Sarah Murnaghan was successfully moved to the adult donor list after a federal judge ordered Health and Human Services Secretary Kathleen Sebelius to circumvent existing rules that require potential recipients to be at least 12 years old.
A review board decided Monday to revise the policy so child candidates could appeal.
Her family confirmed on Facebook Wednesday morning that a donor had been found, and Sarah would head into surgery immediately.
"She will be taken back to the OR in 30min," Sarah's mother, Janet Murnaghan wrote. "Please pray for Sarah's donor, her HERO, who has given her the gift of life."
Sen. Pat Toomey, R-Pa., who had become involved in Sarah's case, released a statement Wednesday morning.
"I am deeply grateful to the organ donor and his or her family for the potentially life-saving gift to Sarah," Toomey said. "Now that a suitable donor has been found, a prayer would help, too -- a prayer Sarah's body accepts the new organ the way doctors believe it can. The judge gave Sarah a chance to receive a new lung. Now the surgical team at CHOP is giving her a chance at life."
Sarah's surgery is expected to take hours.