Sterilisation is difficult and expensive to reverse so think twice before choosing this option, says Dr Gillian Lockwood

The decision to be sterilised is often, unfortunately, taken in haste and repented at leisure. Women may be unhappy with their method of contraception or have had a particularly difficult, disastrous or unplanned pregnancy.

Men may be certain that they will never want to father another child, or be anxious about failure rates with the Pill or condoms. But sterilisation must be regarded as an irrevocable decision and, in today's world where nearly 40 per cent of marriages end in divorce, couples must be aware that they may want to have more babies someday, somewhere else - and with someone else.

If you have been sterilised and now regret that decision, what are the options?

Female sterilisation
The vast majority of female sterilisation operations involve placing little clips or loops around the Fallopian tubes, which block the tube and prevent egg and sperm from meeting.

This procedure is done by laparoscopy - an operation that involves placing a fine telescope with a light on the end through a tiny cut in the abdomen (in the belly button). This allows the surgeon to inspect the pelvis - particularly the uterus, ovaries and Fallopian tubes. A laparoscopy is done as a day case in hospital and is performed under a general anaesthetic.

It is possible to reverse this operation by cutting out the damaged section of tube and joining the ends back together. However, this is a very complex operation, usually involving microsurgery (the Fallopian tubes are less than one millimetre in diameter).

Success rates vary from 20-80 per cent, depending on the skill of the surgeon, the age of the woman and the time since the sterilisation was performed.

If the original operation was a tubal ligation - in which the tubes were cut and 'tied off' or 'heat-sealed' with diathermy, success rates for reversal are lower. All women who get pregnant after reversal of sterilisation are at an increased risk of an ectopic pregnancy.

Getting around the problem
The alternative for women wanting to get pregnant after sterilisation is IVF, the 'test-tube baby' technique. In IVF, egg and sperm are mixed in little glass dishes so that fertilisation takes place. The resulting embryos are placed directly in the uterus, thereby by-passing the blocked tubes.

IVF is a better option than attempted reversal of sterilisation if the woman is older than 35 years, if she has any other fertility problems (such as endometriosis or polycystic ovaries) or if her partner has poor sperm.

Reversal of sterilisation is not usually available on the NHS and the operation costs about £2,500-£3,500. IVF costs about £1,500-£2,000, and again is rarely available to women on the NHS if they already have children and have been sterilised.

Some fertility clinics offer 'egg-share' IVF which is a way in which women may have free or subsidised IVF in return for giving up half their eggs to a couple who need donated eggs.

Male sterilisation
There is a reasonable chance of a reversal of vasectomy producing a good result as long as the original operation was performed less than 10 years beforehand and there were no complications (infection or scarring) at the time.

However, reversals are rarely available on the NHS and usually cost £1,500-2,000 when done privately. Success rates are 50-80 per cent, but the sperm quality is often not as good as before the original vasectomy because of anti-sperm antibodies.

Anti-sperm antibodies are formed when a man's immune system comes into contact with his sperm. Normally the immune cells (the white cells in the blood) are kept away from the sperm by the 'blood-testis' barrier. But if the man has surgery in the scrotal area (vasectomy, reversal or trauma/infection) the barrier is breached and anti-sperm antibodies can form. These have the effect of coating the sperm tails and sticking them together so the 'swimming ability' of the sperm is severely reduced.

Even when the operation is initially successful, the delicate tubes (the vas deferens) may block off again quite soon, and the man should have sperm cryopreserved (frozen) just in case.

If the vasectomy reversal fails, sperm can be obtained directly from the testes by a minor outpatient operation called PESA (percutaneous epididymal sperm aspiration) or TESE (testicular sperm extraction).

Since the quantities of sperm obtained at PESA or TESE are very small, and the sperm is immature, it is necessary to use the ICSI technique to ensure that the woman's eggs are fertilised. This involves the woman undergoing an IVF cycle and her eggs being retrieved as in the 'test-tube baby' technique.

PESA/TESE costs £800-1,000 and ICSI costs an additional £2,500-3,500, so it is an expensive option. However, it is a very successful treatment and does offer the couple the chance of having their own genetic baby.

The other option, the use of donor sperm, is much cheaper (£200-350 per cycle), but many men have reservations about 'raising another man's child.'