Washington, Jan 16 (IANS) Men rendered sterile by aggressive cancer therapy may still be able to father children, says a new study.

Paul Turek, former professor at the University of California-San Francisco and founder of the Turek Clinic, who led the study, pioneered the technique, called Fine Needle Aspiration (FNA) sperm mapping, that is able to discover pockets of viable sperm in the testes.

The sperm can then be extracted with minimally invasive procedures and used for in-vitro fertilisation and single sperm injection.

'This advance in medicine has been a long time in the making, but we have reached a point where a critical mass of physicians believe in and are using sperm mapping as a state-of-the-art tool to help couples conceive,' said Turek.

The study documented cases of men who had received high doses of chemotherapy and bone marrow transplantation. They had previously been diagnosed and treated for haematologic (blood) cancers and later, as survivors, desired to father children.

The men were initially found to have no sperm in their ejaculate, a condition known as azoospermia, a finding that occurs in more than 70 percent of cancer survivors after bone marrow transplantation, says a Turek Clinic release.

After undergoing the testis sperm mapping technique, small pockets of sperm were discovered. With assisted reproduction using these sperm, they successfully fathered healthy children.

The findings were published in Bone Marrow Transplantation.