Both ICSI (intracytoplasmic sperm injection) and IVF(in-vitro fertilisation) are both assisted reproductive treatment (ART) procedures in which eggs are fertilised outside the body.

The main differences are:

ICSI: In ICSI, a single healthy sperm is selected and injected directly into a mature egg using a thin glass needle. This bypasses any barriers that may prevent natural sperm-egg interaction and facilitates fertilisation.

IVF: In IVF, eggs and sperm are combined in a laboratory dish, and fertilisation occurs naturally, as the sperm swim to the eggs and penetrate the eggs to fertilise them. 

Some common indications for ICSI in these cases include:

Male factor infertility:  If the male partner has low sperm count, poor sperm motility, or abnormal sperm morphology, ICSI can be used to directly inject sperm into the egg, increasing the chances of successful fertilisation.

Previous IVF failures: Couples or individuals who have experienced multiple failed IVF cycles or fertilisation difficulties in previous attempts may benefit from ICSI as a more targeted approach to achieve fertilisation.

Absence or blockage of sperm ducts: If a partner has obstructive azoospermia, where the sperm ducts are blocked or absent, sperm can be retrieved through testicular or epididymal aspiration and used for ICSI to fertilise eggs.

Ejaculation issues: Those facing ejaculation problems, such as retrograde ejaculation or anejaculation, may benefit from ICSI to achieve fertilisation using their own eggs or donor eggs.

Use of frozen sperm: Those using frozen sperm samples, which may have lower motility compared to fresh sperm, can benefit from ICSI to improve the chances of successful fertilisation when using their own eggs or donor eggs.