In the past 20 years, reproductive medicine has made remarkable advancements, especially with the introduction of second-generation IVF (ICSI) technology for treating male infertility. Along with surgical techniques for sperm extraction from the epididymis and testicles, these breakthroughs have fundamentally changed the reproductive prospects of men with severe sperm abnormalities, fertilization issues, ejaculation disorders, or irreversible obstructive azoospermia. Men with these serious infertility problems, who cannot be helped by other methods or surgeries, now have the opportunity to become fathers.

The second-generation IVF technique is medically known as “Intracytoplasmic Sperm Injection” (ICSI). This technique involves injecting a single sperm directly into the cytoplasm of an egg cell under a microscope, facilitating passive fertilization. This results in the formation of a fertilized egg, which is then used for embryo transfer to achieve pregnancy. ICSI is currently a crucial method for treating male infertility, with a fertilization success rate of over 70%. However, since ICSI is invasive for the embryo, it is only used when necessary.

When Is ICSI Recommended?

  • Extremely low sperm count or poor sperm motility.
  • High percentage of abnormal sperm or only a small number of healthy sperm.
  • Irreversible obstructive azoospermia: Using sperm extracted from the testicles or epididymis via surgery.
  • Failure of fertilization using conventional IVF (i.e., fertilization not achieved with first-generation IVF).

Tips: Increasing evidence suggests that for couples who do not meet the above criteria, using conventional fertilization (IVF) instead of ICSI actually results in higher success rates. ICSI can be performed with either fresh or thawed frozen sperm. The embryologist selects the best-quality sperm based on shape, size, and motility for fertilization. The process of ICSI is identical to a conventional IVF cycle, except that a forced fertilization method is used on the day of egg retrieval.

How Does It Work?

Step 1: Sperm Selection
The healthiest sperm cells typically have a specific shape and size, with an oval head and a long tail that propels them forward during swimming. Since infertility issues often arise from a shortage of such healthy sperm, careful selection of sperm for ICSI is crucial. Additionally, sperm motility is important, referring to its ability to swim and penetrate the egg cell, which depends on the length and structure of its tail. Curled or double-tailed sperm have reduced swimming efficiency.
In ICSI, a small sample of prepared sperm is placed in a viscous medium to slow their movement, allowing the best sperm to be chosen based on shape, motility, and swimming pattern. The most “normal”-looking and active sperm are then selected. The sperm is immobilized by gently squeezing its tail with a glass needle and then aspirated from the tail into the needle, ready for injection.
For patients with low sperm count or poor motility, the embryologist may spend hours searching for the ideal sperm for ICSI. Rest assured, we make every effort to find the perfect sperm.

Step 2: Fertilization
The egg cell is placed on a special dish under a microscope, using a highly precise micromanipulation system. The mature egg is carefully held in place, while a fine glass micro-needle loaded with a single sperm is used to pierce the zona pellucida (the egg’s outer layer), penetrate the cell membrane, and deliver the sperm into the cytoplasm.
In other words, second-generation IVF technology involves the embryologist performing many tasks on behalf of the sperm: it does not need to swim, compete, or penetrate the egg cell. Its only task is to create the “spark” of fertilization with the egg.

Embryo Culture
The fertilized egg is then placed in an incubator, and on the second day, it is examined for signs of fertilization.

Tips: ICSI is more invasive than conventional IVF and requires more handling, which increases the risk of damaging the egg cell. However, the likelihood of damage due to the procedure is very low, less than 2%. Experienced technicians and embryologists undergo rigorous ICSI training, which significantly enhances the success rate of fertilization.