PHILADELPHIA, Pa. (AP) - Officials at Children's Hospital of Philadelphia say they've successfully separated 10-month-old conjoined twins during an 11-hour surgery.

The hospital said Tuesday sisters Erin and Abby Delaney, of North Carolina, are recovering in the intensive care unit after last week's procedure. The hospital says the surgery was carefully orchestrated, down to marking monitors and equipment with green or purple tape, one color assigned to each girl.

It's the 23rd time the hospital has separated conjoined twins.

The girls were joined at the top of their heads, described as the least common type of conjoined twins. They were born 10 weeks prematurely in late July by cesarean section.

The hospital declined to disclose the family's hometown.