What is a sentinel pile?

Sentinel pile refers to a frequently recurring anal fissure caused by a previous hemorrhoid. The initial hemorrhoid is a manifestation of chronic anal rupture, which clinically presents with recurrent episodes over a long duration, prolonged pain after defecation lasting for several hours at times. Due to the non-healing anal fissure, the skin below the裂 (fissure) is chronically inflamed, leading to inflammation-induced stimulation, impaired venous and lymphatic return, resulting in tissue edema and fibrotic changes that form an external connective tissue mass.