Inability of a man to produce or deliver sufficient numbers of healthy sperm to achieve fertilization
- In rare cases, may be due to a chromosomal abnormality
- Smoking and drinking alcohol are risk factors
- Age is not a significant factor
In about 1 in 3 couples who have difficulty conceiving, the problem results from male infertility. In men, fertility depends partly on the production of enough normal sperm to make it likely that one of them will fertilize an egg and partly on the ability to deliver the sperm into the vagina during sexual intercourse. If either of these processes is faulty, infertility may result.
What are the causes?
Unlike the causes of female infertility, which are more easily identifiable, the cause of infertility can be difficult to determine in some men. A cause is discovered in only 1 in 3 men investigated.
Problems with sperm production
A low sperm count or the production of abnormal sperm may have various causes. One is a rise in the temperature of the testes. Normally, the testes are about 2°C (4°F) cooler than the rest of the body. Any factors that raise their temperature may reduce the sperm count.
Aspects of your lifestyle that may impair sperm production include smoking, drinking alcohol, using certain medications and re-creational drugs, and wearing tight clothing.
Sperm production can be adversely affected by certain long-term illnesses, such as chronic kidney failure, and by the infectious disease mumps. Conditions affecting the scrotum, such as a varicocele, in which there are varicose veins in the scrotum, may also reduce fertility. In addition, fertility problems may occur if the testes are damaged by medical procedures including surgery, chemotherapy, or radiotherapy for disorders such as cancer of the testis.
Low sperm production may also be due to a hormonal deficiency. Insufficient production of the sex hormone testosterone by the testes (see Hypogonadism in males) can cause a low sperm count. Since the pituitary gland controls testosterone secretion, pituitary disorders, such as a tumour (see Prolactinoma), may also lead to reduced sperm production. Rarely, low testosterone levels are due to a chromosomal abnormality such as Klinefelter’s syndrome. The most common cause of a low sperm count is idiopathic oligospermia, in which there is a reduced sperm count for no identifiable reason.
Problems with sperm delivery
A number of factors may prevent sperm from reaching the vagina. The most easily identifiable factor is erectile dysfunction, which is the inability to achieve or maintain an erection. Other factors include damage to the epididymides and vas deferens (tubes that transport sperm). This type of damage is often due to a sexually transmitted infection such as gonorrhoea. It may also be caused by retrograde ejaculation, in which semen flows back into the bladder when the valves at the outlet of the bladder neck do not close properly. Retrograde ejaculation can also occur following surgery of the prostate gland (see Partial prostatectomy, and Radical prostatectomy).
What might be done?
Your doctor will ask about your health, medical history, and sex life. He or she will give you a physical examination, including an examination of your genitals. You will also need to provide samples of your semen (see Semen analysis). If your sperm count is low or if many of your sperm are abnormal, you may have further investigations such as blood tests to check your hormone levels.
The underlying cause will be treated, if possible. For example, low testosterone levels can be treated with injections of hormones (see Sex hormones and related drugs). Various treatments are available for erectile dysfunction. Damage to the epididymides or vas deferens can be treated by microsurgery. If the underlying cause of the infertility cannot be treated, there are various measures that can be taken to increase the chance of conception. For example, artificial insemination may be used in cases of erectile dysfunction that do not respond to treatment. Artificial insemination may also be used for retrograde ejaculation; alternatively, sperm may be taken from the urine. If you produce only a few healthy sperm, single sperm may be taken from the semen or directly from the epididymis or testis. A process called intracytoplasmic sperm injection (ICSI) may then be used to fertilize an egg. In ICSI, an individual sperm is injected directly into an egg, which is obtained in the same way as in IVF. The fertilized egg is then placed in the woman’s uterus. In some cases, donor sperm may be considered.
What is the prognosis?
If the infertility is treatable, the chance of regaining fertility is high. Artificial insemination gives a 10–15 per cent chance of conceiving in one menstrual cycle. Each attempt at assisted conception or ICSI is successful in 15–30 per cent of cases, depending on the technique.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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