IMSI (Intracytoplasmic Morphologically Selected Sperm Injection) is an advanced variation of the standard ICSI technique, aimed at optimizing sperm selection. It utilizes a high-powered microscope equipped with an enhanced contrast system, allowing for sperm examination at magnifications of up to 900x—much higher than standard ICSI. This advanced magnification helps to identify sperm with the most favourable morphology, focusing on characteristics such as head shape and the presence of vacuoles, which can affect embryo development.
How is sperm visualized?
The IMSI technique uses Differential Interference Contrast (DIC) system which employs polarizers and filters for optical adjustments. It also requires a glass-bottomed dish for maximum clarity. DIC improves the visibility of transparent sperm structures, providing a high-resolution, three-dimensional view.
What are sperm structures that are now observable?
This technology allows the detection of vacuoles (fluid-filled bubbles) in sperm heads, which are not visible with a standard ICSI microscope. These vacuoles, thought to result from DNA damage, can vary in number and size. The presence of two or more small vacuoles or one large vacuole in sperm is associated with reduced blastocyst development, when used for microinjection.
IMSI is particularly beneficial in the following situations:
- Infertility issues in the male partner: Especially if there is poor sperm health 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 miscarriages or implantation failure: Couples facing these challenges may also benefit from IMSI.
When applied to the right patient population, IMSI offer advantages over standard ICSI, including increased implantation and pregnancy rates.
