Jodie and Mary: The operation

The operation to separate Siamese twins Jodie and Mary is set to go ahead after a decision by their parents not to continue their legal battle to keep the girls together.

The operation is expected to be carried out within a matter of weeks.

According to experts, the surgery may be performed when the twins are three months old in early November.

However, doctors at St Mary's Hospital in Manchester, where the twins were born, are keeping both girls under close supervision and have pledged to bring the surgery forward if their condition deteriorates.

The hospital has said the surgery will not go ahead with the explicit knowledge of the parents, even though they have been strongly against separating the girls.

Abdomen

The twins are joined at the abdomen, have a fused spine and share the same blood supply.

Jodie has a normal brain, heart, lung and liver. She appears to have a separate bowel, although the twins share a bladder.

She has two normal legs and a dislocated pelvic joint which has made the limbs lie at right angles to the spine.

Mary feeds on Jodie's vital organs to survive. Her heart and lungs are so poorly developed that she is totally dependent on her sister for oxygen and blood circulation.

Doctors believe that Jodie could survive separation because her long-term problems are "functional" rather than life threatening.

The only threat posed to Jodie, say doctors is that Mary is sapping her strength.

Separation would lead to the immediate death of Mary.

The operation to separate will begin with surgeons cutting off the blood supply to Mary. They will then separate the twins carefully working around Jodie's vital organs.

The doctors are then expected to work to ensure that Jodie is able to empty her bladder and bowel effectively. This may be achieved with a colostomy.

She will need orthopaedic surgery to relocate the joint at the back of the pelvis.

Doctors will also consider whether to take skin from Mary to "cover up" Jodie's wounds from the surgery.

The operation will be carried out by a team of doctors, all specialist paediatricians and is expected to last the best part of a full day.

Surprises

One of the problems with separating Siamese twins is that often "surprises" occur during the surgery.

Despite many tests, medical technology is not able to predict everything that the doctors will see or encounter when they begin the operation.

However, experts are confident that the operation will enable Jodie to live a normal life.

It was for that reason they brought their case to the courts to have the twins separated.

It is unclear whether the separation will be performed at St Mary's Hospital in Manchester or at Great Ormond Street Children's Hospital in London, where doctors have carried out a number of similar operations.