Infertility is the inability to conceive (reproduce) after at least one year of unprotected intercourse. Since most people are able to conceive within this time, physicians recommend that couples unable to do so be assessed for fertility problems. In men, hormone disorders, illness, reproductive anatomy trauma and obstruction, and sexual dysfunction can temporarily or permanently affect sperm and prevent conception. Some disorders become more difficult to treat the longer they persist without treatment.
Sperm development (spermatogenesis) takes place in the seminiferous tubules (ducts) of the testes. Cell division produces spermatozoa (mature sperm cells) that contain one-half of a man's genetic code. Each spermatogenesis cycle consists of six stages and takes about 16 days to complete. Approximately five cycles, or 2 ½ months, are needed to produce one mature sperm. Mitochondria (energy-generating organelles) inside each sperm power its tail (flagellum) so that it can swim to the female egg once inside the vagina. Sperm development is ultimately controlled by the endocrine (hormonal) system that comprises the hypothalamic-pituitary-gonadal axis.
Because sperm development takes over 2 months, illness that was present during the first cycle may affect mature sperm, regardless of a man's health at the time of examination.
According to the National Institutes of Health, male infertility is involved in approximately 40% of the 2.6 million infertile married couples in the United States. One-half of these men experience irreversible infertility and cannot father children, and a small number of these cases are caused by a treatable medical condition.
The primary causes of male infertility are problems with sperm production or delivery. Impaired production or delivery may result from hormonal dysfunction, trauma or defect in the reproductive system, and illness:
Certain drugs used to treat hypertension, arthritis, and digestive disease, as well as chemotherapy drugs are associated with sperm production problems and infertility.
Retrograde ejaculation occurs when impairment of the muscles or nerves of the bladder neck prohibit it from closing during ejaculation, allowing semen to flow backwards into the bladder. It may result from bladder surgery, a developmental defect in the urethra or bladder, or disease that affects the nervous system, including diabetes. Diminished or "dry" ejaculation and cloudy urine after ejaculation may be signs of this condition.
Inflammatory infections of the prostate (prostatitis), epididymis (epididymitis), and testicles (orchitis), can cause irreversible infertility if they occur before puberty.
Testicular trauma, resulting from injury, surgery, or infection can trigger an immune response in the testes that may damage sperm. Though their effects are not fully understood, antibodies can impair a sperm cell's ability to swim through cervical mucus or to penetrate a female egg.
The search for an infertility cause usually begins with the male, because male examination and testing is less complicated. A thorough examination and a review of the man's medical and surgical history are necessary, because chronic disease, pelvic injury, childhood illness, abdominal or reproductive organ surgery, recreational drug use, and medications can affect fertility. Physical examination may detect testicular irregularities (e.g., vericocele, absence of vas deferens, tumor), evidence of hormonal disorders (e.g., underdeveloped reproductive organs, enlarged breast tissue, or evidence of testosterone deficiency).
Assessing reproductive-fertility history is important; specialists typically inquire about the following:
A semen analysis, usually performed by a fertility specialist, is used to examine the entire ejaculate, because seminal fluid can affect sperm function and movement. Generally, three semen samples are taken at different times to account for variables such as temperature and error. Most specialists prefer three samples that differ no more than 20% from one another before proceeding with diagnosis.
Six sperm factors are analyzed in semen analysis:
Azoospermia is the absence of sperm in the semen. Men with normal reproductive tracts and hormone systems can have azoospermia due to a lack of sperm-producing tissue in the testes or an obstruction. Obstructions can be viewed with x-ray. The World Health Organization has established criteria for normal sperm concentration, morphology, and motility. Total motile sperm count, which should be about 40 million, is calculated by multiplying volume by concentration by motility.
The semen fluid test looks at factors that may impede sperm performance. Abnormally thick semen may cause sperm to swim more slowly through cervical mucus, obstructing fertilization. Abnormal sperm shape (i.e., disfigured or multiple heads or tails) usually indicates poor sperm health. Infertility is likely if 60% or more of sperm in semen is abnormally shaped.
Other tests are concerned specifically with sperm's ability to swim through cervical mucus and bind to and penetrate an egg. The postcoital Sims-Huhmer, or sperm-mucus interaction test, examines whether the sperm are able to swim through the female reproductive tract. This ability is referred to as forward progression. In the middle of the menstrual cycle, the cervical mucus becomes watery. Intercourse is recommended during this time, followed, the next day, with an inspection of the mucus to determine if:
The sperm penetration assay (SPA), or sperm-oocyte interaction test, examines the ability of sperm to penetrate the egg by combining it with a hamster egg. The immunobead test looks at semen for the presence of antibodies that damage sperm.
Post-ejaculation urinalysis may identify diseases that affect fertility, such as kidney disease, diabetes, and repeated urinary tract infection (UTI). Blood tests identify disorders that impair testosterone and sperm production.
At least one-half of male fertility problems can be treated so that conception is possible. There are three categories of treatment:
Therapy includes methods to improve erectile dysfunction, induce ejaculation, obtain sperm, and inseminate an egg:
These procedures are done under local anesthesia, usually take about 30 minutes, and cause pain and swelling.
Sperm retrieved by MESA, PESA, or TESE may be used in in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). IVF involves combining eggs with sperm in a laboratory, providing proper fertilization conditions, and transferring the resulting embryos to the uterus. To retrieve an egg, a specialist uses ultrasound to guide a fine needle through the vaginal wall and into the ovary or makes an incision in the abdomen to get to the ovary (laparoscopy). Once the eggs are retrieved, they are combined with prepared sperm in a sterile dish for 2 to 4 days. After fertilization, the embryos are transferred to the uterus. IVF is used most commonly for infertility caused by female reproductive abnormalities.
Intracytoplasmic sperm injection (ICSI) may be used with immotile sperm during in vitro fertilization. Using a tiny glass needle, one sperm is injected directly into a retrieved mature egg. The egg is incubated and transferred to the uterus.
Fertilization occurs in 50% to 80% of cases and approximately 30% result in a live birth. The egg may fail to divide or the embryo may arrest at an early stage of development. Younger patients achieve more favorable results and poor egg quality and advanced maternal age result in lower success rates.
ICSI does not increase the incidence of multiple pregnancies. Long-term information about the health and fertility of children conceived through this procedure is not available because it was first performed in 1992.
While excess sperm from MESA or PESA can usually be frozen for future use, most TESE-derived sperm are not of sufficient quality or quantity for frozen storage (cryopreservation). Multiple MESA or PESA procedures are not recommended, since repetition can lead to scarring.
Average conception rate for these procedures is about 30%.
Drug therapy includes medications to improve sperm production, treat hormonal dysfunction, cure infections that compromise sperm, and fight sperm antibodies. The administration of testosterone is similar to that used to treat testosterone deficiency. Tamoxifen (Nolvadex®), an antiestrogen agent, may be used to stimulate gonadotropin (male hormone) release, which leads to testosterone production. Antibiotics, like levofloxacin (Levaquin®) and doxycycline (Periostat®), are used to treat fertility-impairing infections of the urinary tract, testes, and prostate, and STDs.
Surgery is performed to treat reproductive tract obstruction and vericocele. Vasoepididymostomy is a microsurgical procedure that corrects obstruction in the epididymis (coiled tube that connects the testes with the vas deferens). Obstructions commonly result from STDs and also include cysts and tubal closure (atresia), which is usually genetic. Vericocelectomy, the removal of a varicocele from the testes, often results in increased sperm count.