It was the first successful operation of its kind in North China and the fourth successful separation in China.

The female twins were connected at the chest, stomach and heart. They shared one liver and one pericardium, a membranous sac enclosing the heart.

It was an extremely rare and complicated case, making the surgery even more risky.

Doctors from the hospital's skin, heart, pediatric, anesthesia and plastic surgery departments put together an operation plan on Tuesday after a series of discussions.

The operation started at 10 am yesterday and the girls' hearts were separated about four hours later. Their livers were separated three hours after that, towards the end of the procedure. The babies were born to a farming family in Zhangjiakou on June 20.

The No 251 Hospital of the People's Liberation Army decided to perform the operation and give the girls continued treatment as their parents were not able to afford the procedure.

Two nurses have been taking care of the twins since they arrived at the hospital. They washed the girls each day and rubbed their connected skin from time to time to lengthen it for the operation.

There is only one set of Siamese twins in every 50,000 to 100,000 pregnancies. But only one in 200,000 newborns are Siamese twins as most of them die before being delivered.

According to experts, Siamese twins are formed when the ovum does not completely separate into two individual cells.

China's other three successful separations occurred at Xinqiao Hospital of No 3 Military University in Southwest China's Chongqing Municipality, the No 1 Hospital of the Fujian Medical University in East China's Fujian Province and a hospital in Harbin in Northeast China's Heilongjiang Province.

(China Daily August 22, 2002)