Positive Oral Contrast Solution at MDCT for Suspected Acute Appendicitis in Adults: Rate of Appendiceal Luminal Filling of Normal and Inflamed Appendixes.

Abstract

OBJECTIVE. The purpose of this study was to assess the rate of appendiceal filling with a positive oral contrast solution at MDCT performed for suspected acute appendicitis in adults. MATERIALS AND METHODS. We performed a retrospective review of MDCT in 684 consecutive adult patients with suspected acute appendicitis in a 19-month period. Patients were excluded if no positive oral contrast solution (500 mL each of water and polyethylene glycol and 30 mL diatrizoate) was given or if the appendix was not visible or absent. After exclusion, images of 519 patients (mean age ± SD, 37.4 ± 16.0 years; 335 women, 184 men) were reviewed for cecal contrast opacification and appendiceal filling. Imaging findings were recorded as positive or negative for acute appendicitis using all available clinical and pathologic data as a reference standard. A control series of CT colonography (CTC) screening examinations (overnight preparation with universal cecal opacification) in 2552 adults without symptoms of appendicitis was also reviewed. RESULTS. Cecal opacification was confirmed in 313/519 (60.3%) patients, with no difference between those considered to be positive (68/107, 63.6%) or negative (245/412, 59.5%) for appendicitis (p = 0.506). When positive oral contrast solution reached the cecum, appendiceal filling was seen in none of the 68 (0%) with appendicitis and in 205 of the 245 (83.7%) without appendicitis (p < 0.0001). Among CTC control subjects, appendiceal filling was similar to the cohort considered to be without appendicitis (2240/2552 [87.8%], p = 0.070). CONCLUSION. In MDCT for suspected acute appendicitis, luminal filling of the noninflamed appendix exceeds 80% when positive oral contrast solution reaches the cecum, indicating results similar to screening CTC. The appendix did not fill in proven acute appendicitis, indicating appendiceal filling may allow exclusion of appendicitis with high certainty. These results suggest positive oral contrast solution may augment diagnostic accuracy and confidence in cases of suspected acute appendicitis.