A semen analysis is a standardised evaluation of the ejaculate, assessing several key parameters. Concentration: the WHO 2021 reference value is at least 16 million sperm per millilitre. Motility: at least 42% motile sperm (categories A+B). Morphology: at least 4% normal forms by strict Kruger criteria. Total count in the ejaculate: at least 39 million.
The three main abnormalities: oligozoospermia (low count), asthenozoospermia (low motility), teratozoospermia (high proportion of abnormal forms). These often occur together — referred to as OAT syndrome. Azoospermia — the complete absence of sperm — is the most severe form.
An important caveat: a semen analysis is a snapshot of a single moment. Sperm quality varies considerably and is affected by illnesses over the preceding three months (the duration of spermatogenesis), stress, temperature and alcohol. One poor result is a reason to repeat the test in two to three months — not to panic.
Varicocele — enlargement of the veins in the spermatic cord — is the most commonly identified cause of male infertility, present in up to 40% of cases. It raises the temperature in the scrotum, disrupting spermatogenesis. It is surgically correctable, and in some cases sperm parameters improve after surgery.
Hormonal disorders: deficiency of FSH, LH or testosterone impairs sperm production. Hyperprolactinaemia, thyroid dysfunction — all affect spermatogenesis. Important: anabolic steroid use suppresses endogenous testosterone and can lead to azoospermia — often reversible after stopping, but not always.
Obstructive azoospermia: sperm are produced but cannot exit due to a blockage in the vas deferens. Causes include infections (chlamydia, gonorrhoea), surgery, and congenital absence of the vas deferens (in cystic fibrosis). In these cases, sperm are retrieved directly from the testis (biopsy) and used for ICSI.
Infections and inflammation: orchitis, epididymitis, mumps contracted in adulthood — all can leave permanent consequences for spermatogenesis. STIs (chlamydia, mycoplasma) reduce sperm motility.
Genetic factors: Y-chromosome microdeletions, Klinefelter syndrome (47,XXY) — causes of severe oligozoospermia or azoospermia. With certain mutations (AZFa, AZFb deletions), surgical sperm retrieval is not possible.
Lifestyle: smoking reduces sperm concentration and motility. Alcohol affects morphology. Obesity, through elevated oestrogen, disrupts hormonal balance. Overheating (hot baths, saunas, a laptop on the lap) temporarily reduces sperm quality — the testes function best at 2 to 4°C below body temperature.
A semen analysis is the starting point, not the full picture. If abnormalities are found, extended testing is indicated: MAR test (antisperm antibodies), sperm DNA fragmentation, hormonal profile (FSH, LH, testosterone, prolactin, TSH), genetic testing (karyotype, Y-chromosome deletions).
DNA fragmentation is a particularly important parameter absent from the basic semen analysis. High sperm DNA fragmentation reduces fertilisation rates and increases miscarriage risk — even when basic parameters are normal. Some couples with unexplained infertility or recurrent pregnancy loss find the answer here.
Scrotal ultrasound: visualises varicocele, testicular volume, epididymal structure. Small testicular volume (<15 ml) with azoospermia is a poor prognostic sign.
When a cause is identified, the cause is treated. Surgical correction of varicocele, antibiotics for infection, hormone therapy for hypogonadism, cessation of anabolic steroids with follow-up testing.
When no cause is found or treatment is not possible, assisted reproductive technology is used. ICSI (intracytoplasmic sperm injection) enables fertilisation even with extremely low counts — including with single sperm. In obstructive azoospermia, sperm are retrieved from the testis or epididymis (TESA, PESA, micro-TESE) and used for ICSI.
Antioxidant therapy: vitamin C, E, CoQ10, zinc, selenium — used in idiopathic sperm parameter reduction. Evidence is mixed, but some meta-analyses show modest improvements in motility and morphology after three to six months of use.
Male factor infertility is neither rare nor shameful. It is a medical question with understandable mechanisms and real solutions. A semen analysis is a simple, quick test that should be carried out at the same time as the female workup — not after it.
When abnormalities are found, a consultation with an andrologist or urologist-andrologist is essential. With severe impairment, a fertility specialist will assess the options for ICSI. When genetic factors are identified, genetic counselling is needed before any treatment.
Azoospermia — the complete absence of sperm in the ejaculate. May be obstructive (sperm are produced but cannot exit) or non-obstructive (impaired production).
Asthenozoospermia — sperm motility below the WHO reference value.
DNA fragmentation — the degree of damage to the genetic material within sperm. High fragmentation reduces the chances of successful fertilisation and pregnancy.
ICSI (intracytoplasmic sperm injection) — injection of a single sperm directly into an egg. The method of choice in severe male factor infertility.
Oligozoospermia — sperm concentration below the WHO reference value (less than 16 million/ml).
Spermatogenesis — the process of sperm formation, taking around 72 to 74 days (plus maturation). This is why illnesses or external factors appear in a semen analysis two to three months later.
Teratozoospermia — a high proportion of sperm with abnormal morphology (more than 96% by strict criteria).
Varicocele — enlargement of the veins in the spermatic cord. The most common surgically correctable cause of male infertility.
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