A complete failure of emission and ejaculation occurs most commonly from spinal cord injury (10,000 cases/ year in the United States) and as a result of deep pelvic or retroperitoneal surgery that injures the pelvic sympathetic nerves. With rectal probe electroejaculation, the pelvic sympathetic nerves undergo controlled stimulation, with contraction of the vas deferens, seminal vesicle, and prostate, such that a reflex ejaculation is induced. The semen is collected from the penis and the bladder, as retrograde ejaculation is often associated with electroejaculation. Semen acquired in this way generally requires assisted reproductive technology for success.

In men with anejaculation after retroperitoneal surgery or spinal trauma, successful recovery of sperm with electroejaculation is possible in the vast majority of patients. Sperm motility tends to be lower than normal when obtained in this way, an effect independent of electrical or heat effects inherent to the procedure. In men with spinal cord injuries above the T5 level, it is often possible to induce a reflex ejaculation with high-frequency penile vibration, termed vibratory stimulation. With the use of handheld vibrators set to a frequency of 100 cycles/s at an amplitude of 2-3 mm, patients may be taught to perform the procedure and attempt to conceive at home with cervical insemination.

Sperm Aspiration

Sperm aspiration techniques are indicated for men in whom the transport of sperm is not possible because the ductal system is absent or surgically unreconstructable. An example of this is vasal agenesis. Acquired forms of obstruction may also exist, the most common of which is failed vasectomy reversal. Aspiration procedures can involve microsurgery to collect sperm from the sperm reservoirs within the genital tract. At present, sperm are routinely aspirated from the vas deferens, epididymis, or testicle. It is important to realize that IVF is required to achieve a pregnancy with these procedures. Thus, success rates are intimately tied to a complex program of assisted reproduction for both partners (

Table 42-16). In cases of sperm aspiration from the testicle and epididymis, IVF along with ICSI is required. An obvious prerequisite for these procedures is ongoing sperm production. Although evaluated indirectly by hormone levels and testis volume, the most direct way to verify sperm production is with a testis biopsy.

A. Vasal Aspiration
After a scrotal incision and with an operating microscope, a vasotomy is made, and leaking sperm are aspirated into culture medium. Once enough sperm are obtained (> 10-20 million), the vasotomy is closed with microscopic sutures. Vasal aspiration provides the most mature or fertilizable sperm, as they have already passed through the epididymis, where sperm maturation is completed.

B. Epididymal Sperm Aspiration
Epididymal sperm aspiration is performed when the vas is not present or is scarred and unusable. Sperm are directly collected from a single, isolated epididymal tubule (

Figure 42-16). After sperm are obtained, the epididymal tubule is closed with microscopic suture, and the sperm are processed. Epididymal sperm are not as mature as vasal sperm; as a consequence, epididymal sperm require ICSI to fertilize the egg. Egg fertilization rates of 65% and pregnancy rates of 50% are possible with epididymal sperm, but results vary among individuals because of differences in sperm and egg quality.

C. Testis Sperm Retrieval
The most recently developed aspiration technique is testicular sperm retrieval, begun in 1995. It is a breakthrough in that it demonstrates that sperm do not have to pass through the epididymis to fertilize the egg. Testicular sperm extraction is indicated for patients in whom there is an unreconstructable blockage in the epididymis, or in cases of severe testis failure, in which so few sperm are produced that they cannot reach the ejaculate. In this procedure, a small piece of testis tissue is taken in a manner similar to that of a regular testis biopsy. The testis tissue is specially treated in the laboratory to separate sperm from other cells. High egg fertilization rates (50-65%) and pregnancy rates (40- 50%) are possible with testis sperm.