What is the medical term meaning abnormal passage between two organs or leading from an organ to the surface of the body?

anastomosis
This is a fistula. The plural of fistula is both fistulas and fistulae.
An abnormal passage between two internal organs is known as a fistula. Medically, a fistula is defined as any abnormal communication between two organs, vessels, or body cavities that are lined by epithelium.