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ICSI – What Is It, Do We Need It, and Is It Safe?

By Francis Polansky, M.D.

Intracytoplasmic sperm injection (ICSI) was introduced in 1992 to improve fertilization in couples with male factor infertility undergoing In Vitro Fertilization treatment (IVF).

How does ICSI work?

In traditional IVF, most eggs will fertilize when they are placed in a culture dish with several thousand normal sperm. This process is called “in vitro fertilization”.

Before a sperm can fertilize an egg, the head of the sperm has to attach to the outside of the egg. Then it pushes through the outer layer of the egg (zona pellucida) to the inside of the egg. Sometimes the sperm cannot penetrate the zona layer. Intracytoplasmic Sperm Injection can be used to help fertilize the egg. ICSI involves the direct injection of a single sperm into the interior of an egg using an extremely thin glass needle.

ICSI allows couples with male factor infertility to achieve fertilization and live birth rates similar to those achieved with the in vitro fertilization method in men with normal sperm counts. ICSI can be performed even in men with no sperm in the ejaculate if sperm can be successfully aspirated from the testis.

Why would we need ICSI?

ICSI helps to overcome a man’s fertility problems, for instance:

  • He may produce too few sperm
  • His sperm may be not be shaped correctly or move in a normal fashion
  • The sperm may have trouble attaching to the egg
  • A blockage in his reproductive tract may keep sperm from getting out


ICSI can also be used if in a previous In Vitro Fertilization Treatment, the traditional in vitro fertilization method has not produced fertilization.

Will ICSI work?

ICSI typically fertilizes 50% to 80% of eggs. But the following may occur after the use of ICSI:

  • The ICSI procedure might damage some eggs
  • The eggs might not grow into embryos even after they are injected with sperm
  • The embryos may stop developing


Once fertilization takes place, a patient’s chance of giving birth is the same as if she had IVF with traditional in vitro insemination.

Can ICSI affect a baby’s development?

If a woman conceives spontaneously, there is a 1.5% to 3% chance that the baby will have a major birth defect. In studies of male factor infertility, ICSI has been associated with a small increased risk of adverse outcomes in offspring. Whether this association is due to the ICSI procedure itself or to inherent sperm defects has not been determined. Recent studies have not detected any differences in the intellectual and motor development of children born after ICSI, conventional IVF, or spontaneous conception.

Certain genetic abnormalities have been shown to increase in ICSI offspring. The prevalence of sex chromosome (X and Y) abnormalities in children conceived via ICSI is higher than observed in the general IVF population, but the difference between the two groups is very small (0.8% to 1.0% in ICSI offspring vs. 0.2% in the general IVF population). Translocations (a re-arrangement of chromosomes that can cause miscarriage) may be more common in ICSI offspring (0.36%) than in the general population (0.07%).

These risks are generally attributed to the underlying male factor cause of infertility rather than resulting from the ICSI procedure itself. Men with abnormal semen analyses are more likely themselves to have chromosome abnormalities and may produce sperm with abnormal chromosomes. These abnormalities could be passed to their offspring.

In conclusion, the ICSI procedure has been an extensively used method of fertilizing eggs in In Vitro Fertilization allowing men who in the past were unable to father children to have genetic offspring. It is likely that the ICSI procedure itself does not increase the risk of genetic abnormalities.

January 2015

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