Acute appendicitis is one of the most common causes of sudden, severe abdominal pain. It usually requires emergency removal of the appendix, a surgical procedure called an appendectomy. Diagnosis can be difficult because no single sign, symptom, or test can accurately confirm the diagnosis in all cases before surgery. Doctors often use computed tomography (CT or “CAT”) scans, which allow them to view the inside of the abdomen and pelvis in a quick, noninvasive manner. Newer, multidetector CT provides clearer images than older CT technology.