Anal fissure and fistula are two highly critical conditions that demand prompt medical attention and treatment from the best hospital for fissure surgery. An anal fistula is a condition in which a microscopic tunnel develops between the anus and the skin surrounding it.Overview Anal fissure and fistula are two highly critical conditions that demand prompt medical attention and treatment from the best hospital for fissure surgery. Irene Hospital is one of the Best Hospital for Fistula Surgery in Delhi.