From the Guidelines
Decreased ejaculate volume can occur due to several factors, including distal male genital tract obstruction, which is suspected when the ejaculate volume is low, as stated in the 2024 AUA/ASRM guideline 1.
Possible Causes of Decreased Ejaculate Volume
- Distal male genital tract obstruction, such as congenital bilateral absence of the vas deferens (CBAVD) or ejaculatory duct obstruction (EDO), can lead to low ejaculate volume (<1.4 mL) with acidic semen (pH <7.0) 1.
- Retrograde ejaculation, where semen enters the bladder instead of exiting through the penis, can also cause decreased ejaculate volume.
- Medical conditions like prostate surgery, diabetes, or hormonal imbalances can significantly impact ejaculate production.
- Lifestyle factors, including dehydration, frequent ejaculation without adequate recovery time, and substance use (alcohol, tobacco, marijuana), may temporarily reduce semen volume.
Diagnosis and Evaluation
- A low volume, acidic pH, azoospermic ejaculate is typically indicative of distal obstruction in the genital tract 1.
- Clinicians should be suspicious of distal male genital tract obstruction when the ejaculate volume is low 1.
- Scrotal ultrasound and transrectal ultrasonography (TRUS) or pelvic MRI may be used to evaluate the anatomy of the primary organs/structures involved in ejaculation, including the prostate, seminal vesicles, vasal ampulla, and ejaculatory ducts 1.
Management and Treatment
- Staying well-hydrated, allowing recovery time between ejaculations (24-72 hours), reducing substance use, and consulting a healthcare provider about medication adjustments might help address decreased ejaculate volume.
- If the decrease is sudden or concerning, medical evaluation is recommended to rule out underlying conditions, especially if accompanied by pain, difficulty urinating, or other symptoms.
- Treatment of underlying conditions, such as distal male genital tract obstruction, may improve ejaculate volume and fertility outcomes 1.
From the FDA Drug Label
Treatment with finasteride tablets for 24 weeks to evaluate semen parameters in healthy male volunteers revealed no clinically meaningful effects on sperm concentration, mobility, morphology, or pH. A 0.6 mL (22. 1%) median decrease in ejaculate volume with a concomitant reduction in total sperm per ejaculate was observed. These parameters remained within the normal range and were reversible upon discontinuation of therapy with an average time to return to baseline of 84 weeks [see Warnings and Precautions (5. 5)]. There have been postmarketing reports of male infertility and/or poor seminal quality; normalization or improvement of seminal quality has been reported after discontinuation of finasteride [see Adverse Reactions (6.2)].
The reason for decrease in ejaculate volume is due to treatment with finasteride tablets. The exact mechanism is not specified, but it is known that finasteride causes a median decrease of 0.6 mL (22.1%) in ejaculate volume. This effect is reversible upon discontinuation of therapy, with an average time to return to baseline of 84 weeks 2.
- Key points:
- Finasteride tablets cause a decrease in ejaculate volume
- The decrease is reversible upon discontinuation of therapy
- The exact mechanism is not specified
- Postmarketing reports also indicate that finasteride may cause male infertility and/or poor seminal quality, which can be improved or normalized after discontinuation of finasteride 2.
From the Research
Possible Causes of Ejaculate Decrease
- Hormonal changes: Some studies suggest that hormonal imbalances, particularly those related to testosterone and dihydrotestosterone, may contribute to ejaculate decrease 3, 4.
- Medications: Certain medications, such as finasteride, which is used to treat hair loss and benign prostatic enlargement, have been linked to ejaculate decrease and other sexual dysfunctions 3, 5.
- Age and health status: As men age, their semen volume and quality may decrease due to various factors, including hormonal changes, lifestyle factors, and underlying health conditions 4.
- Other factors: Other potential causes of ejaculate decrease may include stress, anxiety, and certain medical conditions, although more research is needed to fully understand these relationships.
Relationship Between Testosterone and Ejaculate
- Some studies have found no significant association between serum testosterone levels and ejaculate volume or quality 4.
- However, other research suggests that hormonal imbalances, including those related to testosterone, may contribute to ejaculate decrease and other sexual dysfunctions 3, 5.
Additional Considerations
- The current evidence does not provide a clear explanation for the decrease in ejaculate volume, and more research is needed to fully understand this issue.
- It is essential to consult with a healthcare professional to determine the underlying cause of ejaculate decrease and develop an effective treatment plan.