Plain film of the abdomen from a patient with toxic megacolon associated with Clostridioides (formerly Clostridium) difficile infection. The large and small intestines are grossly dilated. Dilatation of the small bowel, which has the thin transverse folds of the valvulae conniventes (arrowhead), is seen best in the left lower quadrant. Large bowel dilatation occupies most of the right lower quadrant and has characteristic thick haustral markings that do not extend across the entire lumen (arrows).
