The male ejaculation or discharge of semen at the time of sexual intercourse sometimes goes awry and there could be a lack of ejaculation. Instead of travelling from the sperm storage sac (seminal vesicle) in the groin, into the penis and out through the urethra, the ejaculate goes backwards into the urinary bladder.
Causes include prostate surgery or disease, injury to the pelvis or the spinal cord, diabetes, or a tumour of the spinal cord. It may also be due to psychological stress, a stroke, tumour or cancer in the brain, compression to or damage of the nerves in the pelvis, Parkinson’s disease, or to an abnormality the individual was born with (when it will usually become evident soon after puberty).
Sometimes it may be a side effect of medications such as those used to treat high blood pressure, psychiatric conditions, and diuretics (which remove excess fluid from the body). Often no cause can be found.