Koop was appointed surgeon-in-chief at Children’s Hospital in Philadelphia and he also served as a professor at the University of Pennsylvania School of Medicine.
He pioneered surgery on newborns and successfully separated three sets of conjoined twins. He won national acclaim by reconstructing the chest of a baby born with the heart outside the body.
Although raised as a Baptist, he was drawn to a Presbyterian church near the hospital, where he developed an abiding faith. He began praying at the bedside of his young patients — ignoring the snickers of some of his colleagues.
“It used to be said in World War II that there were no atheists in foxholes,” he wrote in 1973. “I have found there are very few atheists among the parents of dying children.
“This is a time when religious faith can see a family through trying circumstances.”
• Ring reported from Montpelier, Vt. Cass reported from Washington.