Testicular sperm aspiration; this involves placing a needle attached to a syringe through the skin of the scrotum and simply sucking out the fluid inside the testicle.
Microsurgical epididymal sperm aspiration; is an open surgical sperm retrieval procedure that uses an operating microscopy to locate the tubules of the epididymis precisely, so that large numbers of sperm can be extracted.
Some small studies have been done to compare success rates after the different types of surgical sperm retrieval. These concluded that MESA gives the highest number of sperm, with a hundred times more sperm being recovered compared to TESA and perch biopsy. MESA also produced sperm that were better swimmers and therefore more useful for infertility treatments, including IVF and ICSI.