Unknown Aspermia Prevalence Cannot Be Determined
There is no reliable epidemiological data available to determine what percentage of men have aspermia (absence of ejaculate) without knowing it. The available evidence focuses on diagnosed cases of male infertility and azoospermia (absence of sperm in ejaculate), not aspermia specifically, and even for these conditions, population-level prevalence data for undiagnosed cases does not exist.
Why This Question Cannot Be Answered
Fundamental Data Limitations
Current evidence is insufficient to determine unbiased prevalence of male infertility in general populations, let alone specific conditions like aspermia 1
Studies of male infertility suffer from inherent selection bias—they only capture men who present for evaluation, missing those who remain undiagnosed 1
Not all couples experiencing infertility seek medical consultation, and among those who do, not all men undergo comprehensive evaluation 1
Aspermia-Specific Considerations
Aspermia (complete absence of ejaculate) is primarily caused by severe sexual dysfunction (71.7% of diagnosed aspermia cases), with other causes including retrograde ejaculation or ejaculatory duct obstruction 2
Men with aspermia would likely notice the absence of ejaculate during sexual activity, making truly "unknown" aspermia uncommon in sexually active men 2
In a large prospective study of 1,737 men with severe male factor infertility, only 46 cases (2.6%) had aspermia, and 100% of these cases had an identifiable cause 2
What We Do Know About Diagnosed Cases
Aspermia Prevalence in Infertility Populations
Among men presenting with severe male factor infertility (total sperm count ≤5 million/ml), aspermia represents approximately 2.6% of cases 2
The main identifiable cause is severe sexual dysfunction, which would typically be symptomatic and noticeable 2
Azoospermia (Different Condition)
Approximately 1% of all men in the general population have azoospermia (no sperm in ejaculate, but ejaculate is present) 3
Clinical Implications
Men who are sexually active and producing ejaculate would notice its absence, making aspermia a condition that is unlikely to remain undiagnosed in men attempting conception. The more relevant clinical question concerns azoospermia or oligozoospermia, where ejaculate is present but sperm are absent or reduced—conditions that can only be detected through semen analysis 5, 3.
Key Caveat
Population-based studies with consistent definitions and comparable study designs across different geographical regions are urgently needed to determine true prevalence of male reproductive disorders 1
Current evidence quality for male infertility epidemiology is rated as "very low" by WHO-supported guidelines 1