Clinically, the diagnosis of shigellosis can be established only in cases of a typical colitis variant of the course of the disease. To clarify the diagnosis in unconfirmed laboratory cases, a sigmoidoscopy is performed, which in all cases of shigellosis reveals a picture of colitis (catarrhal, hemorrhagic or erosive-ulcerative) with lesions of the mucous membrane of the distal colon, often sphincteritis.