Male infertility: causes, diagnosis and treatment

Male infertility is the inability of a man to achieve a pregnancy after 12–24 months of regular unprotected intercourse. The male factor is responsible, alone or in combination with a female factor, for around half of all cases of couple infertility. In most cases it is a diagnosable and treatable condition, managed with medical therapy, surgery, or sperm retrieval techniques combined with assisted reproductive technology.

The World Health Organization defines infertility as the inability of a sexually active, non-contracepting couple to achieve pregnancy within one year. Roughly one couple in four does not conceive within the first 12 months; of these, a minority seek medical treatment and fewer still remain involuntarily childless. A healthy couple aged 25–30 with a regular sex life has approximately a one-in-four chance of conception per cycle.

Male or female factor: where couple infertility originates

Contrary to a long-standing prejudice, responsibility is evenly distributed between the two partners. The classic breakdown is:

• Female factor: roughly one third of cases
• Male factor: roughly one third of cases
• Combined factor (both partners): around 15%
• Unexplained (idiopathic) infertility: the remaining share

This is why the man's andrological assessment should run alongside the woman's gynaecological assessment, not after it. Starting the diagnostic pathway with the female partner alone delays the identification of male causes that are often readily treatable.

Causes of male infertility

Many factors can impair male fertility, temporarily or permanently. A high proportion of these reproductive alterations arise in childhood or at puberty, frequently without obvious symptoms. The main causes are:

• Varicocele: the most frequent cause of male infertility, found in around 40% of infertile men and often surgically correctable
• Prostatitis and genital tract infections affecting the testis (orchitis) and the epididymis — the duct above the testis through which spermatozoa transit
• Sexually transmitted diseases
• Post-mumps orchitis: inflammation of the testis following mumps contracted after puberty, which can cause irreversible damage
• Obstruction of the seminal tract, secondary to infection or to surgery on the genitourinary system
• Cryptorchidism (undescended testis) and testicular torsion
• Scrotal trauma
• Medical treatments: drugs, surgery or radiotherapy, including cancer therapies
• Hormonal disorders affecting the pituitary gland and the testis
• Lifestyle factors: smoking, alcohol and drug use, physical inactivity, stress and obesity all reduce the fertilising capacity of sperm

Diagnosis: how male fertility is assessed

Assessment begins with a detailed medical history and an andrological examination of the external genitalia and the prostate, followed by semen analysis (spermiogram), which measures sperm concentration, motility and morphology. Two semen samples 15–20 days apart are usually required. Depending on the findings, the specialist may add hormone tests, urine cultures, scrotal ultrasound, genetic testing or a sperm DNA fragmentation test. The terms used in the diagnosis:

• Oligozoospermia: reduced sperm concentration
• Asthenozoospermia: reduced sperm motility
• Teratozoospermia: high proportion of abnormally shaped sperm
• OAT syndrome: oligo-astheno-teratozoospermia, when all three abnormalities occur together — the most common presentation
• Cryptozoospermia: sperm present only in extremely small numbers
• Azoospermia: complete absence of spermatozoa in the ejaculate

Treatment of male infertility

Most causes can be resolved medically or surgically — from varicocele repair to antibiotic treatment of prostatitis or urogenital infection, to hormone therapy in hypogonadism. In the most severe cases of absent or extremely reduced sperm production (severe oligozoospermia, cryptozoospermia, azoospermia), once described as male sterility, it is now possible to retrieve spermatozoa directly from the testis or the epididymis and use them in assisted fertilisation.

Sperm retrieval techniques

• TEFNA: percutaneous fine-needle aspiration of sperm from the testis; an outpatient procedure under local anaesthesia lasting a few minutes
• MESA: microsurgical sperm aspiration from the epididymis
• TESE: surgical sperm extraction from the testis, performed as one-day surgery
• Micro-TESE: microsurgical extraction from the testis under an operating microscope, the most effective technique in azoospermia

Retrieved sperm can be cryopreserved for later use in assisted reproductive technology (ART):

• IVF-ET: in vitro fertilisation with embryo transfer
• ICSI: intracytoplasmic injection of a single selected spermatozoon into the oocyte

Prevention: why it starts in adolescence

Many causes of male infertility develop during adolescence and remain silent for years. With the end of compulsory military service in Italy, the only systematic andrological screening of young men disappeared. An andrological examination in adolescence allows early detection of conditions such as varicocele and cryptorchidism which, if left undiagnosed, can permanently compromise future fertility. Lifestyle, body weight, smoking and alcohol also have a direct and measurable impact on semen quality.

Frequently asked questions about male infertility

After how long is a couple considered infertile?

When pregnancy is not achieved after 12–24 months of regular unprotected intercourse. If the female partner is over 35, assessment is usually recommended after six months. Both partners should be investigated at the same time.

Can male infertility be treated?

In most cases, yes. Many causes — varicocele, infections, hormonal imbalance — respond to medical or surgical treatment. Even when no sperm is found in the ejaculate, spermatozoa can often be retrieved directly from the testis using microsurgical techniques and used for assisted fertilisation.

What is the most common cause of male infertility?

Varicocele, an abnormal dilatation of the veins around the testis. It is found in around 40% of infertile men and is in most cases surgically correctable, with possible improvement in semen parameters.

What is the difference between infertility and sterility?

Infertility describes a difficulty in conceiving that is, in most cases, treatable. Sterility was the term historically used for the absolute inability to procreate; today, thanks to sperm retrieval techniques and assisted reproduction, many of those situations still carry a realistic prospect of fatherhood.

What does a semen analysis measure?

The concentration, motility and morphology of spermatozoa in the seminal fluid. It is the first and central test in the assessment of male fertility and should be performed according to World Health Organization reference criteria.

Are you having difficulty conceiving, or would you like your fertility assessed? Ask Prof. Natali for a consultation or book an appointment at his practices in Florence and Empoli, Italy.

The information on this page is provided for general educational purposes and does not replace a medical examination, which remains the only diagnostic tool for correct and effective treatment.