The fertility of a couple depends upon several factors in both the male and female partner. Among all cases of infertility in developed countries, about 30 percent can be traced to male factors, 33 percent can be traced to female factors, 33 percent can be traced to factors in both the male and female partners, and 4 to 5 percent cannot be traced to obvious factors in either partner.
When infertility occurs, the male and female partners are evaluated to determine the cause and best treatment options. In the past, men with infertility had few options because there was limited information about causes and even less information about successful treatment. However, new tests have made it possible to determine the causes of male infertility and treatments, and assisted reproductive technologies (ART) offer hope to many couples.
The main sign of male infertility is the inability to conceive a child. There may be no other obvious signs or symptoms. In some cases, however, an underlying problem such as an inherited disorder, hormonal imbalance, dilated veins around the testicle, or a condition that blocks the passage of sperm causes signs and symptoms.
Although most men with male infertility do not notice symptoms other than inability to conceive a child, signs and symptoms associated with male infertility include:
- Problems with sexual function — for example, difficulty with ejaculation or small volumes of fluid ejaculated, reduced sexual desire or difficulty maintaining an erection (erectile dysfunction)
- Pain, swelling or a lump in the testicle area
- Recurrent respiratory infections
- Inability to smell
- Abnormal breast growth (gynecomastia)
- Decreased facial or body hair or other signs of a chromosomal or hormonal abnormality
- Having a lower than normal sperm count (fewer than 15 million sperm per milliliter of semen or a total sperm count of less than 39 million per ejaculate)
Known causes of male infertility
|Sperm production problems||• Chromosomal or genetic causes
• Undescended testes (failure of
the testes to descend at birth)
• Torsion (twisting of the testis in scrotum)
• Varicocele (varicose veins of the testes)
• Medicines and chemicals
• Radiation damage
• Unknown cause
|Blockage of sperm transport||• Infections
• Prostate-related problems
• Absence of vas deferens
(erection and ejaculation problems)
|• Retrograde and premature ejaculation
• Failure of ejaculation
• Erectile dysfunction
• Infrequent intercourse
• Spinal cord injury
• Prostate surgery
• Damage to nerves
• Some medicines
|Hormonal problems||• Pituitary tumours
• Congenital lack of LH/FSH (pituitary problem from birth)
• Anabolic (androgenic) steroid abuse
|Sperm antibodies||• Vasectomy
• Injury or infection in the epididymis
• Unknown cause
The male reproductive system
The male reproductive system is made up of the testes, a system of ducts (tubes) and other glands that open into the ducts. The brain plays an important part in the control of the male reproductive system.
The pituitary gland and the hypothalamus, located at the base of the brain, control the production of male hormones and sperm. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) are the two important messenger hormones made by the pituitary gland that act on the testes.
The testes (testis: singular) are a pair of egg-shaped glands that sit in the scrotum next to the base of the penis on the outside of the body. The testes make sperm and the male sex hormone testosterone. It takes about 70 days for sperm to become mature and able to fertilise an egg.
When released from the testes, the sperm spend two to 10 days passing through the epididymis where they gain the vital ability to swim strongly (become ‘motile’), and to attach to and penetrate (get into) the egg.
At orgasm, waves of muscle contractions transport the sperm, with a small amount of fluid, from the testes through to the vas deferens. The seminal vesicles and prostate contribute extra fluid to protect the sperm. This mixture of sperm and fluid (the semen) travels along the urethra to the tip of the penis where it is ejaculated (released).
Even in the absence of systemic illness, poor general health will impair fertility.
- Obesity may impair fertility. Aim for an ideal body mass index (BMI). In those who are overweight (BMI 25-30) and obese (BMI >30), there is a relationship between the degree of excessive weight and poor quality and quantity of sperm. Men who have a BMI of >30 should be informed that they are likely to have reduced fertility.
- The adverse effects of smoking on male fertility are well documented.
- Tight-fitting underwear affects semen quality. Men should be informed that although there is an association between elevated scrotal temperature and reduced semen quality, it is still uncertain whether wearing loose-fitting underwear improves fertility.
- Excessive alcohol consumption is known to impair fertility. There is no evidence that drinking within recommended limits has an impact.
- Anabolic androgenic steroids, marijuana, opioid narcotics, cocaine and methamfetamines have an adverse impact on male fertility, and adverse effects have been reported on the hypothalamic-pituitary-testicular axis, sperm function and testicular structure.
Disorders of the testis and spermatogenesis
These may be structural or hormonal.
- Persistent azoospermia is incompatible with fertility. Whilst a low sperm count is a poor prognostic feature, and the lower the count the worse the prognosis, it is not totally incompatible with fertility.
- A number of genetic disorders may be associated with infertility. These include:
- Klinefelter’s syndrome with karyotype XXY, which is associated with hypogonadism and disorders of spermatogenesis. This is the most common sex chromosome disorder associated with infertility.
