Treatment of Low Semen Volume

Initial Diagnostic Workup

• The primary goal for low semen volume (<1.4 mL) is to identify and treat the underlying cause, according to the American Urological Association, rather than treating the symptom itself 1
• Palpation for vas deferens bilaterally is necessary to rule out congenital bilateral absence of vas deferens (CBAVD), which can be diagnosed by physical examination alone, as recommended by the American Urological Association 1, 2
• Assessment for palpable varicoceles is crucial, as treatment of clinical (palpable) varicoceles improves semen parameters and fertility, while non-palpable varicoceles should not be treated, according to the American Urological Association 1
• Evaluation of testicular size and consistency is important, as normal-sized testes suggest obstruction while atrophic testes indicate spermatogenic failure, as noted by the American Urological Association 2
• A digital rectal examination should be performed to assess prostate size and consistency, as recommended by the American Urological Association 2

Critical Laboratory Tests

• Checking semen pH is necessary, as acidic semen (pH <7.0) with low volume strongly suggests ejaculatory duct obstruction or CBAVD, according to the American Urological Association 1
• Measuring serum testosterone and FSH is crucial, as low testosterone with low/normal FSH indicates hypogonadotropic hypogonadism, while elevated FSH (>7.6 IU/L) suggests primary testicular failure, as noted by the American Urological Association 2
• Post-ejaculatory urinalysis should be performed when volume <1 mL (except in bilateral vasal agenesis or hypogonadism) to diagnose retrograde ejaculation, as recommended by the American Urological Association 2

Imaging When Indicated

• TRUS or pelvic MRI is indicated for suspected ejaculatory duct obstruction when semen is acidic, volume <1.4 mL, with azoospermia or severe oligospermia with very low motility, normal testosterone, and palpable vas deferens, according to the American Urological Association 1
• Routine scrotal ultrasound for varicocele diagnosis should be avoided, as only palpable varicoceles warrant treatment, as recommended by the American Urological Association 1

Treatment Based on Etiology

• Transurethral resection of ejaculatory ducts (TURED) is the definitive treatment for confirmed EDO on TRUS or MRI showing dilated seminal vesicles and ejaculatory ducts, according to the American Urological Association 1
• For congenital bilateral absence of vas deferens, no medical or surgical treatment restores ejaculatory volume, and proceeding directly to sperm retrieval (TESE/MESA) with ICSI is recommended for fertility, as noted by the American Urological Association 1, 2
• CFTR gene testing for the female partner is mandatory before proceeding with assisted reproduction, as recommended by the American Urological Association 2
• For clinical varicocele, varicocelectomy improves semen parameters and may restore sperm in ejaculate for men with azoospermia, particularly those with hypospermatogenesis on histology, according to the American Urological Association 1, 3
• Treatment is indicated for palpable varicoceles with abnormal semen parameters, as recommended by the American Urological Association 1, 3
• Subclinical (non-palpable) varicoceles should not be treated, as this does not improve semen parameters or fertility rates, according to the American Urological Association 1, 3

Genetic Considerations Before Treatment

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

Common Pitfalls to Avoid

• TRUS or pelvic MRI should not be performed as part of the initial evaluation—reserve for cases with clear clinical suspicion of EDO (low volume, acidic, azoospermic semen with normal testosterone and palpable vas), as recommended by the American Urological Association 1
• Ultrasound should not be used to hunt for subclinical varicoceles—only palpable varicoceles benefit from treatment, according to the American Urological Association 1, 3
• Genetic testing should not be delayed—results impact counseling and treatment decisions before proceeding with assisted reproduction, as recommended by the American Urological Association 2

Evaluation and Management of Reduced Ejaculate Volume

Initial Evaluation

• Men presenting with ejaculate volume < 1.4 mL should undergo a systematic work‑up to identify the underlying cause (e.g., ejaculatory duct obstruction, congenital bilateral absence of the vas deferens, or retrograde ejaculation) before initiating treatment. 4

Imaging Recommendations

Targeted Imaging for Suspected Ejaculatory Duct Obstruction

• Transrectal ultrasound (TRUS) or pelvic magnetic resonance imaging (MRI) is indicated only when semen is acidic, volume < 1.4 mL, azoospermia or severe oligospermia with markedly reduced motility is present, serum testosterone is normal, and the vas deferens are palpable. 4
• Routine TRUS or pelvic MRI should not be performed as part of the initial evaluation of all low‑volume cases; it is reserved for patients meeting the high‑suspicion criteria above. 4
• Pelvic MRI can visualize dilated seminal vesicles, enlarged ejaculatory ducts, and characterize prostate or midline cystic lesions that may cause obstruction. 4

Scrotal Ultrasound

• Routine scrotal ultrasound for varicocele assessment is not recommended; imaging is only useful when a palpable varicocele is present, a testicular mass is suspected, or precise testicular volume measurement is required. 4

Etiology‑Specific Diagnostic Criteria

Ejaculatory Duct Obstruction (EDO)

• EDO should be suspected when semen is acidic (pH < 7.0), ejaculate volume < 1.4 mL, azoospermia or severe oligospermia with very low motility is observed, serum testosterone is normal, and the vas deferens are palpable. 4

Subclinical Varicocele

• Non‑palpable (subclinical) varicoceles do not require treatment, as intervention does not improve semen parameters or fertility outcomes. 4

Retrograde Ejaculation

• Diagnosis is confirmed by detecting sperm in post‑ejaculatory urine when ejaculate volume is < 1 mL. 4

Genetic Testing Prior to Assisted Reproduction

• Karyotype analysis is required for men with azoospermia or severe oligospermia (sperm concentration < 5 million/mL). 4
• Y‑chromosome microdeletion testing is mandatory for azoospermia or very low sperm concentration ( < 1 million/mL). 4

Medication‑Related Effects

• Finasteride 5 mg daily reduces ejaculate volume by roughly 25 %; a 1 mg daily dose produces a negligible median decrease (~0.03 mL) that is not clinically significant. 4

Critical Pitfalls to Avoid

• Do not pursue imaging for subclinical varicoceles with ultrasound; only palpable varicoceles benefit from surgical correction. 4
• Do not employ TRUS or pelvic MRI as a routine component of the initial low‑volume work‑up; reserve these studies for cases with clear clinical suspicion of ejaculatory duct obstruction. 4

Imaging Recommendations for Suspected Ejaculatory Duct Obstruction

Role of Transrectal Ultrasound (TRUS) and Pelvic MRI

• The American College of Radiology (ACR) recommends that transrectal ultrasound be used as the first‑line imaging modality for evaluating suspected ejaculatory duct obstruction, with a performance rating of 8/9; pelvic MRI should be reserved for cases where TRUS is negative or inconclusive. 5

• According to the ACR, pelvic MRI is especially valuable when detailed anatomic information is required for surgical planning (e.g., transurethral resection of the ejaculatory ducts) or when TRUS cannot adequately visualize the ejaculatory ducts because of patient body habitus or technical limitations. 5