Male infertility is a fairly common problem. While approximately 15% of all U.S. couples are infertile, up to 50% of infertile couples have a male factor fertility problem and of these, 20% will not be able to conceive solely because of an impaired male factor.
Risk factors for male infertility can be divided into four categories: testicular factors, environmental factors containing agents harmful to the testicles, iatrogenic (medical treatment related) factors and sex related factors. Testicular factors include undescended testes, testicular torsion (twisting), varicoceles (dilated veins around the testicle) and testicular infections. Environmental toxins to the testicle are chemicals, drugs or other substances that poison sperm-producing organs. Iatrogenic factors are caused by various medical treatments or diagnostic procedures, and include a history of prostate, scrotal or groin-area surgeries, such as a vasectomy or hernia repair, as well as the use of certain medications. Sex related factors include erectile dysfunction, premature ejaculation, retrograde ejaculation, failure to achieve vaginal penetration and poorly timed or infrequent intercourse.
Many of the above-mentioned risk factors produce harmful or negative effects on semen quality. A complete semen analysis will include information about ejaculate volume, sperm count, motility (movement), whether the sperm are moving in a normal direction, and the morphology (shape) of the sperm. There is a statistical decrease in fertility rates as sperm counts fall below 20 million per milliliter, and where abnormal motility or sperm morphology is present.
Undescended testicle occurs in approximately 0.8% of one-year-old boys and, if left untreated, can result in male infertility. The undescended testicle is located in the groin or abdomen, where higher temperatures can decrease sperm production. Boys with untreated undescended testicles on both sides will most likely be sterile. Approximately 71% of boys with an untreated undescended testicle on one side will likely have subfertile semen. Studies have shown that by the time a child is two-years-old, there are significantly fewer sperm-producing cells in the undescended testicle than in the normal testicle. Thus, surgical correction of an undescended testicle before the age of two should reduce the risk of male infertility.
Testicular torsion, or twisting of the testicle on the spermatic cord which interferes with its normal blood supply, occurs in approximately one in 4,000 male children and adolescents and can lead to male infertility. Testicular torsion is a surgical emergency; surgical correction within 8-12 hours helps preserve fertility. Approximately 30% to 40% of men with a history of testicular torsion will have abnormal semen analyses.
Varicoceles (dilated veins around the testicle) result from enlargement of the testicular veins. The dilation of these veins is thought to be due to incompetent venous valves. It is believed that these dilated veins cause an increase in testicular temperature, which impairs sperm production. Varicoceles occur in approximately 15% of the general population, but are found in up to 50% of men with primary infertility and up to 69% of men with secondary infertility (those who have once fathered a child but are no longer able to do so). However, within two years after a successful varicocele repair, improvement in semen is expected in up to 70% of men, and pregnancy in up to 40% of couples.
Infections of the genital tract, such as those of the prostate, epididymis or testicle can lead to male infertility. Up to 15% of male infertility can be linked to sexual transmitted diseases. A history of mumps after puberty is also important, because up to 30% of these males also develop diminished function of the testicle and sperm production. Vaccination against the mumps virus has helped eliminate this cause of male infertility.
Recreational drugs such as alcohol, cocaine, cigarette smoking and marijuana are all risk factors for male infertility. Studies have shown that smoking more than 20 cigarettes per day has a negative effect on sperm count and motility. Marijuana has also been shown to decrease sperm quality. While mild to moderate alcohol consumption has not been shown to affect semen quality, high alcohol use has been associated with low testosterone levels and a decrease in semen volume.
There are numerous medications that contribute to male infertility. Examples include antihypertensive medications, such as spironolactone (Aldactone) and calcium channel blockers, and medications used to treat gout, such as colchicine and allopurinol (Zyloprim). Prescription medications such as cimetadine (Tagamet), ketoconazole (Nizoral), and sulfasalazine (Azulfidine), are other known gonadotoxic agents. Chemotherapy and radiation to the genital area also impair sperm production. Therefore, it is important for young men to consider banking sperm prior to undergoing treatment for cancer. Finally, environmental toxins, such as solvents, heavy metals and some pesticides, as well as exposures to heat, such as frequent hot tub usage, have also been shown to impair sperm production.
The harmful effect is usually reversible if the toxic substance is identified and the exposure is discontinued.
Up to 7% of men have injury to, or obstruction of, their vas deferens after inguinal hernia repairs (in the groin area). Recent evidence suggests that mesh used during the surgical repair of an inguinal hernia can result in scar tissue around the vas deferens and cause obstruction. Therefore, the use of prosthetic mesh during an inguinal hernia repair should be avoided in men who wish to preserve fertility.
Retrograde ejaculation refers to the entry of semen into the male’s bladder instead of going out forward through the urethra during ejaculation. Medications that cause retrograde ejaculation include alpha blockers used to treat prostate enlargement and anti-hypertensive medications, such as prazosin (Minipress) and terazosin (Hytrin). Surgical procedures to treat an enlarged prostate gland can also lead to retrograde ejaculation. However, the sperm can be collected from the urine and used for successful insemination.
Operations that remove the prostate gland are associated with possible nerve injury, which can lead to erectile dysfunction.
Coital factors cause infertility in approximately 5% of patients seeking treatment. Couples trying to get pregnant should have intercourse every 48 hours around the time of ovulation, because sperm have been shown to live for approximately two days in the cervical mucus. One study has shown that fertile couples who have intercourse less than once a week had a pregnancy rate of 16.7% over 6 months, whereas 83.3% of couples who had intercourse four times a week conceived. The use of most lubricants should be avoided since products such as Lubifax, Surgilube, Keri Lotion and K-Y Jelly result in decreased sperm movement; if needed, vegetable oil or special lubricants that do not affect sperm can be used.
Other coital factors include erectile dysfunction, premature ejaculation, lack of ejaculation, retrograde ejaculation, failure to vaginally penetrate due to severe penile deformities, and poorly timed intercourse. One study has shown that 21% of infertile men did not know their wife’s fertile time. Another study has shown that the treatment of impotence, premature ejaculation and retrograde ejaculation, as well as education concerning other sexual causes of male infertility, can lead to a pregnancy rate of up to 78% of otherwise healthy couples. Most coital factors of male infertility can be addressed through education and counseling.
It is also important to remember that up to 25% of male infertility is due to unknown causes, now many of which are thought to be genetic Like advanced maternal age, advanced paternal age is also considered a risk factor for male infertility. Because fertility decreases with age, couples should not delay seeking advice from infertility specialists whenever there is a concern regarding their fertility.