A 22-member surgical team at the Johns Hopkins Children's Center successfully performed a rare operation separating five-day-old Siamese twin sisters, hospital officials said yesterday.

The operation was one of about two dozen ever successfully completed, hospital officials said.

The twins, Emily and Francesca Selvaggio, were born Tuesday in Salisbury, Md. They were in serious but stable condition following the 10-hour operation. Joined from the chest to the upper abdominal muscle and rib cartilage, the twins also shared a liver and an umbilical cord and suffered from an intestinal obstruction, according to a hospital statement released last night.

Dr. J. Alex Haller Jr., who headed the team, said the physicians were determined to save both babies' lives. The operation was essentially one of dividing the twins and reconstructing the hole left in their chests and stomachs.

The babies were delivered Tuesday at a Salisbury hospital, weighing a total of 15 lbs. and were brought to Hopkins, about 150 miles away, by ambulance. Their parents are Charles and Carol Selvaggio of Dagsboro, Del.

Extensive tests, including CAT scans and ultrasound, were conducted at the hospital's Neonatal Intensive Care Unit.

"Our first and most important finding was that the girls had two separate hearts," Haller said. He did not know until the operation that the hearts were in two separate normal sacs, according to hospital officials.

The fused liver was the most serious problem, because of potential blood loss and shock from cutting the organ.

The surgical team worked on the twins for 10 hours and took special logistical precautions. They separated into two teams--one group wearing white, the other blue surgical gowns--so there would be no confusion about which baby they were monitoring.

After the twins were separated, a second team of surgeons headed by Dr. David L. Didgein, closed the raw edges of the liver, repaired and reconstructed the intestines and closed the large abdominal wound. Because the twins did not have sufficient abdominal wall, surgeons used plastic mesh to fill the gap.