What are the causes and treatments for reduced arousal and low semen volume?

Reduced Arousal and Reduced Semen Volume: Causes and Treatment

Begin by identifying the underlying cause through targeted physical examination and laboratory testing, as reduced semen volume has specific etiologies requiring distinct treatments, while reduced arousal often reflects hormonal, psychological, or medication-related factors that must be addressed separately.

Initial Diagnostic Evaluation

Physical Examination Priorities

• Palpate bilaterally for vas deferens to rule out congenital bilateral absence of vas deferens (CBAVD), which can be diagnosed by physical examination alone 1
• Assess testicular size and consistency: normal-sized testes suggest obstruction while atrophic testes indicate spermatogenic failure 1
• Examine for palpable varicoceles, as treatment of clinical (palpable) varicoceles improves semen parameters, whereas non-palpable varicoceles should not be treated 1
• Perform digital rectal examination to assess prostate size and consistency 1

Critical Laboratory Tests

• Check semen pH: acidic semen (pH <7.0) with low volume strongly suggests ejaculatory duct obstruction or CBAVD 1
• Measure serum testosterone and FSH: low testosterone with low/normal FSH indicates hypogonadotropic hypogonadism, while elevated FSH (>7.6 IU/L) suggests primary testicular failure 1
• Perform post-ejaculatory urinalysis when volume <1 mL (except in bilateral vasal agenesis or hypogonadism) to diagnose retrograde ejaculation 1
• Check morning testosterone levels in men with reduced arousal, as testosterone has a primary role in controlling and coordinating male sexual desire and arousal 2
• Measure prolactin levels, as hyperprolactinemia is associated with low desire which can be successfully corrected by appropriate treatments 2

Specific Causes of Reduced Semen Volume

Medication-Related Causes

• Finasteride 5 mg/day is associated with reduced semen volume, but 1 mg/day data are inconclusive 3
• Alcohol consumption results in slightly lower semen volume and slightly poorer sperm morphology 3

Lifestyle and Environmental Factors

• Occupational exposure to oil and natural gas extraction reduces semen volume and sperm motility 3
• Poor diet results in reduced fertility 3
• Smoking is associated with slightly reduced fertility 3
• Anabolic steroid use is associated with reduced fertility and should be discontinued 3

Structural Causes

• Ejaculatory duct obstruction (EDO) presents with acidic, azoospermic semen with volume <1.4 mL, normal serum testosterone, and palpable vas deferens 3
• Congenital bilateral absence of vas deferens requires no medical or surgical treatment to restore ejaculatory volume; proceed directly to sperm retrieval (TESE/MESA) with ICSI for fertility 1

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 1
• Do not routinely order TRUS or pelvic MRI as part of initial evaluation—reserve for cases with clear clinical suspicion of EDO 1
• Avoid routine scrotal ultrasound for varicocele diagnosis, as only palpable varicoceles warrant treatment 1

Treatment Based on Etiology

For 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 1

For Clinical Varicocele

• Varicocelectomy improves semen parameters and may restore sperm in ejaculate for men with azoospermia, particularly those with hypospermatogenesis on histology 1
• Treatment is indicated for palpable varicoceles with abnormal semen parameters 1
• Subclinical (non-palpable) varicoceles should not be treated, as this does not improve semen parameters or fertility rates 1

For Reduced Arousal

Hormonal Treatment

• Testosterone replacement therapy for hypogonadal individuals can improve low desire and erectile dysfunction, according to meta-analysis 2
• Normalize serum testosterone levels in patients with delayed ejaculation and testosterone deficiency 3
• Treat hyperprolactinemia appropriately, as it is associated with low desire which can be successfully corrected 2

Medication Management

• Review and modify medications that may contribute to delayed ejaculation or reduced arousal 3
• Consider replacement, dose adjustment, or staged cessation of medications contributing to sexual dysfunction 3

Behavioral and Psychological Interventions

• Refer to a mental health professional with expertise in sexual health for men with lifelong or acquired delayed ejaculation 3
• Advise modifying sexual positions or practices to increase arousal, as behavioral interventions are a low-risk option that may help enhance arousal and trigger orgasmic response 3
• Incorporate alternative sexual practices, scripts, and/or sexual enhancement devices to increase physical and psychological arousal 3

Pharmacotherapy for Delayed Ejaculation

When behavioral interventions are insufficient, consider the following pharmacotherapies 3:

• Oxytocin: 24 IU intranasal/sublingual during sex
• Pseudoephedrine: 60-120 mg (120-150 minutes prior to sex)
• Ephedrine: 15-60 mg (1 hour prior to sex)
• Midodrine: 5-40 mg daily (30-120 minutes prior to sex)
• Bethanecol: 20 mg daily
• Yohimbine: 5.4 mg three times daily
• Cabergoline: 0.25-2 mg twice weekly
• Imipramine: 25-75 mg daily

For Comorbid Erectile Dysfunction

• Treat men who have delayed ejaculation and comorbid erectile dysfunction according to AUA Guidelines on Erectile Dysfunction 3
• Define the chronology of ED and delayed ejaculation relationship, as when delayed ejaculation precedes the onset of ED, the focus should be on the delayed ejaculation 3

Genetic Testing Before Assisted Reproduction

• Karyotype testing is mandatory for azoospermia or severe oligospermia (<5 million/mL) 1
• Y-chromosome microdeletion analysis is required for azoospermia or sperm concentration <1 million/mL 1
• CFTR gene testing for the female partner is mandatory before proceeding with assisted reproduction in cases of CBAVD 1
• Genetic counseling should precede ICSI, as genetic abnormalities may be transmitted to offspring 1

Critical Pitfalls to Avoid

• Never initiate testosterone replacement therapy in men desiring fertility, as it suppresses spermatogenesis 4
• Do not use ultrasound to hunt for subclinical varicoceles—only palpable varicoceles benefit from treatment 1
• Do not delay genetic testing—results impact counseling and treatment decisions before proceeding with assisted reproduction 1
• Stress is associated with reduced sperm progressive motility but has no association with semen volume, so do not attribute low semen volume to stress alone 3