve reproductive outcomes among couples undergoing assisted reproduction techniques (ART).

Objectives: 

To compare the effectiveness and safety of IMSI and ICSI in couples undergoing ART.

Search strategy: 

We searched for randomised controlled trials (RCT) in electronic databases (Cochrane Menstrual Disorders and Subfertility Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS), trials registers (ClinicalTrials.gov, Current Controlled Trials, World Health Organization International Clinical Trials Registry Platform), conference abstracts (ISI Web of knowledge), and grey literature (OpenGrey); in addition, we handsearched the reference lists of included studies and similar reviews. We performed the last electronic search on 8 May 2013.

Selection criteria: 

We considered only truly randomised controlled trials comparing ICSI and IMSI to be eligible; we did not include quasi or pseudo-randomised trials. We included studies that permitted the inclusion of the same participant more than once (cross-over or 'per cycle' trials) only if data regarding the first treatment of each participant were available.

Data collection and analysis: 

Two review authors independently performed study selection, data extraction, and assessment of the risk of bias and we solved disagreements by consulting a third review author. We corresponded with study investigators in order to resolve any queries, as required.

Main results: 

The search retrieved 294 records; from those, nine parallel design studies were included, comprising 2014 couples (IMSI = 1002; ICSI = 1012). Live birth was evaluated by only one trial and there was no significant evidence of a difference between IMSI and ICSI (risk ratio (RR) 1.14, 95% confidence interval (CI) 0.79 to 1.64, 1 RCT, 168 women, I2 = not applicable, low-quality evidence). IMSI was associated with a significant improvement in clinical pregnancy rate (RR 1.29, 95% CI 1.07 to 1.56, 9 RCTs, 2014 women, I2 = 57%, very-low-quality evidence). We downgraded the quality of this evidence because of imprecision, inconsistency, and strong indication of publication bias. We found no significant difference in miscarriage rate between IMSI and ICSI (RR 0.82, 95% CI 0.59 to 1.14, 6 RCTs, 552 clinical pregnancies, I2 = 17%, very-low-quality evidence). None of the included studies reported congenital abnormalities.

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