Men with infertility issues can often have little to no motile sperm present in their ejaculate and can experience blockages that prevent sperm from reaching the epididymis. In these cases, a mesa tesa (PESA or TESA) can be performed to obtain sperm from the testicle or the epididymis and can be used in conjunction with other fertility treatments for successful fertilization.

During MESA, the patient under local anesthesia has a small incision in the scrotum and then a needle is passed into the epididymis where sperm is aspirated and drawn up. A scrotal support is then placed to prevent edema in the scrotum after the procedure. Occasionally a man may not have enough sperm obtained by MESA and will need to be evaluated with a testicular aspiration known as TESE.

MESA is a minimally invasive alternative to percutaneous epididymal sperm aspiration (PESA) which requires a blindly passed needle into the epididymus. PESA can lead to a scrotal wound infection and hematoma. MESA also has a slight risk of damage to the epididymal tissue with each attempt.

MESA, as well as a more advanced technique called micro-TESE, can be used to obtain high quality sperm for In-Vitro Fertilization and Intracytoplasmic Sperm Injection (ICSI) with very good fertilization and pregnancy rates. Arizona Center for Fertility Studies recommends that any sperm that is not utilized in an IVF/ICSI cycle be cryopreserved to avoid having to perform another MESA or TESA.mesa tesa