Objectives: The definitive diagnosis of acute appendicitis can be difficult, and computed tomography (CT) scanning is playing a larger role in assessment of the clinical picture in patients with presumed appendicitis. Therefore, utilization of CT scans in patients with presumed appendicitis was evaluated at a single institution in order to determine the sensitivity, specificity, and effect on clinical outcome.
Methods: Adult patients (age >18 yrs) with appendicitis were identified from hospital records. Findings at surgery, including the incidence of perforation, were correlated with imaging results.
Results: During a 3-year period, 410 patients underwent appendectomy for presumed acute appendicitis at our institution. Of these patients, 255 (62%) underwent pre-operative CT and the remaining 155 (38%) patients did not have imaging prior to surgery. Patients who underwent CT were older and more likely to be female (Table). The mean white blood cell (WBC) counts at presentation to the emergency room (ER) were similar between the two groups. Importantly, when examining the time interval between arrival in the ER to the operating room, patients who had a pre-operative CT had a longer time period compared to those who did not. Moreover, this possible delay in intervention was associated with a higher rate of appendiceal perforation in the CT group. CT had an overall 93% sensitivity and a 59% specificity for acute appendicitis.
Conclusions: Pre-operative CT scanning in patients with presumed appendicitis should be used very selectively as widespread utilization may adversely affect outcomes. The potential negative impact of CT imaging includes a delay in operative intervention and a potentially higher perforation rate.

	Age(years)	%Female	WBC count	Time from ER to OR (hours)	% Laparoscopic	OR time (hours)	% Perforation
CT	37±1	50%	13.6±0.3	8.2±0.3	87%	1.2±0.1	17
No CT	31±1	34%	14.4±0.3	5.1±0.2	95%	1.2±0.1	8%
P-VALUE	<0.001	0.001	NS	<0.001	0.021	NS	0.015

mean±SEM, NS=not significant