IMSI stands for Intracytoplasmic Morphologically Selected Sperm Injection. Using high magnification light microscopy on a live, motile sperm sample, the most morphologically normal sperm is selected from the sperm population and then used for intracytoplasmic sperm injection (ICSI). The goal of IMSI is to select the "best sperm" to be injected into the egg with the thought that this sperm will have the highest possibility of success in IVF.
The IMSI method is based on motile sperm organellar morphology examination (MSOME). The examination of motile sperm is performed in real time using an inverted light microscope equipped with high-power Nomarski optics enhanced by digital imaging to achieve a magnification in excess of 6000x. This allows the sperm to be examined in greater detail, including the nucleus which contains the sperm’s genetic material. Some studies suggest that using this technique selects better quality sperm and results in higher pregnancy rates and lower miscarriage rates compared to conventional ICSI.
The Hamilton Thorne IMSI-Strict software aids in the IMSI process by measuring the size and shape of the sperm head, detecting midpiece abnormalities and identifying vacuoles on the live sperm sample. The results are displayed in real-time to assist the embryologist in selection of sperm to use for ICSI.
The Hamilton Thorne IMSI-Strict software is unique in combining MSOME and Kruger Strict criteria in one analysis.