40w LaterGuide

When sperm count, motility, or other sperm characteristics are significantly impaired, fertilization may be more difficult. Assisted reproductive techniques have been developed to help overcome some of these male fertility factors.

Two techniques you may hear about are ICSI (intracytoplasmic sperm injection) and IMSI (intracytoplasmic morphologically selected sperm injection).

1) ICSI: Intracytoplasmic Sperm Injection

ICSI is a technique used during in vitro fertilization (IVF). After an egg is retrieved and prepared in the laboratory, an embryologist selects a single sperm and injects it directly into the cytoplasm of the egg using a very fine needle.

Because only one sperm is needed for each mature egg, ICSI can be particularly useful when sperm numbers are very low, sperm motility is poor, or surgically retrieved sperm are being used.

ICSI may also be considered when there has been poor or failed fertilization with conventional IVF in a previous treatment cycle.

However, ICSI is not automatically better than conventional IVF for everyone. In couples without a clear male fertility factor, routine ICSI has not been shown to consistently improve live-birth rates.

When might ICSI be considered?

ICSI may be considered in situations such as:

severe abnormalities in sperm count or motility
azoospermia when sperm have been surgically retrieved from the testis or epididymis
ejaculation disorders where sperm need to be obtained by special methods
previous poor or failed fertilization with conventional IVF
certain treatments where direct injection of sperm into the egg is clinically necessary

The decision is based on the overall semen findings, previous treatment history, the condition of the eggs, and other fertility factors.

2) IMSI: High-Magnification Sperm Selection

With conventional ICSI, embryologists select sperm based mainly on movement and appearance under a laboratory microscope.

IMSI is a variation of ICSI in which sperm are examined at much higher magnification before one is selected for injection into the egg. The aim is to identify sperm with fewer visible structural abnormalities.

However, selecting a sperm that looks more normal under high magnification does not guarantee that its DNA or chromosomes are normal.

Is IMSI better than ICSI?

Not necessarily.

Research has investigated whether IMSI can improve pregnancy or live-birth rates compared with conventional ICSI. So far, the evidence is uncertain, and routine use of IMSI has not been clearly shown to improve live-birth rates or reduce miscarriage rates.

For this reason, IMSI is not a standard requirement for everyone undergoing ICSI. Some fertility clinics may consider it in selected situations based on previous treatment results, sperm characteristics, and laboratory protocols.

In summary

1. ICSI involves injecting a single sperm directly into an egg and is especially useful for significant male-factor infertility.
2. ICSI can also be considered after previous poor or failed fertilization with conventional IVF.
3. IMSI adds high-magnification sperm selection before ICSI.
4. IMSI is not proven to be superior to conventional ICSI for all patients and should be considered selectively.