Integrated Problems Radiology: Abdominal Pain

These are two additional images from the patient's study, at lower positions in the abdomen. You should be able to pick out the bowel loops with thick walls and the adjacent stranding that makes the margins of the involved bowel more 'fuzzy' than other structures in the patient's abdomen. Since we are in the right lower quadrant of the abdomen, what other important structure should we be looking for that is NOT clearly seen on any of these images?