Low Sperm Count: What Causes Male Infertility and the 5-Step Evaluation Urologists Use

Low sperm count (oligozoospermia) affects up to 15% of couples trying to conceive. Defined as fewer than 15 million sperm per milliliter of ejaculate, it can lower the chance of fertilization but doesn't mean pregnancy is impossible. Understanding what causes low sperm count and how urologists evaluate it can help you take control of your reproductive health.

What Causes Low Sperm Count?

Male infertility has many potential contributors. Often, a combination of factors leads to reduced sperm production or function.

1. Medical Conditions

• Varicocele (enlarged veins in the scrotum)
• Infections (orchitis, epididymitis, prostatitis)
• Hormonal imbalances (low testosterone, pituitary disorders)
• Genetic disorders (Klinefelter syndrome, Y-chromosome microdeletions)
• Undescended testicles (cryptorchidism)
• Testicular injury or surgery
• Certain medications (chemotherapy, testosterone supplementation, some antifungals)

2. Lifestyle Factors

• High body temperature (frequent hot baths, saunas, tight underwear)
• Smoking tobacco or marijuana
• Excessive alcohol intake
• Recreational drug use (opioids, anabolic steroids)
• Chronic stress
• Poor diet and obesity
• Lack of exercise or excessive intense exercise

3. Environmental Exposures

• Pesticides, herbicides and heavy metals (lead, cadmium)
• Radiation and industrial chemicals
• Air pollution

4. Unknown Causes

In up to 30% of cases, no clear cause is found despite thorough testing (idiopathic infertility).

5-Step Evaluation Urologists Use

When you first see a urologist for fertility concerns, they'll typically follow a systematic, five-step approach:

1. Detailed Medical & Sexual History

• Review health history: childhood illnesses, surgeries, infections
• Discuss medications and supplements
• Ask about sexual development (puberty timing, libido)
• Evaluate lifestyle habits (smoking, alcohol, heat exposure)

2. Physical Examination

• Inspect and palpate testes for size, consistency, and presence of varicoceles
• Check penis and prostate (via digital rectal exam)
• Assess secondary sexual characteristics (body hair, muscle mass)
• Look for signs of hormonal disorders (gynecomastia, low muscle tone)

3. Semen Analysis

• Measures volume, sperm concentration, motility and morphology
• First sample after 2–7 days of abstinence; repeat test to confirm results
• May include tests for sperm vitality and round cell count

Key parameters:

• Sperm count: normal ≥15 million/mL
• Motility: normal ≥40% moving sperm
• Morphology: normal ≥4% of sperm with ideal shape

4. Hormonal Testing

• Follicle-stimulating hormone (FSH): high levels may indicate testicular failure
• Luteinizing hormone (LH) and testosterone: low levels suggest pituitary or testicular issues
• Prolactin and estradiol: to rule out pituitary tumors or hormone imbalances

5. Imaging & Specialized Tests

• Scrotal ultrasound: detects varicoceles, blockages, masses
• Transrectal ultrasound (TRUS): evaluates ejaculatory ducts and seminal vesicles
• Genetic tests: karyotype analysis, Y-chromosome microdeletions, CFTR gene in cases of absent vas deferens
• Post-ejaculatory urine analysis: checks for sperm in urine (retrograde ejaculation)
• Antisperm antibody testing: evaluates immune-related sperm damage
• Testicular biopsy (rarely): distinguishes between sperm production vs. blockage

Managing Low Sperm Count

Treatment depends on the underlying cause. Options include:

• Varicocele repair (surgical or radiologic)
• Antibiotics for infections
• Hormone therapy (clomiphene, hCG)
• Medication adjustments (switching off testosterone supplements)
• Assisted reproductive techniques (IUI, IVF with ICSI)
• Lifestyle modifications (quit smoking, reduce alcohol, maintain healthy weight)

Even small improvements in count, motility or morphology can boost natural fertility or success with assisted methods.

Steps You Can Take Now

• Maintain a healthy weight and balanced diet
• Choose loose-fitting underwear and avoid excessive heat
• Limit alcohol, quit smoking and avoid recreational drugs
• Reduce exposure to toxins (wear protective gear if needed)
• Manage stress with regular exercise and relaxation techniques

If you're concerned about symptoms like erectile dysfunction, low libido or scrotal pain, use this free AI-powered Male Infertility symptom checker to get personalized insights and understand whether you should seek medical evaluation.

When to Talk to a Doctor

Low sperm count rarely threatens your life, but some underlying issues—like infections or hormonal disorders—can have broader health implications. Always speak to a doctor if you experience:

• Sudden testicular pain or swelling
• Signs of hormonal imbalance (fatigue, breast tenderness, hair loss)
• Symptoms of infection (fever, painful urination)

Early evaluation and treatment not only improve fertility prospects but also help safeguard your overall health.