Brazilian Study Reports Similar Outcomes with ICSI and IMSI

Intracytoplasmic morphologically selected sperm injection (IMSI), a modification of ICSI procedure, evaluates motile sperm organellar morphology by magnifying the sample >6000 times with a high power microscope, enhanced by digital imaging. Several studies have demonstrated that IMSI, compared to ICSI, improves treatment outcomes, including the rate of implantation, pregnancy, and live birth. Now, a Brazilian research team reports similar outcomes, in terms of fertilization rate, embryo cleavage rate, and day 2 embryo quality, with both the conventional and modified ICSI procedures. However, the scientists did not rule out the possibility of IMSI positively influencing the late paternal effects. The study results have been published online in the European Journal of Obstetrics & Gynecology and Reproductive Biology.

Ana L Mauri and colleagues from the Centre for Human Reproduction, Sao Paulo, Brazil, noted the day 2 embryo quality to investigate the impact of IMSI on early paternal effects in 30 couples, who fulfilled atleast one of the following parameters:
• Minimum of 2 previous implantation failures or miscarriages following IVF/ICSI
• Male factor infertility

The researchers randomly allocated the sibling oocytes of each participant to either ICSI or IMSI. An inverted microscope, consisting of Nomarski differential interference contrast optics, Uplan Apo 100x oil/1.35 objective lens, and variable zoom lens, which magnify the sample 8,400 times, was used to select spermatozoa in the IMSI group. In contrast, sperm selection was performed at 400x magnification in the conventional ICSI group. The criteria for assessing top quality embryo were the presence of 4 identical blastomeres on day 2, without any fragments or multinucleation.

Of the 331 metaphase II oocytes selected, IMSI was carried out in 159, while the remaining were injected by ICSI (n=172). In the IMSI group, only the morphologically normal sperm, as detected at high magnification, were used. The findings did not show much variation with respect to the following parameters between the two subsets.

Parameters (%) ICSI IMSI
Fertilization rate 70.9 70.4
Early embryo cleavage rate 66.9 60.4
Cleavage rate 99.2 99.1
Proportion of top quality embryos 57.8 52.2

On the contrary, an earlier prospective randomized trial by Antinori et al (Reproductive BioMedicine Online, 2008) demonstrated the benefits of performing IMSI as opposed to conventional ICSI in patients with severe oligoasthenoteratozoospermia. After selecting the sperm at 6600x magnification, the findings showed a higher clinical pregnancy rate compared to ICSI. Also, IMSI was found to be most effective in those patients who had ≥2 previous failed attempts, especially with respect to the rates of pregnancy and miscarriage.

Several techniques of selecting superior sperm (based on morphology) have been proposed as sperm morphology is considered vital for diagnosing male fertility-related problems and predicting outcomes of fertilization and pregnancy. Some of such innovative techniques include swim-up and density gradient centrifugation, magnetic-activated cell sorting (MACS), electrophoretic separation of spermatozoa, and high magnification ICSI (IMSI).

Although IMSI has several potential advantages as indicated in many studies, Antinori et al, in their 2008 research, emphasized on the need for addressing some practical difficulties before recommending IMSI as a routine IVF technique, especially for patients with complicated male infertility. The factors which limit the widespread use of the modified ICSI procedure are enumerated below:
• Needs standardization of the procedure
• Requires specialized equipment to obtain the high magnification and useful criteria
• Necessitates trained, experienced, and highly qualified embryologists
• More time for proper sperm selection.

References

1. Mauri AL, Petersen CG, Oliveira JB, Massaro FC, Baruffi RL, Jr JG. Comparison of day 2 embryo quality after conventional ICSI versus intracytoplasmic morphologically selected sperm injection (IMSI) using sibling oocytes. Eur J Obstet Gynecol Reprod Biol. 2010 May;150(1):42-6.

2. Antinori M, Licata E, Dani G, et al. Intracytoplasmic morphologically selected sperm injection: a prospective randomized trial. Reprod Biomed Online. 2008 Jun;16(6):835-41.

3. Moskovtsev SI. Management of patients with high sperm DNA damage. Indian J Med Res. 2008 Feb;127(2):101-3.

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