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Tuesday, December 1, 2020

THERAPEUTIC SPERM RETRIEVAL

THERAPEUTIC SPERM RETRIEVAL

Sperm retrieval techniques collect sperm from organs within the male genital tract. Developed in 1985, ten years before the description of intracytoplasmic sperm injection (ICSI), sperm retrieval combined with in vitro fertilization (IVF) and ICSI allow severely infertile men the opportunity for fatherhood. Candidate organs for sperm retrieval include the vas deferens, epididymis, and testicle in obstructed men and the testis in nonobstructive azoospermic men. Although it is not difficult to retrieve sperm from men with normal sperm production, it can be very difficult to find sperm in men with testicular failure and nonobstructive azoospermia.

THERAPEUTIC SPERM RETRIEVAL


Patients with congenital or acquired obstruction of the excurrent ductal system at the level of the prostate or the pelvic portions of the vas deferens are candidates for vasal sperm aspiration. Also included are men with ejaculatory failure due to diabetes or spinal cord injury. Vasal aspiration is performed either coincident with, or a day in advance of, IVF egg retrieval and is undertaken in a manner similar to a vasectomy. Through a scrotal puncture, the vas deferens is identified. Using optical magnification, a small incision or puncture is made in the delicate wall of the vas deferens until the lumen is entered. Sperm and fluid are aspirated and, after sufficient sperm are obtained, the vas deferens wall is closed microsurgically; no closure is needed for a puncture vasotomy. Vasal sperm is the most “mature” or fertilizable of all retrieved sperm, having passed through epididymal maturation. This is reflected in the fact that pregnancies have been achieved with vasal sperm and intrauterine insemination (IUI) and IVF without ICSI. Epididymal sperm aspiration is performed when the vas is either absent, such as with congenital absence of the vas deferens (CAVD), or is scarred from prior surgery, trauma, or infection. Two different approaches to epididymal sperm aspiration are microscopic epididymal sperm aspiration (MESA), in which the epididymis is explored microsurgically and sperm aspirated from individual epididymal tubules, and percutaneous epididymal sperm aspiration (PESA), in which sperm are aspirated blindly from the epididymis after percutaneous puncture. The most important difference between these techniques is that individual epididymal tubules are sampled for sperm with MESA, but multiple epididymal tubules are sampled with PESA; thus, the overall yield and bankability of sperm is less with PESA than MESA. As epididymal sperm are not as “mature” as vasal sperm, they require IVF-ICSI for pregnancy success.

The newest of the three sperm aspiration techniques, testicular sperm retrieval, was first reported in 1993, one year after ICSI. It demonstrated that sperm do not have to “mature” and pass through the epididymis to be able to fertilize an egg (with ICSI). Testicular sperm extraction is indicated for “obstructed” patients and is also useful for many men with nonobstructive azoospermia. In obstructed men, testis sperm can be retrieved by needle aspiration (TESA) or percutaneous or open surgical biopsy (TESE). TESA involves holding the testis with the epididymis located posteriorly followed by insertion of a hollow needle (16- to 23-gauge) into the testis through the stretched skin of the scrotum.

In men with nonobstructive azoospermia, testis biopsy (TESE) is usually needed to retrieve sufficient sperm for IVF-ICSI. To improve the likelihood of finding sperm, a multibiopsy TESE has been described in which many biopsies are taken until enough sperm are obtained. A variant of multibiopsy TESE is microdissection TESE, which involves taking multiple testis biopsies through a large incision that exposes the entire testis parenchyma. With an operating microscope, the entire bed of testis tissue is examined for sperm-containing seminiferous tubules that are larger in diameter and more opaque, or whiter, than tubules without active spermatogenesis.

Fine-needle aspiration map-directed TESE employs a diagnostic mapping procedure (see Plate 5-6) to guide subsequent sperm retrieval for IVF-ICSI. Information obtained from the map “directs” the TESE, taking advantage of the a priori knowledge that sperm are present in nonobstructive azoospermic men before IVF-ICSI. Depending on the location, density, and quantity of sperm found on the map, sperm retrieval may involve TESA, TESE, or microdissection TESE. The ability to freeze and thaw retrieved sperm is a significant advance in the care of azoospermic men. It simplifies the timing and orchestration of fertility procedures, adds convenience to reproductive urologists’ schedules, and allows multiple opportunities to conceive with IVF-ICSI without repeating surgical sperm retrieval.


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