In adults with suspected appendicitis, which imaging modality offers the highest sensitivity and specificity?

• A. CT abdomen/pelvis with IV contrast
• B. Right upper quadrant ultrasound
• C. Abdominal X-ray
• D. MRI abdomen

Answer: (A)

In adults with suspected appendicitis, contrast-enhanced CT of the abdomen and pelvis provides the highest sensitivity and specificity. CT visualizes the appendix in detail, showing wall thickening, enhancement, and periappendiceal fat stranding, and it can detect an appendicolith and other findings that distinguish appendicitis from alternative causes of right lower quadrant pain. It also reliably identifies complications like perforation or abscess and helps rule out other intra-abdominal processes, which is why its diagnostic accuracy is superior to other imaging options.

Ultrasound can be helpful and is preferred in children and pregnant patients because it avoids radiation, but in adults its accuracy is more variable and often operator-dependent, especially in those with larger habitus or gas. Right upper quadrant ultrasound is aimed at biliary disease rather than appendicitis and isn’t ideal for diagnosing appendicitis. Abdominal X-ray has very limited utility for this condition and misses many cases. MRI offers excellent accuracy and has the advantage of no radiation, but it is less practical in the acute setting due to availability, time, and cost; it’s used when CT is contraindicated or in specific populations.