IMSI is a variation of ICSI that uses a high power light microscope (enhanced by digital imaging) to magnify the sperm sample over 6000 times. Sperms are then selected which have the most normally-shaped nuclei and least number of vacuoles. . The sperm is then injected into the egg and then placed in the incubator for further development.
The technique for examining sperm to use in IMSI was developed by a team led by Professor Bartoov. In 2002, his team used a high-powered microscope to determine which morphological characteristics of sperm might affect the outcome of ICSI. They suggested that ICSI pregnancy rates may be affected by subtle abnormalities in the shape of the sperm nucleus which embryologists may not detect during normal ICSI sperm selection.
In 2003, the same group published a study that looked at whether selecting sperm using IMSI improves the pregnancy rate in couples with repeated ICSI failures (compared to conventional ICSI).
Comparing results of ICSI with IMSI the pregnancy rate was significantly higher (60% vs 25%) and the miscarriage rate significantly lower (14% vs 40%) in the IMSI group compared to the conventional ICSI group.
There also is a significant improvement in implantation, pregnancy and birth rates using IMSI in patients with two or more previously unsuccessful IVF-ICSI attempts.
The pregnancy rates for patients were 29.8% in the IMSI group compared with 12.9% in the ICSI group. The miscarriage rates for these patients were also significantly lower in the IMSI group compared with the ICSI group
The use of IMSI is limited by the resources needed to carry out the technique. IMSI takes a minimum of 60 minutes and more often takes several hours. In addition the technique involves special equipment to reach the necessary magnification ( X6000), it has to be carried out by experienced embryologists trained in the specific technique, and this explains the significant extra cost of providing IMSI.
IVF-IMSI/IVF-ICSI are very good options for-
- Tubal blockage or severe tubal damage
- Ovarian failure (NO PERIODS),
- Severe male factor infertility (less than 5 million/hpf)
- Advanced stages of endometriosis
- In women over 40 years old
- In couples with a long duration of infertility (over 5 years)