The typical case of acute sigmoid diverticulitis appears with fever, leukocytosis, and pain and tenderness in the left lower quadrant. The patient may or may not have a palpable mass in the lower abdomen or in the pelvis. The best imaging technique for diagnosing a diverticulitis phlegmon is computed tomography. Initial therapy depends upon intravenous antibiotics and nasogastric suction. After 2–3 days the patient is much improved. Tenderness and fever will diminish. By the end of a week the pelvic or abdominal mass may no longer be palpable. After three weeks a barium colon enema radiographic study may be performed. If this is the patient’s first attack, surgery is not generally indicated unless the X ray shows an extravasation of contrast material outside the lumen of the colon.