Intracytoplasmic sperm injection (ICSI)

In cases of male fertility problems, IVF cannot be offered as a treatment option. ICSI is the method of choice, even in cases of severe oligoasthenoteratozoospermia.

Only a single sperm is required for every mature oocyte.

ICSI involves injecting a spermatozoon into the cytoplasm of a mature oocyte using micromanipulation devices (microscope and micromanipulators). Considering that the human oocyte has a size of 1/10 of millimeter, and that a spermatozoon is 100 times smaller, ICSI is an extremely sensitive procedure and can be performed successfully only by experienced embryologists, with perfect technical skills.

ICSI is also performed after testicular biopsy in cases of azoospermia.

You can read more on ICSI:

What is ICSI and indications
How is ICSI performed
ICSI and safety issues