In adults with suspected appendicitis, which imaging modality is commonly first-line and what findings support the diagnosis?

In adults with suspected appendicitis, which imaging modality is commonly first-line and what findings support the diagnosis?

• A. CT abdomen with IV contrast; findings include appendiceal diameter >6 mm, wall thickening, periappendiceal fat stranding.
• B. Ultrasound is first-line; findings include appendiceal wall calcification.
• C. MRI without contrast; findings include gas in appendix.
• D. Plain X-ray is first-line; gas in appendix.

Answer: (A)

In adults with suspected appendicitis, CT of the abdomen with IV contrast is preferred because it quickly provides a reliable diagnosis and can reveal complications or alternative causes. The key CT findings that support appendicitis are a dilated appendiceal lumen (typically diameter greater than about 6 mm), wall thickening with enhancement after contrast, and inflammation around the appendix shown as periappendiceal fat stranding. This combination is highly specific for appendicitis and helps differentiate it from other causes of acute abdominal pain. Ultrasound, while useful in children or pregnant patients, is more operator-dependent and can be less reliable in adults due to body habitus and appendix location; it would show a noncompressible, blind-ending tubular structure in the right lower quadrant with wall thickening, but it lacks the overall diagnostic accuracy of CT in adults. MRI without contrast is another alternative when CT is not suitable, such as in pregnancy, with similar signs of an enlarged, thick-walled appendix and periappendiceal edema, but it is not the typical first-line study. Plain X-ray is not used for initial evaluation due to its poor sensitivity for appendicitis.

In adults with suspected appendicitis, CT of the abdomen with IV contrast is preferred because it quickly provides a reliable diagnosis and can reveal complications or alternative causes. The key CT findings that support appendicitis are a dilated appendiceal lumen (typically diameter greater than about 6 mm), wall thickening with enhancement after contrast, and inflammation around the appendix shown as periappendiceal fat stranding. This combination is highly specific for appendicitis and helps differentiate it from other causes of acute abdominal pain.

Ultrasound, while useful in children or pregnant patients, is more operator-dependent and can be less reliable in adults due to body habitus and appendix location; it would show a noncompressible, blind-ending tubular structure in the right lower quadrant with wall thickening, but it lacks the overall diagnostic accuracy of CT in adults. MRI without contrast is another alternative when CT is not suitable, such as in pregnancy, with similar signs of an enlarged, thick-walled appendix and periappendiceal edema, but it is not the typical first-line study. Plain X-ray is not used for initial evaluation due to its poor sensitivity for appendicitis.