Semen volume measures the total amount of fluid ejaculated per sample in millilitres. Semen is produced by multiple accessory glands: the seminal vesicles contribute about 65-70% of volume, the prostate gland contributes about 25-30%, and the bulbourethral glands (Cowper's glands) contribute a small fraction. The testes and epididymis contribute the sperm cells but very little volume.
The WHO 2021 lower reference limit for semen volume is 1.4 mL. Very low volume (hypospermia, below 1.4 mL) can indicate ejaculatory dysfunction, retrograde ejaculation, obstruction of the ejaculatory ducts, or hormonal hypogonadism. Very high volume can dilute sperm concentration. Volume directly affects total sperm count per ejaculate.
FAQs
Does semen volume affect fertility?
Yes, indirectly. Semen volume contributes to total sperm count per ejaculate. Very low volume (hypospermia) reduces the total number of sperm delivered. The volume also provides an environment of seminal fluid proteins, fructose (energy for sperm), and protective factors that support sperm survival in the female reproductive tract.
What is retrograde ejaculation?
Retrograde ejaculation occurs when semen enters the bladder instead of exiting through the urethra during orgasm. It causes very low or absent semen volume with normal or low sensation of orgasm. It is common in men with diabetes, after prostate surgery (TURP), and with some medications (tamsulosin). Sperm can be retrieved from urine for fertility treatment.
Does abstinence period affect semen volume?
Yes. 2-7 days of abstinence is recommended for standardised semen analysis. Shorter abstinence reduces volume; longer periods increase volume beyond 7 days.
Can testosterone therapy reduce semen volume?
Yes. Exogenous testosterone suppresses LH and FSH, reducing testicular function and accessory gland secretions. Men on testosterone therapy wishing to preserve fertility should use hCG alongside or instead of testosterone.
