Children presenting with atypical symptoms of appendicitis require imaging to make a diagnosis. Ultrasonography has been successfully used for this purpose for many years, but accuracy is operator-dependent and decreases with retrocecal location of the appendix. Computed tomographic (CT) scanning localized to the right lower quadrant with rectal contrast material has been used to identify appendicitis in adults and children. Oral and intravenous contrast, however, are still more commonly used than rectal contrast. Fefferman and associates studied the accuracy of limited CT scanning with oral and intravenous contrast in diagnosing appendicitis in children at a single institution.
The authors performed a retrospective review of abdominal CT scans with oral and intravenous contrast performed on children presenting to the emergency department with atypical manifestations of appendicitis. The median age of the 93 children included in the study was 13 years. The scans were interpreted after division into three regions: (1) the area above the lower pole of the right kidney, (2) the area between the lower pole of the right kidney and the iliac crest, and (3) the area below the iliac crest. The relative importance of the findings in each region were recorded and compared. The criteria used to diagnose appendicitis were a peripherally enhancing fluid-filled tubular structure in the absence of a normal appendix, inflammation with an appendicolith, and the presence of right lower quadrant inflammation without clear identification of the appendix. The results of surgical pathology and CT findings were correlated.
Thirty-eight cases of appendicitis were diagnosed among the 55 abnormal CT scans. Adnexal cysts and mesenteric adenitis were the next most common abnormal findings. Appendicitis was found in all 35 children who underwent surgery. Thirty-four children had positive CT evidence of appendicitis. Of the remaining positive CT scans, four were false-positive. In addition, one CT scan was false-negative. This examination method demonstrates a sensitivity of 97 percent, a specificity of 93 percent, a positive predictive value of 90 percent, and a negative predictive value of 98 percent.
There was significantly higher statistical accuracy among the helical scans. The most common diagnostic criteria for appendicitis was located in the region below the iliac crest, and a minority occurred between the iliac crest and the lower pole of the right kidney.
The authors report that, in their analysis, CT imaging with contrast focused on the region below the lower pole of the right kidney effectively identified appendicitis in the large majority of children and also detected most other potential disorders. Helical technique was more sensitive than nonhelical CT imaging. They conclude that focused CT with contrast materials is appropriate in the evaluation of children with symptoms of appendicitis. Because exposure to ionizing radiation should be kept to a minimum, the authors suggest it may be prudent to look more closely at ultrasonography for first-line imaging studies in cases of abdominal pathology.