Male Factor Infertility
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Direct answer
Male factor infertility is reduced fertility caused by defective sperm production, sperm function or sperm delivery, and it contributes to a large share of couples who cannot conceive. Semen analysis is the first investigation. A clinical varicocele is the commonest correctable cause, while severe oligozoospermia or azoospermia calls for hormone tests, karyotype and Y chromosome microdeletion screening.
What you must remember
- Commonest correctable cause: Varicocele, mostly left-sided, because the left testicular vein drains at a right angle into the left renal vein.
- WHO 2021 reference values: The fifth centile lower limits are sperm concentration 16 million per mL, total motility 42 percent, progressive motility 30 percent and normal morphology 4 percent.
- Severe oligozoospermia: A count below 5 million per mL is the usual threshold for ICSI and for Y microdeletion testing.
- Obstructive azoospermia: Normal FSH, normal testicular volume and preserved sperm production in the testis, with a blockage along the tract.
- Non-obstructive azoospermia: Raised FSH and small firm testes, pointing to germinal failure.
- AZFc deletion: The most common Y microdeletion. AZFa and AZFb deletions usually mean no sperm can be retrieved.
- CBAVD: Congenital bilateral absence of the vas deferens is linked to CFTR mutations, so the female partner also needs CFTR carrier screening.
A stepwise male infertility work-up
Vignettes usually supply a semen report, a scrotal examination and a hormone panel, and the sequence below answers most of them.
- Repeat the semen analysis: Sperm counts vary between ejaculates, so a single abnormal result is repeated after several weeks, with two to seven days of abstinence before each sample.
- Examine the scrotum: Palpate for a varicocele in the standing position and measure testicular volume with an orchidometer, since small firm testes suggest germinal failure.
- Measure the hormones: Check FSH, LH, total testosterone, prolactin and TSH. A raised FSH signals primary testicular failure, while low FSH and LH with low testosterone signals hypogonadotropic hypogonadism, which responds to gonadotropin therapy.
- Send karyotype and Y microdeletion tests: Order these for azoospermia or severe oligozoospermia. Klinefelter syndrome (47,XXY) is the commonest chromosomal cause, and counselling matters because sons inherit an AZFc deletion.
- Image the tract: Scrotal and transrectal ultrasound help identify obstruction such as ejaculatory duct blockage or an absent vas deferens.
- Choose the treatment: Varicocelectomy suits a clinical varicocele with abnormal semen, while ICSI with ejaculated or retrieved sperm suits severe male factor.
Where the exam tries to catch you
A vignette often offers a tempting shortcut, and the correct option depends on the semen and hormone pattern.
- Trap: Choosing IUI for a man with a count of 2 million per mL. Correct: Severe male factor needs ICSI, because IUI cannot overcome very low counts or poor progressive motility.
- Trap: Repairing every palpable varicocele. Correct: Varicocelectomy is reserved for clinical varicocele with abnormal semen parameters, not for an incidental finding on a normal semen analysis.
- Trap: Calling azoospermia untreatable. Correct: Obstructive azoospermia is managed by sperm retrieval with ICSI, and micro-TESE can still find sperm in selected non-obstructive cases.
Frequently asked questions
Which investigation is the first step in male infertility?
Semen analysis is the first investigation in male infertility. It should be repeated after several weeks because sperm parameters vary between ejaculates, and results are compared with WHO 2021 lower reference values.
Which Y microdeletion region usually predicts absent sperm on retrieval?
Deletions of the AZFa and AZFb regions are generally associated with azoospermia and a very poor chance of retrieving sperm. The AZFc deletion is the commonest, and sperm may still be retrieved from some men who carry it.
What is the commonest correctable cause of male infertility?
A clinical varicocele is the commonest correctable cause of male infertility, most often on the left side. Repair is considered when the varicocele is clinically palpable and the semen analysis shows abnormal parameters, with the couple's overall fertility status also taken into account.
Why is FSH measured in azoospermia?
FSH distinguishes obstructive from non-obstructive azoospermia. A raised FSH with small testes suggests germinal failure, whereas normal FSH and testicular volume suggest an obstruction such as congenital bilateral absence of the vas deferens.
Do all men with a varicocele need surgery?
No, not all men with a varicocele need surgery. Repair is considered for a clinical varicocele with abnormal semen parameters, and a normal semen analysis alone is not an indication.