IMSI is a technique similar to conventional ICSI, however it allows a more accurate visualization of the sperm. Through a high-resolution optical system coupled to the microscope, this technique differs by the principle of sperm selection to inject into the oocyte (egg) at an increase greater than 6,300 times. On the other hand, ICSI offers a 400-fold increase, making it impossible to observe vacuoles and other sperm malformations.

With an increase in IMSI, visualization of the vacuoles present, mainly of the sperm head, and a better evaluation of sperm morphology (head, intermediate part and tail) is allowed. These vacuoles are harmful because they cause lesions in the sperm chromatin, poor mitochondrial function and higher rates of aneuploidies, thus interfering in the integrity of the already formed embryo and leading to lower rates of pregnancy, higher rates of abortions and transmission of genetic alterations to the embryo.

His first success report was in 2003 and several studies have analyzed the efficiency of using IMSI in association with conventional ICSI. Scientific studies since 2003 show that pregnancy results with this new technique are around 60%, a significant increase, compared to 30-45% of conventional ICSI. However, patients who benefit from this technology are those who have: severe male factor; embryonic implantation failures; low embryonic quality and increased percentage of sperm DNA fragmentation.