What is IMSI?
IMSI (Intracytoplasmic Morphologically Selected Sperm Injection) is a variation of the standard ICSI technique aimed at optimizing sperm selection. It involves the use of a high-powered microscope with enhanced contrast, allowing embryologists to examine sperm at magnifications up to 1500x—far greater than standard ICSI. This detailed view enables the selection of sperm with optimal shape and structure, particularly focusing on head morphology and the presence of vacuoles, which can impact embryo quality and development.
How is sperm visualized in IMSI?
IMSI uses an imaging system called Differential Interference Contrast (DIC) microscopy, which relies on polarizers and optical filters to produce high-contrast images. A glass-bottomed dish is also used to ensure maximum clarity. Together, these elements provide a high-resolution, three-dimensional view of the sperm, allowing embryologists to assess fine structural details.
What sperm structures can IMSI reveal?
IMSI technology enables the detailed observation of sperm structures that may not be visible under standard ICSI magnification. One key feature it reveals is the presence of vacuoles—small, fluid-filled bubbles within the sperm head. These vacuoles are believed to be linked to DNA damage and can vary in size and number. Research has shown that sperm with two or more small vacuoles or a single large vacuole are associated with poorer outcomes, such as reduced blastocyst development, when used in microinjection procedures¹.
Who may benefit from IMSI?
IMSI is especially recommended in the following situations:
- Infertility issues in the male partner: Associated with poor sperm quality or DNA fragmentation.
- Failed IVF attempts: It is recommended for couples who have experienced poor embryo development or aneuploid embryos in previous IVF cycles.
- Recurrent miscarriage or implantation failure: Couples experiencing these issues may also benefit from IMSI.
¹ Khaif, M. Y., et al. (2022). Impact of sperm DNA fragmentation on blastocyst formation and pregnancy rates. Obstetrics and Gynecology International, 13(1), 32–38.