- Kallman syndrome, which causes hypogonadotrophic hypogonadism.
- Testicular feminisation (or androgen insensitivity syndrome), which is a condition where there is resistance to the virilising effects of androgens, and a child with an XY karyotype appears as a girl. This can be much less complete and more limited resistance to androgens can lead to poor development of the testes.
- Cryptorchidism/ Undescended Testes is often associated with testicular dysgenesis and is a risk factor for infertility. Early orchidopexy (6-12 months of age) is beneficial for testicular growth and may improve spermatogenesis in adulthood. The optimal time for surgery is still unclear.
- The presence of Varicocele in some men is associated with progressive testicular damage from adolescence onwards and a consequent reduction in fertility. However, although the treatment of varicocele in adolescents may be effective, there is a significant risk of overtreatment. European guidelines advise that varicocele repair may be effective in men with subnormal semen analysis, a clinical varicocele and otherwise unexplained infertility over at least two years. Guidelines from the UK’s National Institute for Health and Care Excellence (NICE), however, do not advocate surgery for varicocele as treatment for infertility.
- Testicular tumours are usually treated by orchidectomy, possibly followed by radiotherapy. Treatment of testicular cancer reduces fertility.
- Trauma can cause testicular damage.
- Pituitary causes include:
- Pituitary tumours will displace or destroy normal tissue and the production of follicle-stimulating hormone (FSH) and luteinising hormone (LH) is often the first to be affected.
- Hyperprolactinaemia must be severe – ≥735 mU/L (usually due to a pituitary tumour) – to have an effect on sexual function. It may impair sexual desire, testosterone production and erectile function.
- Panhypopituitarism (unrelated to pregnancy) is called Simmonds’ disease.
- Cushing’s disease.
Disorders of the genital tract
- Failure of adequate differentiation of the embryonic testis can cause failure of proper development of the spermatic ducts.
- In vasectomy the objective is to interrupt the vas deferens and it may be possible to reunite this in an attempt to reverse the procedure; however, the success rate as measured by successful pregnancy is poor.
- Congenital urogenital abnormalities such as hypospadias can cause problems. It tends to deposit the semen in the acid environment of the vagina rather than near the friendlier environment of the cervix.
- Obstruction in the epididymis, or ejaculatory or seminal ducts may be congenital or acquired (for example, as a consequence of infection, trauma or surgery) and may cause azoospermia. A functional obstruction can occur secondary to medication such as selective serotonin reuptake inhibitors (SSRIs).
Other causes include:
- Disorders of ejaculation (eg, anejaculation, retrograde ejaculation).
- Erectile dysfunction
- Idiopathic. The cause is unknown in around 44% of infertile men.
Investigation for the cause of infertility or subfertility should be systematic and led by clinical features, not a blind screening process for everything, so history is important to narrow the field of potential tests.
- Ask about smoking and alcohol.
- Establish the length of time the couple has been trying to conceive and about contraception used prior to this.
- Ask about prior fertility.
- Note family history, particularly of genetic disorders.
- Take a sexual history. Ask about coitus, which must be satisfactory and occurring on a frequent basis, preferably two to three times a week. Consider absences, physical or emotional problems and erectile dysfunction. Ascertain if there are ejaculatory problems – particular attention must be paid to the characteristics of micturition and ejaculation:
- Presence of nocturnal emission.
- Ejaculatory ability in given circumstances.
- Primary or acquired disorder.
- Consider psychosexual aspects (eg, features of affective relationship, pre-existent psychological trauma, previous psychological therapy).
- Direct questioning. Ask about haematospermia, urinary irritability, obstructive urinary symptoms, painful ejaculation, and hot flushes.
- Note previous medical and surgical history. Particularly ask about a past history of mumps (which may cause orchitis), urinary conditions (prostatitis, urethritis) and previous surgery around the genital area (hernia repair, orchidopexy, vasectomy etc). Establish if there is a history of torsion of the testis, which may be relevant, as failure to reduce it swiftly can compromise blood supply and cause lasting damage. Ask about history of sexually transmitted infections (STIs).
- Note previous treatment for malignancy:
- Chemotherapeutic agents, such as those used in childhood leukaemia, may result in subsequent sterility.
- Surgery and radiotherapy may be relevant if they involved the region.
- In men about to receive chemotherapy, the question of sperm banking needs to be considered. Retention of fertility for prepubertal boys with malignancy is a growing field.
- Drug and medication history. Ask about any recreational drug use and about prescribed medication. As well as recreational drugs (as discussed under ‘General health’, above), prescribed medication may adversely affect fertility:
- Phenothiazines and the older typical antipsychotics as well as metoclopramide increase levels of prolactin.
- Oral and rectal sulfasalazine impair spermatogenesis. This is reversible when the drug is withdrawn or switched to mesalazine.
- Immunosuppressants – eg, for autoimmune disease or after transplantation.
- Antidepressants – may interfere with erectile function as well as seminal tube function.