Some men make sperm, but cannot get them into their partner's vagina. This may be because:

• They cannot get an erection. To find out more about this and how it's treated, see our articles on Erection problems.
• They cannot release sperm (ejaculate) from their penis .
• There is a blockage in the tubes between their testicles and their penis. This can happen for several reasons, such as a sterilization operation (vasectomy) or an infection.
• Semen is going backward into the bladder instead of toward the penis. This is called retrograde ejaculation. It happens if the valves at the opening of the bladder do not close properly when a man is having sex. It can be caused by damage to the nerves. Nerve damage may be caused by diabetes or by surgery in this area.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.