Microsurgical epididymal sperm aspiration. An open surgical sperm retrieval procedure that uses an operating microscopy to extract sperm directly from the tubules of the epididymis, the sperm storage area in the testis.

Microscopic epididymal sperm aspiration (extraction), which is normally shortened to MESA, is a technique for collecting sperm. It involves using a surgical microscope to open the small tubes within a patient’s epididymis (a long, coiled tube that stores and transports sperm from the testes). Once these are open, the specialist will look for sperm cells to retrieve. 

The sperm cells collected from this will then most often be used as part of an intracytoplasmic sperm injection-assisted in-vitro fertilisation (ICSI IVF) procedure. This refers to taking the sperm directly from a male patient and injecting them into individual eggs in a laboratory environment. The hope from this is that the sperm cells will fertilise these individual eggs, resulting in the creation of embryos that can be implanted in the womb of the female partner, or a chosen surrogate. From this step, it is possible that they may go on to achieve a successful pregnancy.

The technique has been noted to work well for patients who are producing adequate numbers of sperm but these cells are being blocked from travelling through the testicle to be ejaculated. There are many reasons this may be happening in the body, and therefore many reasons the procedure may be required. These reasons include:

  • The patient has had a prior vasectomy
  • The patient has had a prior hernia repair with mesh
  • There is a blockage of the seminal vesicles (seminal glands; tubular glands that lie behind the bladder and make fluid that helps to make up semen)
  • The patient has epididymal blockage

An operating microscope and specialist skills are needed to be able to identify the tubes that are most likely to contain sperm. Any samples collected are also immediately examined in order to look for sperm cells. 

Most doctors carrying out this procedure suggest that collecting sperm from the epididymis yields better results and ensures that better quality sperm is retrieved. This is because sperm that has been stored in the epididymis has had more time to mature. 

When the procedure is carried out, the patient will have to be put under a general or spinal anaesthetic. The operation will require an incision in the scrotum to gain access to one or both testicles. Any sperm cells that are then retrieved can be used right away or frozen for use at another time. 

In cases where no sperm cells are found, it will be necessary to look inside the testicle for viable sperm. This is achieved through another procedure, called testicular sperm extraction, or TESE.