Techniques for Sperm Harvesting
Modern reproductive technology has evolved tremendously to help men who were previously considered to be incapable of fathering children. The ability to fertilize eggs by directly injecting sperm into an egg (intra-cytoplasmic sperm injection) means that very few sperm are needed to achieve a successful pregnancy. Sperm is produced in the testicle and transported to the penis where fluid from the prostate combines with the sperm to produce semen.
Sperm retrieval procedures are necessary in situations where there is no sperm in a man’s ejaculate. This condition can result from blockage of the ejaculatory system (obstructive azoospermia) or from a failure of sperm production in the testicle (non-obstructive azoospermia). The most common cause of obstructive azoospermia is a prior vasectomy but other causes include prior infection, prior hernia repair with mesh or other prior surgery on the testicles. Non-obstructive azoospermia can be due to genetic conditions, prior testicle infections or hormone abnormalities. These conditions can interrupt the production of normal sperm within the testicle. Fortunately, even in these instances, there are often areas of normal sperm production.
The ideal technique for harvesting sperm depends on a variety of factors. Sperm can be retrieved using an open surgical approach, or through the skin using a needle. Each approach has certain risks and benefits and each may not be appropriate for everyone. Although it is sometimes possible to harvest enough sperm for intrauterine insemination (IUI), where the sperm is inserted directly into the woman’s uterus, it is more common to use harvested sperm for in-vitro fertilization (IVF). The sperm that is retrieved can be used immediately to fertilize an egg or can be frozen for use at a later time.
PESA (Percutaneous Epididymal Sperm Extraction)
PESA and TESA are similar procedures where a needle is used to extract sperm from the testicle or epididymis. The epididymis is an organ that lives behind the testicle and is the location where sperm mature and develop the ability to move. The epididymis can be enlarged after a vasectomy or in other conditions where there is a blockage. Both of these procedures can often be performed with only mild sedation and local anesthetic. A needle is inserted into the testicle or epididymis and an attempt is made to collect sperm. The sample collected is immediately examined under a microscope to look for healthy appearing sperm. These sperm can be used immediately to fertilize an egg or can be frozen for use at a later time.
These techniques can be used as a first line approach for sperm collection. Both PESA and TESA and most effective when trying to collect sperm in a man who has undergone a vasectomy and the epididymis is enlarged. The benefits of this approach are that they are relatively painless and do not require an incision in the scrotum or a general anesthetic. The risks of the procedure include bleeding, damage to the epididymis and not being able to obtain sufficient sperm. If these techniques fail, sperm may be found using more advanced methods.
MESA (Microscopic Epididymal Sperm Extraction)
MESA is a technique for collecting sperm that involves using a surgical microscope to open the small tubes within the epididymis to look for sperm. This technique works well in conditions where sperm are being produced in adequate numbers but are blocked from traveling from the testicle to the ejaculate. Examples of such conditions include a prior vasectomy, prior hernia repair with mesh, blockage of the seminal vesicles, cystic fibrosis, and immotile cilia syndrome. This is the favored approach when harvesting sperm after a vasectomy.
An operating microscope and special skills are necessary to identify the tubes most likely to contain sperm and the samples are immediately examined to look for sperm. Sperm harvested from the epididymis is generally considered better quality than sperm harvested directly from the testicle because they have had more time to mature.
This procedure requires a general or spinal anesthetic and involves an incision in the scrotum to gain access to one or both testicles. The sperm harvested can be used immediately or frozen for use at a later time. In cases where no sperm are found, it is necessary to look inside the testicle for viable sperm, a procedure called TESE or testicular sperm extraction.
TESE (Testicular Sperm Extraction)
TESE is very similar to the MESA procedure. In a TESE, the tissue is taken directly from the testicle and examined for the presence of sperm. This technique is very successful in cases of obstructive azoospermia where there is blockage of the tubes responsible for transporting sperm from the testicle to the ejaculate. However, TESE can also be very useful in patients with non-obstructive azoospermia as well. There are several genetic, infection-related and hormonal conditions that lead to low levels of sperm production that can be uncovered through surgery.
TESE or micro-TESE (performed with a microscope) requires general or spinal anesthesia and an incision on the scrotum to gain access to the testicles. Depending on the underlying medical condition, the testicle is either incised in several locations to harvest sperm or completely opened to reveal all of the sperm-producing cells. Several samples are taken and immediately examined for the presence of sperm. Any sperm found can be used immediately to fertilize an egg or they can be frozen for later use. The testicle is then repaired and placed back into the scrotum. The testicle is generally able to function normally after the procedure and continue to produce testosterone. This procedure has been successful in finding sperm is many conditions thought to result in infertility such as Klinefelter’s syndrome and congenital absence of the vas deferens.
If there is a high degree of uncertainty about whether sperm will be found, a couple undergoing TESE will often be counseled to have the procedure performed before eggs are harvested or to have a donor sperm sample as a back-up.