In some cases of male infertility, sperm retrieval may be performed with a procedure known as microsurgical epididymal sperm aspiration (MESA). Most often, MESA is performed on men who suffer from congenital abnormalities of the vas deferens and in those who have had a vasectomy. It is also performed on patients diagnosed with vas deferens obstructions caused by trauma or medical conditions. Any spermatozoa recovered during sperm retrieval can be used immediately in an in vitro fertilization (IVF) procedure or stored for later use with cryopreservation.
Mature sperm are stored within the tubules of the epididymis, a coiled tube located behind the testes. In normally functioning fertile males, the spermatozoa travel from the epididymis through the tubes of the vas deferens to the urethra, where the sperm enter the ejaculate fluid.
Sperm Retrieval Procedure
MESA may be performed in a hospital or in a clinic equipped with an operating room. Generally, the procedure is performed under local anesthesia, using a special sperm cord-blocking anesthetic. Patients may also require sedation.
The surgeon makes an incision through the scrotal tissue, exposing the tunic vaginalis that covers the testes. Another small incision is made through the tunic to reveal the epididymis. Using a high-powered surgical microscope, the surgeon gently separates the tissues to select a tubule within the epididymis. A special syringe fitted with a micro-puncture instrument and pipette is used to pierce the tubule. If the tubule is clearly visible through the tunic, an incision in the tunic may not be necessary.
A small amount of fluid is aspirated from the tubule and immediately prepared for evaluation. Fluid is applied to a slide with a drop of solution and a specialist examines the sample to determine if any viable sperm are present. If quantities of sperm are detected, the surgeon will aspirate additional fluid for an IVF procedure or cryopreservation. Cryopreservation is recommended for any additional sperm not used during an IVF procedure, because there is a risk that the female partner will not become pregnant on the initial visit.
If sufficient numbers of sperm are not found within the tubule, the surgeon will make additional micro-punctures in adjoining tubules, in an effort to find a sufficient quantity of viable spermatozoa. In the event the surgeon is unable to aspirate fluid containing sperm from the tubules, he or she may elect to aspirate fluid from the nearby efferent ductiles.
Once the sperm retrieval has been completed, the micro-punctures are closed with fine monofilament nylon sutures, while the tunica vaginalis and scrotal tissue are usually closed with thicker sutures to prevent water and contaminants from entering the site.
Post Operative Recovery
There may be some initial swelling, redness and bruising at the site following surgery. Patients may also be required to wear a scrotal support for 24 hours. Dressings are usually removed in three to four days. Discomfort and pain is usually relieved with over-the-counter pain medication. Full recovery is usually achieved in about two weeks, but some patients may experience discomfort for several weeks.
MESA Risks and Complications
MESA is less invasive than most sperm retrieval techniques; however, there is a chance of inflammation, infection and bleeding. In rare cases, patients may develop epididymal fibrosis or epididymal injury.