Percutaneous epididymal sperm aspiration (PESA) is a technique used to determine sperm counts in the event of a possible blockage of the vas deferens

Vas deferens

The vas deferens , also called ductus deferens, , is part of the male anatomy of many vertebrates; they transport sperm from the epididymis in anticipation of ejaculation....

. A small needle is inserted through the skin of the scrotum to collect sperm from the epididymis

Epididymis

The epididymis is part of the male reproductive system and is present in all male amniotes. It is a narrow, tightly-coiled tube connecting the efferent ducts from the rear of each testicle to its vas deferens. A similar, but probably non-homologous, structure is found in cartilaginous...

, where sperm are usually stored after production in the testes. It can also be used to extract sperm for intracytoplasmic sperm injection

Intracytoplasmic sperm injection

Intracytoplasmic sperm injection is an in vitro fertilization procedure in which a single sperm is injected directly into an egg.-Indications:...

(ICSI).