Having a sterilisation operation is a permanent form of contraception, used by people who are certain they don't want to have (any more) children.
Female sterilisation requires minor surgery by a gynaecologist. Sometimes this is called "getting your tubes tied".
The fallopian tubes which carry the egg from the ovary to the womb are sealed off. Various techniques are used but the most common one in New Zealand at present is the application of a clip to block the fallopian tubes. This can be done through a small incision using an instrument called a laparoscope.
Failures following sterilisation are rare, about zero to five per 1,000 cases.
Also known as "the snip". This is male sterilisation where the tube (vas deferens) which carries the sperm from the testis is cut and sealed off.
The operation is done in a clinic or surgery under a local anaesthetic. It is a simpler operation than female sterilisation, and doesn't affect his hormones or sex drive.
The man is not sterile immediately because there are still sperm in the storage areas and on average it will take 16 ejaculations or three months for these stored sperm to be cleared out of the system.
Failures are most likely to occur before the system is clear of sperm but even after this there is a rare chance that the tubes can rejoin, about one in a thousand.