What are the causes and treatments of watery semen (hypospermia)?

Watery Semen: Causes and Management

Watery semen most commonly results from either frequent ejaculation causing temporary depletion of seminal fluid components, or from underlying pathology including retrograde ejaculation, ejaculatory duct obstruction, hypogonadism, or seminal vesicle/prostate dysfunction.

Understanding Normal vs. Abnormal Semen Consistency

• Normal semen initially coagulates after ejaculation and then liquefies within 15-30 minutes due to prostate-derived serine proteases 1
• Watery semen that lacks normal viscosity may indicate hypofunction of the prostate or seminal vesicles, which produce proteins essential for normal semen coagulation 2
• The condition differs from hyperviscous semen, which affects 12-29% of men and represents the opposite problem 2

Primary Causes to Evaluate

Low Ejaculate Volume (Hypospermia)

If semen volume is <1.5 mL with watery consistency, suspect ejaculatory duct obstruction or retrograde ejaculation as the primary cause 3

• Retrograde ejaculation has a prevalence of 40.5% among infertile patients with hypospermia 4
• Perform post-ejaculatory urinalysis when ejaculate volume is <1 mL to diagnose retrograde ejaculation by identifying sperm in urine 5
• Low volume with acidic semen (pH <7.0) suggests ejaculatory duct obstruction and warrants transrectal ultrasonography (TRUS) evaluation 3
• Congenital bilateral absence of vas deferens (CBAVD) presents with very low volume and should be assessed by palpating for vas deferens on physical examination 5

Seminal Gland Dysfunction

• Hypofunction of the prostate or seminal vesicles causes abnormal viscosity and watery appearance of seminal fluid 2
• Infection and high levels of seminal leukocytes (pyospermia) may result in altered semen consistency 2
• CFTR gene mutations can cause seminal vesicle and vas deferens abnormalities leading to hypospermia 6

Hormonal Causes

• Hypogonadism with low testosterone can reduce seminal vesicle and prostate secretions 5
• Men with retrograde ejaculation have significantly lower FSH, LH, and testosterone levels compared to those without retrograde ejaculation 4

Diagnostic Algorithm

Step 1: Confirm the Finding

• Obtain at least two semen analyses one month apart, with 2-3 days of abstinence before collection 5
• Measure ejaculate volume, pH, and assess viscosity 3

Step 2: Physical Examination

• Palpate for presence of vas deferens bilaterally to rule out CBAVD 5
• Assess testicular size and consistency - normal-sized testes suggest obstructive pathology while atrophic testes indicate primary testicular dysfunction 5
• Perform digital rectal examination to assess prostate 5

Step 3: Post-Ejaculatory Urinalysis

• Mandatory when ejaculate volume is <1 mL (except in bilateral vasal agenesis or hypogonadism) 5
• Presence of >10-15 sperm per high-power field in post-ejaculatory urine confirms retrograde ejaculation 4

Step 4: Hormonal Evaluation

• Measure serum testosterone and FSH as primary hormonal assessment 5
• Consider LH measurement as part of comprehensive evaluation 5

Step 5: Imaging When Indicated

• TRUS is indicated for azoospermic or severely oligospermic patients with palpable vas deferens and low ejaculate volume to evaluate for ejaculatory duct obstruction 5
• Renal ultrasonography is recommended for patients with vasal agenesis to evaluate for renal abnormalities 3

Step 6: Genetic Testing

• CFTR gene testing should be offered when CBAVD is suspected, as mutations are involved in many forms of cystic fibrosis 6
• Karyotype testing is recommended for patients with azoospermia or severe oligospermia (<5 million/mL) 5

Treatment Approaches

For Retrograde Ejaculation

• Medical therapy with sympathomimetics is first-line treatment 7
• Treatment increases seminal volume (from 1.2 to 1.5 mL) and mobile sperm count (from 47.2 to 62.5 million) 4
• Urinary sperm retrieval can be used for assisted reproduction if medical therapy fails 7

For Infection-Related Causes

• Antibiotics and anti-inflammatory agents are indicated when infection or pyospermia is identified 2
• Special stains are required to differentiate white blood cells from germ cells in semen 3

For Ejaculatory Duct Obstruction

• Bladder neck reconstruction may be considered in select cases 7
• Surgical sperm retrieval is an option for assisted reproductive technology 7

Critical Pitfalls to Avoid

• Do not prescribe testosterone replacement therapy if fertility is desired, as exogenous testosterone suppresses spermatogenesis and can worsen the condition 8, 5
• Do not assume watery semen alone indicates infertility - complete semen analysis with sperm count and motility assessment is essential 5
• Do not overlook CFTR testing in men with CBAVD, as this has implications for the patient's health and potential offspring 6
• Routine semen cultures have not been prospectively demonstrated to benefit infertile couples, so avoid unless pyospermia is present 3