Fissure in ano:
A fissure is a small cut at anus which occurs when hard stool is forced out by straining. It gives severe pain while passing stool and small amount of bleeding. It is caused by constipation and in patients having a non vegetarian, spicy, low fiber diet. It can be treated by medications or in some severe cases, with surgery.
Piles are normal veins present in the anus which gradually increase in size and give symptoms of pain and bleeding. They are also more common in patients with chronic constipation and low fiber diet. In early stages, they can be treated with medications but later stages require surgery. Surgery can be done by open or stapled technique.
Infection in the anal canal can give rise to pus and abscess formation which needs emergency surgery to remove the pus.
Fistula in ano:
Infection in the anal region can give rise to fistula which causes pus discharge from another opening near the anus. This requires surgical treatment to remove the abnormal fistulous tract.
Infection caused by hair in the gluteal cleft results in pilonidal sinus formation. It needs surgical complete removal of the sinus.