The Role of Computed Tomography in the Diagnosis of Acute Appendicitis David L. Stroman, MD, Charles V. Bayouth, MD, Joseph A. Kuhn, MD, Matthew Westmoreland, MD, Ronald C. Jones, MD, Tammy L. Fisher, RN, Todd M. McCarty, MD, Dallas, Texas BACKGROUND: Routine contrast-enhanced com- puted tomography (CECT) has been described as an accurate diagnostic imaging modality in pa- tients with acute appendicitis. However, most patients with acute appendicitis can be diag- nosed by clinical findings and physical exam alone. The role of CECT in patients suspected of having appendicitis but with equivocal clinical exams remains ill defined. METHODS: One hundred and seven consecutive patients who were thought to have appendicitis but with equivocal clinical findings and/or physi- cal exams were imaged by CECT over a 12- month period. Oral and intravenous contrast-en- hanced, spiral abdominal and pelvic images were obtained using 7-mm cuts. CECT images were interpreted by a board-certified radiologist. Main outcome measures included CECT sensitivity, specificity, positive predictive value (PPV), nega- tive predictive value (NPV), and accuracy in the diagnosis of acute appendicitis, comparing CECT with ultrasound, and determining the im- pact of CECT on the clinical management of this patient population. RESULTS: A group of 107 patients consisting of 44 males (41%) and 63 females (59%) with a median age of 33 years (range 13 to 89 years) were im- aged with CECT to evaluate suspected appendi- citis. Of the 107 CECTs performed, 11 false-posi- tive and 3 false-negative readings were identified, resulting in a sensitivity of 92%, speci- ficity of 85%, PPV of 75%, NPV of 95%, and an overall accuracy of 90%. Forty-three patients were imaged with ultrasound and CECT, and CECT had significantly better sensitivity and ac- curacy (30% versus 92% and 69% versus 88%, P <0.01). With regard to clinical management, 100% (36/36) of patients with appendicitis, and 4.2% (3/71) of patients without appendicitis un- derwent appendectomy. Therefore, the overall negative appendectomy rate was 7.6% (3/39). CONCLUSIONS: CECT is a useful diagnostic imag- ing modality for patients suspected of having acute appendicitis but with equivocal clinical findings and/or physical exams. CECT is more sensitive and accurate than ultrasound and is particularly useful in excluding the diagnosis of appendicitis in those without disease. Am J Surg. 1999;178:485– 489. © 1999 by Excerpta Medica, Inc. A ppendicitis represents one of the most common surgical disorders encountered, reported to affect more than 250,000 people annually. Typically, the diagnosis can be made from well-established clinical crite- ria, with an accepted negative appendectomy rate from 7% to 25%. 1,2 However, other conditions may mimic the clin- ical prodrome of appendicitis, and differentiating among these has been the focus of much debate. When surgical intervention is performed in this group of patients, the negative appendectomy rate approaches 50%. 3 Although abdominal ultrasound has been advocated as a diagnostic imaging modality in this subgroup of patients, it is primar- ily limited to identifying ovarian pathology. With the growing availability and resolution of contrast-enhanced computed tomography (CECT), CECT has been reported as both accurate and useful for patients with appendici- tis. 4,5 Unfortunately, experience with CECT in the past has included all patients with suspected appendicitis. 6–8 The value of CECT in patients thought to have appendi- citis but with equivocal clinical findings remains ill de- fined. This study was designed to determine the sensitivity, specificity, accuracy, and impact of CECT on patients with equivocal clinical data suspicious for appendicitis. These results would then be compared with abdominal ultrasound and the clinical impact of CECT in this challenging group of patients determined. MATERIALS AND METHODS Over a 12-month period (December 1, 1997 to December 1, 1998), 107 patients with suspected appendicitis but with equivocal symptoms underwent dual-phase CECT. Initial clinical evaluation was made by a board-certified surgeon (72%), board-certified emergency medicine physician (40%), surgical resident (83%) or a combination of these in each case. All patients were felt to have equivocal clinical signs for appendicitis and underwent CECT as part of the initial clinical evaluation. The results of the CECT were then used to assist with management decisions. Patients were imaged using a GE 9800 CT scanning machine (General Electric Co., Milwaukee, WI) located in the emergency room. Each patient was given 20 cc of barium contrast diluted in approximately 500 mL of water over a 2-h period before imaging. Patents also received a From the Department of Surgery, Baylor University Medical Center, Dallas, Texas. Requests for reprints should be addressed to Todd M. McCarty, MD, 3409 Worth St., #420, Dallas, Texas 75246. Presented at the 51st Annual Meeting of the Southwestern Surgical Congress, Coronado, California, April 18 –21, 1999. © 1999 by Excerpta Medica, Inc. 0002-9610/99/$–see front matter 485 All rights reserved. PII S0002-9610(99)00223-8