However, a vasectomy does NOT protect against sexually transmitted infections such as chlamydia, syphilis, hepatitis B or HIV.

Having a vasectomy does not alter the sex drive, or the enjoyment of sex, since testosterone continues to be produced as normal. The only difference is that men after a vasectomy produce semen that contains no sperm. The testis continue to produce sperm as usual but these are reabsorbed by the body harmlessly.

The decision to undergo a vasectomy should be a careful one and one taken by the couple together. However, legally in the UK, a man does NOT have to consult his partner before he can have a vasectomy operation.

Vasectomies are usually requested by those couples who are absolutely certain that they have completed their families and will not wish to extend their families further. It is therefore usual for a man to be at least in his 30's.

Although a general anaesthetic can be used, typically, vasectomies are done as day case procedures under local anaesthesia only. They can be performed in some GP surgeries, hospital clinics or private clinics. There is no pain through the procedure but some pulling can sometimes be felt.

A vasectomy operation involves numbing the skin on each side of the scrotum with local anaesthetic and making a tiny incision. From this cut, the vas deferens (tube through which the sperm pass during ejaculation) is pulled out. A portion from the middle of each tube is removed, the ends tied separately so that they do not meet and the incisions finally stitched or taped. In come centres, a "no-scalpel" technique is used where tiny punctures are made instead of incisions. These heal quicker and require no stitching.

However, conception after a vascetomy operation can stil take place for several weeks. This is because sperm will already be present in the vas deferens before the operation and will appear in the semen on ejaculation. Men are therefore asked to produce 2 semen samples 8 weeks and 12 weeks after a vasectomy to confirm sterility of the semen. It is only at this stage when the laboratory result confirms the absence of sperm that the operation can be deemed successful and full contraception assumed.