Intracytoplasmic Sperm Injection (ICSI)

ICSI at a glance

• If a man’s sperm cannot penetrate the outer layer of the egg due to problems with the sperm, intracytoplasmic sperm injection can be used to inject a single sperm into an egg to enable fertilization.
• ICSI is used with IVF to fertilize an egg, creating an embryo that can then be implanted one to five days later.
• ICSI fertilizes 50 to 80 percent of eggs, and birth defects caused by ICSI are rare.

How ICSI works

In order for a man’s sperm to fertilize a woman’s egg, the head of the sperm must first attach to the outside of the egg, then push through the outer layer of the egg to the inside of the egg (the cytoplasm). If the sperm cannot penetrate the outer layer, a procedure called intracytoplasmic sperm injection (ICSI) can inject the sperm directly into the egg to aid fertilization.

In traditional in vitro fertilization (IVF), the sperm are mixed in a laboratory dish with the woman’s egg to produce fertilization. With ICSI, however, a single sperm is injected into the center of the egg to ensure the initial stage of fertilization occurs. Once fertilized, the embryo (fertilized egg) grows in a laboratory for one to five days, and then is placed in the woman’s uterus (womb).

When to use ICSI

ICSI helps overcome several male fertility problems:

• The man may produce too few sperm.
• The sperm may not be shaped correctly or move in a normal fashion.
• The sperm may have trouble attaching to the egg.
• A blockage in the reproductive tract may keep sperm from getting out.
• Unexplained infertility (ICSI can be used when traditional IVF has not produced fertilization, regardless of the apparent condition of the sperm).

ICSI success

ICSI fertilizes 50 to 80 percent of eggs, according to the American Society for Reproductive Medicine. However, the following may occur after the use of ICSI:

• The procedure might damage the egg.
• The egg might not grow into an embryo, even after a sperm is injected.
• The embryo may stop growing.

Once fertilization takes place, a couple’s chance of giving birth to a single baby, twins, or triplets is the same as IVF without ICSI.

Affects of ICSI on a baby’s development

There is a 1.5 percent to 3 percent chance that a baby conceived naturally will have a major birth defect, according to the American Society for Reproductive Medicine. Chances of birth defects after ICSI are rare, but certain conditions that have been associated with the use of ICSI (Beckwith-Wiedemann syndrome, Angelman syndrome, hypospadias, or sex chromosome abnormalities) are thought to occur in far less than 1 percent of children conceived using this technique, according to the American Society for Reproductive Medicine. These, though, may not be linked to ICSI, but possibly to the IVF process in general. In addition, some of the problems that cause infertility may be genetic, so some men who would not have had children without ICSI, father children that may inherit the infertility gene. Therefore, boys conceived with the use of ICSI may also have infertility issues as adults.