To achieve fertilization, sperm must have proper shape, good health, and rapid movement to reach a woman’s egg. Although infertility is largely thought of as a female issue, male infertility accounts for approximately 40 percent of infertility problems, according to the National Institute of Health.
The man’s endocrine (hormonal) system controls sperm development, which occurs in the testes. Once fully developed, sperm are ejaculated in 2 to 5 milliliters (one-fourteenth to one-sixth of a fluid ounce) of semen. The sperm count – the number of sperm cells per milliliter of semen – is important in determining fertility. A count of 15 million to 20 million sperm per milliliter or higher is considered normal. Sub-fertile men have a sperm count of 5 million to 10 million sperm per milliliter or less.
Normal sperm movement is determined by at least half of the sperm showing rapid or progressive sustained movement for at least three hours after the sample liquefies. Normal sperm vitality is at least 50 percent of live sperm in the sample. Normal morphology is indicated when 14 percent of the sperm have a standard physical appearance, especially the head and tail features which allow the sperm to swim to the egg.
In the first stage of diagnosing male infertility, the doctor will ask the male patient to obtain a semen sample through masturbation. In some circumstances, special techniques such as electric stimulation or urological surgery are required to obtain a sample.
The urologist performs a surgical procedure called a Microscopic Epididymal Aspiration (MESA) to obtain sperm from the duct (epididymis) where sperm are stored and transported from the testicles to the urethra (vas deferens). This technique is used when sperm are obstructed, for example from a vasectomy, the congenital absence of a connecting tube from the testes to the vas deferens, or vas deferens scarring. The surgery, performed under general or local anesthesia, employs an operating microscope to access the epididymis tubules, which contain the sperm and sperm fluid.
The urologist collects the sperm fluid to give to the IVF lab where it will be processed for use or freezing. If the fluid does not contain any sperm, or only dead sperm are present, then another sample will be removed. This process is repeated until enough sperm are obtained for immediate or future use. When eggs are ready to be fertilized, frozen sperm are thawed.
Percutaneous Epididymal Sperm Aspiration (PESA) is a smaller-scale sperm collection technique. A small needle is inserted through the skin of the scrotum to collect sperm from the epididymis. Although PESA is effective, the newer MESA procedure provides urologists a way to collect greater amounts of sperm, which means large quantities can be frozen for future use.
Unlike MESA or PESA, which are used when sperm are stored but blocked, Testicular Excisional Sperm Extraction (TESE) is necessary when the lack of sperm is caused by no existing sperm storage or testicular failure rather than obstruction. This condition is uncommon, but causes of testicular failure include:
TESE urologic surgery removes a small sample of testicle tissue that can be checked for immature sperm for use in Intracytoplasmic Sperm Injection (ICSI). TESE success is limited by the quality of sperm found in the tissue sample. In addition, freezing TESE-obtained sperm seems to decrease success rates, so the procedure should be performed the same day as egg retrieval.
After the sperm sample is obtained, it is analyzed for sperm count, movement, and morphology, and treatment is determined accordingly. Intrauterine insemination (IUI) is usually tried first; if sperm quality renders IUI ineffective, in-vitro fertilization (IVF) may be the next step. With many low sperm production infertility cases, Intracytoplasmic Sperm Injection (ICSI) may be the best option to ensure egg fertilization. In a lab, ICSI uses a microscopic needle to inject a single sperm into an egg. This requires only one motile sperm thereby eliminating sperm count issues.
Without ICSI, the probability of fertilization and pregnancy for men with infertility problems is less than 1 percent. With ICSI, however, the probability of fertilization and pregnancy reaches a similar rate to conventional IVF. Sperm obtained using urologic procedures such as MESA, PESA or TESE require that ICSI be performed.