The difference between stage I, II and III anal fissures: stage I anal fissures are simple anal fissures, the first occurrence of anal fissures, superficial longitudinal fissures of the skin of the anal canal, the wound edge is neat and tender, there is tenderness, the wound surface is elastic, the joint longitudinal muscle fibers are visible on the wound surface. Stage II anal fissure is a period of ulcer formation, with irregular thickening and elevation of the trabecular margin, poor elasticity of the hard nodules, non-fresh trabeculae with obvious ulcers, dark red ulcer base or purulent secretions, and congestion of the surrounding mucosa. Stage III anal fissures are hardened ulcer margins with purulent discharge at the base, often combined with anal papillomegaly, anterior hemorrhoids and subcutaneous fistulae.