Surgical sperm retrieval is a treatment option for men who are experiencing infertility and not able have baby with their partner. It could be due to obstruction preventing sperm release, due to some injury or infection.
Another reason could be due to congenital absence of the vas deferens. It could be due to Vasectomy. Non-obstructive azoospermia - the testicles are producing such low numbers of sperm that they don't reach the vas.