Male Factor Infertility

Causes of Male Infertility

Male infertility has multiple causes, often overlapping. The primary categories are:

In approximately 30-40% of male infertility cases, no identifiable cause is found. This is classified as idiopathic male infertility and remains one of the most challenging diagnostic gaps in reproductive medicine.

Sperm Testing

The cornerstone of male fertility evaluation is the semen analysis. This test measures three primary parameters:

• • Concentration, the number of sperm per milliliter of ejaculate. WHO 2021 lower reference limit: 16 million/mL.
• • Motility, the percentage of sperm that are moving, and specifically progressively motile (swimming forward). WHO 2021 lower reference limit: 42% total motility.
• • Morphology, the percentage of sperm with normal head, midpiece, and tail structure. WHO 2021 lower reference limit: 4% normal forms using strict (Kruger) criteria.

Semen analysis also measures volume, pH, and liquefaction time. However, a standard semen analysis does not assess DNA integrity, oxidative stress markers, or functional capacity of the sperm. A "normal" semen analysis does not guarantee normal fertility.

If the first semen analysis is abnormal, repeat testing is recommended after 2-3 months (one full spermatogenesis cycle). Single abnormal results may reflect temporary conditions such as illness, fever, or medication use. Persistent abnormalities require further investigation.

Advanced testing includes hormonal panels (FSH, LH, testosterone, prolactin), genetic karyotype, Y-chromosome microdeletion screening, scrotal ultrasound, and post-ejaculation urinalysis for retrograde ejaculation.

DNA Fragmentation

Sperm DNA fragmentation (SDF) refers to breaks or damage in the DNA strands within sperm cells. It is increasingly recognized as a critical but under-tested parameter in male fertility evaluation.

High DNA fragmentation rates are associated with:

• • Reduced fertilization rates
• • Poor embryo development and increased arrest
• • Lower implantation rates
• • Higher miscarriage rates, particularly recurrent pregnancy loss
• • Poorer IVF/ICSI outcomes even with "normal" semen parameters

SDF is not detected by standard semen analysis. It requires specific testing: TUNEL, SCD (Halosperm), SCSA, or Comet assay. A DNA fragmentation index (DFI) above 30% is generally considered elevated, though thresholds vary by test methodology.

Causes of elevated SDF include oxidative stress, age, smoking, obesity, varicocele, infection, fever, environmental toxins, and prolonged abstinence. Some of these are modifiable. Shorter ejaculatory abstinence intervals (24-48 hours rather than 3-5 days) can reduce SDF in subsequent samples.

When SDF is elevated, treatment options include lifestyle modification, antioxidant supplementation (evidence is low-certainty), varicocele repair, testicular sperm extraction (TESE) to bypass epididymal oxidative damage, and shorter abstinence protocols before IVF/ICSI.

IVF and ICSI Solutions

Intracytoplasmic sperm injection (ICSI) is the primary IVF technique used when male factor infertility is present. Instead of allowing sperm to fertilize eggs in a dish (conventional IVF), ICSI involves directly injecting a single sperm into each mature egg.

ICSI is recommended when:

• • Sperm count is very low (severe oligozoospermia)
• • Motility is severely impaired (asthenozoospermia)
• • Morphology is significantly abnormal (teratozoospermia)
• • Sperm is surgically retrieved (TESE, micro-TESE, MESA)
• • Previous IVF cycles showed poor or zero fertilization with conventional insemination
• • Frozen sperm is being used (count and motility often reduced post-thaw)

For men with obstructive azoospermia (no sperm in ejaculate due to blockage), surgical sperm retrieval techniques provide viable sperm directly from the epididymis (MESA) or testicular tissue (TESE/micro-TESE). These sperm are then used for ICSI.

For men with non-obstructive azoospermia (production failure), micro-TESE may recover small pockets of sperm production within the testicular tissue. Success rates for sperm retrieval in non-obstructive azoospermia range from 40-60% depending on the underlying cause and surgical technique.

When no viable sperm can be obtained, donor sperm is the remaining biological pathway. This is a difficult conversation but an important one to have early in the diagnostic process.

The Age Factor

Unlike female fertility, male fertility does not have a hard biological cutoff. Sperm production continues throughout life. However, the quality of that production declines with age.

Advanced paternal age (generally defined as over 40-45) is associated with increased sperm DNA fragmentation, higher rates of de novo genetic mutations, modestly increased miscarriage rates, and small but measurable increases in certain developmental conditions in offspring.

The effects are less dramatic than maternal age but are biologically real and should be part of the informed consent conversation, particularly when both partners are over 40.