Is CT the Study of Choice for Pediatric Appendicitis?
Abstract & Commentary
Synopsis: Helical CT with thin collimation is accurate in the diagnosis of appendicitis of children and young adults. CT also is useful in establishing alternative diagnoses in patients who do not have appendicitis.
Source: Sivit CJ, et al. Evaluation of suspected appendicitis in children and young adults: Helical CT. Radiology 2000;216:430-433.
Possible appendicitis is the most common concern of emergency room physicians caring for children with abdominal pain. To avoid unneeded laparotomy and possible missed appendicitis, various imaging modalities have been used for evaluation of the appendix. In the study reported, retrospective review of children presenting with right lower quadrant pain who had a CT was performed. The subjects were 154 patients, 86 girls and 68 boys between the ages of 1-20 years. The patients presented over a three-year period and had a clinical manifestation that was thought equivocal for appendicitis. Patients with unequivocal appendicitis underwent laparotomy.
Helical scanning was performed from the diaphragm to the pubic symphysis and all patients received intravenous contrast medium administered at 3 mL/kg of body weight by using a power injector. Gastrointestinal tract opacification was achieved through oral or rectal administration of 3% diatrizoate meglumine solution. Appendicitis was diagnosed if the appendix did not fill completely with contrast material or air; if it exceeded 6 mm in cross-sectional diameter; or if an appendicolith, adjacent extraluminal air, or a complex fluid collection or mass was noted. Final diagnoses were established by surgical and histopathologic evaluation in 69 patients and by clinical follow-up in 85 patients.
Of the 154 children in the study, 40% were proven to have appendicitis at appendectomy. Results were 58 true-positive diagnoses of appendicitis at CT and six patients with false-positive diagnosis of appendicitis at CT: the appendix diameter was 6.5-7.0 mm or pelvic fluid collections were present, thought to be periappendiceal abscesses. Of 87 patients with true-negative diagnoses at CT, 37% had an alternative diagnosis established on the basis of CT findings. There were three false-negative diagnoses at CT in patients with surgically proven appendicitis.
The high diagnostic accuracy of CT emphasizes the effectiveness of this examination. The use of thin collimation is recommended throughout the abdomen and the pelvis and rectal contrast may be more effective than oral contrast material.
Comment by Beverly P. Wood, MD
Of children presenting with acute abdomen and possible appendicitis, only about one-third have appendicitis. Laparotomy in the absence of appendicitis or delay in the case of appendicitis needs to be kept to a minimum. Cost of observation of equivocal cases is prohibitive; thus, establishing the diagnosis at the time of the emergency workup is ideal. To date, ultrasonography with graded pressure has been found to be accurate, although often inconclusive in very young children. CT is useful with few false-positive or false-negative examinations, and avoids unnecessary surgery or missed appendicitis. The accuracy of CT in children is the same as that in adults, and the studies are not more difficult to perform and interpret than in the adult age group. CT is effective in identifying other causes of abdominal pain in the presence of a negative appendix. Rectal contrast and thin collimation imaging of the lower abdomen and pelvis as well as evaluation of the entire abdomen increase the accuracy of the examination. Unfortunately, this study does not compare modalities, so it is not possible to determine how often CT alone accurately made the diagnosis as contrasted with ultrasound examination.
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