A team of six surgeons in the U.S., after 25 hours of complex surgery have successfully separated four-year-old conjoined twin sisters.

The girls Kendra and Maliyah Herrin, were born fused together mid-torso and shared one kidney, one set of legs, of which each controlled one, and part of the large intestine.

The surgery will hopefully allow them to lead independent lives.

The team at Primary Children’s Hospital, Salt Lake city comprised two anesthesiologists, one radiologist, two urologists and 25 to 30 support staff members.

Doctors at the hospital believe this was the first known surgical attempt to separate twins with a shared kidney.

The operation which lasted 24 hours has left each girl with one leg, while their liver and intestines have been split and their bladders and pelvises reconstructed.

Kendra has kept their previously shared kidney and Maliyah is on dialysis until she is strong enough to receive a kidney transplant from her mother, which could take up to six months.

Preparations for the surgery have been underway since June 23, when doctors implanted 17 expanding balloons into their torso which when filled with a saline solution have been expanding the skin and muscles that plastic surgeons will use in closing their abdomens after surgery.

The girls who are blue-eyed with sandy-hair, were born locked together in an embrace, almost face to face; their parents say the twins were very brave.

Conjoined twins are a rare occurrence and only happen about once in every 50,000 to 100,000 births; as a rule only around 20 percent survive to become viable candidates for separation.

Surgery is usually conducted between 6 to 12 months of age but in this case, as the twins shared a kidney and Maliyah had difficulty gaining weight, along with Erin Herrin’s pregnancy last year with a set of twin boys, who are not conjoined, making her ineligible to donate her kidney, the surgery was delayed.

Medical ethicists who had questioned separating the twins because of the significant risks of kidney dialysis and transplant for Maliyah, have met with doctors and the girls’ parents.

But the parents Jake and Erin Herrin, who have 6-year-old daughter, as well as 14 month twin boys, decided in February to proceed as they say the girls see themselves as living separate adult lives.

While the separation surgery has been successful, doctors stress the the two little girls have a long way to go yet.

Dr. Rebecka Meyers, the hospital’s chief of pediatric surgery says there are big concerns with both girls, with Maliyah it is her kidney function and her dialysis and with Kendra it is the coverage of her abdomen.