Intracytoplasmic Sperm Injection (ICSI), developed in 1991, is an advanced fertilization technique used in assisted reproduction. It involves selecting a single sperm, based on mobility and morphology, and directly injecting it into the egg. Before injection, the egg is stripped of its protective granulosa cells, allowing for precise sperm placement.  

ICSI is particularly beneficial for severe male infertility, as it requires only a few viable sperm to create embryos, even when sperm count is extremely low.  

Why Is ICSI Used for Preimplantation Genetic Testing (PGT)?  

ICSI is the standard fertilization method when preimplantation genetic testing (PGT) is performed. This is because:  

• Only one sperm fertilizes the egg, eliminating the risk of contaminating the embryo’s genetic analysis with DNA from multiple sperm.  

• During embryo biopsy, this ensures that only embryonic cells are tested, preventing misinterpretation of genetic results.  

Why Isn’t ICSI Used for All Cases of Infertility?  

ICSI is primarily reserved for:  

• Severe male infertility  

• Previous IVF fertilization failure  

• Cases requiring preimplantation genetic testing (PGT)  

For other infertility cases, conventional IVF offers similar success rates, making ICSI unnecessary as a routine procedure.