Is low semen volume a problem for infertility?

Is Low Semen Volume a Problem for Infertility?

Yes, low semen volume (<1.5 mL) is a significant problem for infertility because it indicates underlying pathology requiring investigation and treatment, particularly ejaculatory duct obstruction or congenital bilateral absence of vas deferens, both of which directly impair fertility. 1

Clinical Significance of Low Semen Volume

Low semen volume is not merely a statistical abnormality—it serves as a critical diagnostic marker for specific, treatable causes of male infertility:

• Ejaculatory duct obstruction (EDO) presents with acidic semen (pH <7.0), volume <1.4 mL, and azoospermia or severe oligospermia with very low motility, normal testosterone, and palpable vas deferens 1, 2
• Congenital bilateral absence of vas deferens (CBAVD) can be diagnosed by physical examination alone and presents with low volume, acidic semen, and azoospermia 1, 3
• Retrograde ejaculation should be suspected when volume is <1 mL and confirmed with post-ejaculatory urinalysis showing sperm in urine 1

Impact on Fertility Outcomes

The relationship between low semen volume and fertility is complex and depends on the underlying cause:

• Paradoxically, isolated low semen volume (<1.5 mL) without other abnormalities was associated with HIGHER fecundability (FR 1.48,95% CI 1.05-2.08) in a prospective North American cohort study 4
• However, low semen volume combined with other abnormalities (particularly low total sperm count <39 million) significantly reduces fecundability (FR 0.58,95% CI 0.38-0.88) 4
• Men with low semen volume have higher mortality rates when combined with other semen abnormalities, suggesting it may be a marker of overall health 5

Diagnostic Algorithm for Low Semen Volume

When encountering semen volume <1.5 mL, follow this systematic approach:

Step 1: Confirm with Repeat Testing

• Obtain at least two semen analyses one month apart with 2-3 days abstinence before collection 1
• Ensure proper collection technique and transport at room/body temperature within one hour 1

Step 2: Physical Examination

• Palpate bilaterally for vas deferens—absence confirms CBAVD without need for further testing 2, 3
• Assess testicular size and consistency—normal-sized testes suggest obstruction while atrophic testes indicate spermatogenic failure 2, 6
• Examine for palpable varicoceles—only treat if palpable, as subclinical varicoceles do not benefit from treatment 1, 2
• Perform digital rectal examination to assess prostate size and consistency 1, 2

Step 3: Laboratory Evaluation

• Check semen pH—acidic semen (pH <7.0) with low volume strongly suggests EDO or CBAVD 1, 2
• Measure serum testosterone and FSH—low testosterone with low/normal FSH indicates hypogonadotropic hypogonadism; elevated FSH (>7.6 IU/L) suggests primary testicular failure 1, 2
• Perform post-ejaculatory urinalysis when volume <1 mL (except in bilateral vasal agenesis or hypogonadism) to diagnose retrograde ejaculation 1, 2

Step 4: Imaging When Indicated

• Reserve TRUS or pelvic MRI for suspected EDO only—specifically when semen is acidic, volume <1.4 mL, with azoospermia or severe oligospermia, normal testosterone, and palpable vas deferens 1, 2
• Do NOT routinely order TRUS or pelvic MRI as part of initial evaluation—this is a common pitfall 2, 3

Treatment Based on Etiology

Ejaculatory Duct Obstruction

• Transurethral resection of ejaculatory ducts (TURED) is the definitive treatment for confirmed EDO on TRUS or MRI showing dilated seminal vesicles and ejaculatory ducts 2, 3

Congenital Bilateral Absence of Vas Deferens

• No medical or surgical treatment restores ejaculatory volume—proceed directly to sperm retrieval (TESE/MESA) with ICSI for fertility 2, 3
• CFTR gene testing for the female partner is mandatory before proceeding with assisted reproduction 2, 3

Retrograde Ejaculation

• Consider pharmacotherapy with pseudoephedrine, ephedrine, midodrine, or imipramine 2
• Sperm can be retrieved from post-ejaculatory urine for assisted reproduction if medical management fails 7

Clinical Varicocele

• Varicocelectomy improves semen parameters and may restore sperm in ejaculate for men with azoospermia, particularly those with hypospermatogenesis on histology 2, 3
• Treatment is indicated for palpable varicoceles with abnormal semen parameters 2, 3

Genetic Testing Before Assisted Reproduction

When low semen volume is associated with azoospermia or severe oligospermia:

• Karyotype testing is mandatory for azoospermia or severe oligospermia (<5 million/mL) 2, 6
• Y-chromosome microdeletion analysis is required for azoospermia or sperm concentration <1 million/mL 2, 6
• Genetic counseling should precede ICSI, as genetic abnormalities may be transmitted to offspring 2, 3

Critical Pitfalls to Avoid

• Never initiate testosterone replacement therapy in men desiring fertility—it suppresses spermatogenesis 2
• Do not use ultrasound to hunt for subclinical varicoceles—only palpable varicoceles benefit from treatment 1, 2, 3
• Do not delay genetic testing—results impact counseling and treatment decisions before proceeding with assisted reproduction 2, 3
• Do not attribute low semen volume to stress alone—stress is associated with reduced sperm progressive motility but has no association with semen volume 1, 2

Modifiable Risk Factors

Several factors are associated with reduced semen volume and should be addressed:

• Finasteride 5 mg/day is associated with reduced semen volume (1 mg/day data are inconclusive) 1, 2
• Alcohol consumption results in slightly lower semen volume and slightly poorer sperm morphology 1, 2
• Occupational exposure to oil and natural gas extraction reduces semen volume and sperm motility 1, 2
• Anabolic steroid use is associated with reduced fertility and should be discontinued 1, 2