Left lower-quadrant pain: guidelines from the American College of Radiology appropriateness criteria.

The differential diagnosis of left lower-quadrant pain includes gastrointestinal, gynecologic, and renal/ureteric pathology. Imaging is helpful in evaluating left lower-quadrant pain, and is generally guided by the clinical presentation. Acute sigmoid diverticulitis should be suspected when the clinical triad of left lower-quadrant pain, fever, and leukocytosis is present. The severity of disease varies from mild pericolonic and peridiverticular inflammation to severe inflammatory changes with complications such as perforation, peritonitis, or abscess or fistula formation. Computed tomography is the preferred test in evaluating clinically suspected diverticulitis. It is used to evaluate the severity and extent of disease and to identify complications, but it also may diagnose other causes of left lower-quadrant pain that can mimic diverticulitis. Magnetic resonance imaging can be used to assess left lower-quadrant pain. It has superior resolution of soft tissues and does not expose the patient to ionizing radiation, but it is expensive and requires more time to perform. Transabdominal ultrasonography with graded compression is another effective technique but is limited by its high operator dependency and technical difficulties in scanning patients who are obese. Pelvic ultrasonography is the preferred imaging modality in women of childbearing age. Radiography with contrast enema is less sensitive than computed tomography in diagnosing diverticulitis and is seldom used.