Computed tomography scanning for the diagnosis of perforated appendicitis

The optimal initial treatment for perforated appendicitis may be nonoperati ve. For this reason it is important to be able to reliably distinguish betw een acute and perforated appendicitis. CT scanning has been shown to be hig hly accurate for the diagnosis of appendicitis, but it has not been specifi cally evaluated for perforated appendicitis. Our objective was to evaluate CT for the diagnosis of perforated appendicitis. Our study population compr ised 84 patients who underwent appendectomy between 1993 and 1997 and who h ad CT scanning performed preoperatively. Medical records were reviewed retr ospectively. CT scans were reviewed in a blinded fashion. CT findings were correlated with pathologic and clinical factors. Sixteen patients with acut e appendicitis, 59 patients with gangrenous or perforated appendicitis, and 9 patients with normal appendices or other diagnoses were evaluated. For p atients with pathologic documentation of appendicitis, CT findings that ind ependently predict perforation or gangrene included abscess (P < 0.001), ph legmon (P < 0.001), extraluminal gas (P = 0.01), and terminal ileal wall th ickening (P = 0.03). CT findings of an abscess, extraluminal gas, or phlegm on have a sensitivity of 92 per cent, specificity of 88 per cent, positive predictive value of 96 per cent, and negative predictive value of 74 per ce nt for perforated or gangrenous appendicitis. We conclude that CT can relia bly distinguish between acute and perforated appendicitis.