(1) Stage I anal fissure: superficial longitudinal fissures of the anal canal skin with neat margins, fresh base, red color, obvious tenderness, and elasticity of the wound surface. (2) Stage II anal fissure: history of recurrent anal fissures. The margin is irregular, thickened, poorly elastic, and the base of the ulcer is purplish red or with purulent discharge. (3) Stage III anal fissure: hardened ulcer margins, purple-red base, and purulent discharge. There is hypertrophy of the anal papilla at the upper end adjacent to the anal sinus, sentinel hemorrhoids at the lower end of the trauma margin, or subcutaneous fistula formation.