No longer are millions of swimming sperm required to fertilize a singe egg. The development of in vitro fertility (IVF) and intracytoplasmic sperm injection (ICSI) have changed the biological requirements for human reproduction. Now only a single sperm is required, and it doesn’t even have to be moving. Using an extremely fine glass pipette, an embryologist can inject a single sperm into a woman’s egg with resulting fertilization and embryo formation. The embryos are then transferred into the woman’s uterus where pregnancy ensues. This technology was first applied to ejaculated sperm, but it was soon discovered that sperm surgically extracted out of a man’s reproductive organs would work as well.
Various techniques for extracting sperm from a man’s reproductive organs have been perfected. These techniques initially were performed on men with anatomical blockages which could not be surgically corrected. Subsequently it was discovered that men without enough sperm production to show any sperm at all in their semen analysis may still be making low levels of sperm in their testicles and sperm could be retrieved from the testicles directly for successful IVF-ICSI pregnancies. Furthermore, as the availability and success of IVF has markedly increased, many men with vasectomies, who would otherwise be surgically reconstructable, are encouraged to undergo sperm retrieval instead. Likewise, patients with neurological disorders or nerve damage who are unable to ejaculate naturally may also undergo sperm retrieval instead of the traditional treatment of electrical stimulation of the ejaculatory nerves to induce an artificial ejaculation (termed “electro ejaculation”).
Normally, when a man ejaculates, sperm that was produced in the testicles and stored in the epididymis is squeezed up the vas deferens to the prostate where it is admixed with fluids from the prostate and seminal vesicles. This mixture is then forcefully squeezed forward and out the urethra of the penis. Experience and research has led to the understanding that the fluids from the prostate and seminal vesicles are essential for the sperm's ability to swim to the egg, penetrate the egg and fertilize it. Without these fluids as they are found in the ejaculate, the sperm itself will not be able to fertilize an egg on its own. Therefore, when a man undergoes sperm retrieval, that sperm cannot be used for artificial insemination. It can only be used with IVF and intra-cytoplasmic sperm injection.
Sperm may be retrieved from the male reproductive organs through a surgical incision or percutaneously through a needle. The technique chosen is primarily determined by whether the man’s underlying problem is a blockage to the transport of sperm or a failure of the testicles to produce sperm normally. In the case of a blockage, there is typically normal ongoing sperm production. Sperm will therefore be plentiful in the testicle as well as the epididymis where it is stored after it is produced. In this situation, a surgical exploration of the testicle and epididymis will allow the surgeon to retrieve the abundant sperm from either the testicle or the epididymis. Because of the normal level of sperm production in the case of a blockage, a percutaneous approach with a needle passed through the skin of the scrotum is also likely to retrieve sperm easily.
On the other hand, in the case of poor sperm production, where there is no sperm in the ejaculation, but still potentially very low levels of production still in the testicle, there is unlikely to be sperm stored in the epididymis. Since, at best, only relatively small numbers of sperm are being produced, the yield in the epididymis is minimal or nil, and sperm must be retrieved directly from the testicle itself. Furthermore, since the quantity of sperm is so low in this situation, a percutaneous approach with a needle is not likely to find the sperm. Therefore in the case of poor sperm production, surgical retrieval from the testicle is recommended.
Techniques of Sperm Retrieval
The various sperm retrieval techniques are termed:
Microsurgical Epididymal Sperm Aspiration (MESA): An incision is made through the scrotal skin. The testicle and epididymis are brought into view. The epididymis tube is carefully incised to release the sperm-filled fluid inside it. The fluid is harvested by suction through a delicate syringe. This procedure is reserved for men who have a blockage, but otherwise normal sperm production. The amount of sperm retrieved is typically very large and can be used immediately for intracytoplasmic injection into an egg, or can be frozen in several batches for subsequent cycles of IVF-ICSI, should they be necessary. In many cases, enough sperm can be retrieved for as many cycles of IVF as a couple would ever possibly undergo. The procedure is performed with optical magnification, such as an operating microscope.
Percutaneous Epididymal Sperm Aspiration (PESA): This technique is appropriate for a man with a blockage. A needle is passed through the scrotal skin and into the epididymis. The needle is attached to a syringe that generates suction to aspirate out sperm-filled fluid. Because the epididymis tube is very small and tightly coiled, the fluid is not easily withdrawn as when blood is taken from a vein. Rather, very small amounts of fluid must be gently coaxed up through the needle. This procedure is reserved for a man who has a blockage, but otherwise normal sperm production. The yield is generally adequate for a single cycle of IVF-ICSI but not necessarily enough to be reliably frozen and thawed for later use; therefore, this procedure must be performed on the same day as the wife’s egg retrieval, and it usually must be repeated if a subsequent cycle of IVF-ICSI is required by the couple.
Testicular Sperm Extraction(TeSE): Through a small scrotal skin incision, the testicle is explored. Small pieces of tissue are cut directly out of the testicle and sperm is extracted from this tissue by the embryologist. This technique is appropriate for a man with a blockage or for a man with poor sperm production. In cases of poor production, multiple excisions may be required to find an area containing sperm. In this situation, the sperm must typically be used within 24 hours of harvest. In a patient with a blockage, the sperm are plentiful enough to survive freezing of the tissue for later use.
Testicular Sperm Aspiration (TeSA): A needle connected to a syringe is passed through the scrotal skin into the testicle. With syringe suction and numerous excursions of the needle through the testicle tissue, a very small amount of testicular tissue can be retrieved. In the case of obstruction it will usually be adequate for a cycle of IVF-ICSI that day, but not for freezing and subsequent use. In the case of poor sperm production, this technique may be performed through multiple entry points in the testicle in an effort to localize where sperm production may be occurring for subsequent open TESE.
Testis PercBiopsy: A larger gauge biopsy core needle is passed through the skin of the scrotum and fired into the testicle. The yield is greater than with an aspirating syringe, but the tissue is still typically used on the same day as egg retrieval, and the technique is typically performed on a patient with a blockage.
Testis Micro dissection: An incision is made in the scrotal skin and the testicle is explored. The inner contents of the testicle are dissected with the aid of an operating microscope. Small areas of sperm production are identified by their appearance under the microscope and these areas are removed and handed off to the embryologist who extracts the sperm from the tissue. This technique is reserved for patients with very low levels of sperm production where extensive searching throughout the testicle is required.
The incisional procedures that include MESA, TeSE, and Testicular Micro dissection are often performed with a general anesthesia or IV sedation, but may be performed with a local anesthetic. The perutaneous procedures, which include PESA, TeSA, and PercBiopsy, are often performed with a local anesthesia with or without light sedation. All procedures are outpatient based. The recovery from the incisional procedures is similar to that of a vasectomy—about one week of no sex or exercise and 48 hours of very limited activity. The recovery from a percutaneous procedure is less.
The risks of the various retrieval procedures are similar, mainly bleeding, infection, and permanent damage to the testicle resulting in shrinkage and possibly the need for lifelong testosterone supplementation. Fortunately these complications are uncommon. Procedures such as MESA and PESA potentially scar the epididymis in such a way as to make a subsequent vasectomy reversal unable to be performed on that side.
Sperm retrieval procedures coupled with IVF-ICSI has enabled men who are surgically unreconstructable and men who have severely low sperm production to father children. Due to the costs and risks involved to both partners, the consensus statement of the American Society of Reproductive Medicine is that for men who have had a vasectomy and whose partners have no known infertility risk factors, vasectomy reversal is recommended over sperm retrieval with IVF-ICSI.
