A team from Springfield, Massachusetts, USA, determined the accuracy of CT and ultrasonography (US) in diagnosing appendicitis, in adults stratified to either modality on the basis of body mass index (BMI).
A total of 72 adults with suspected appendicitis and demonstrating atypical clinical features were included in the study.
Patients with a BMI less than 30 underwent US. Those with a BMI ≥ 30 underwent CT.
Surgery, medical record, and clinical follow-up after 3 months determined outcomes.
Of the 72 patients enrolled, 30 (24 women and 6 men) underwent CT and 42 (35 women and 7 men) underwent US.
The average BMI was 34 among patients who had CT and 24 among patients who had US.
Of the patients who had CT scans, 4 had positive scans for appendicitis and all of these were proven at surgery to have appendicitis.
The remaining 26 patients had negative CT scans for appendicitis. Twenty-two of these were subsequently proven either by surgery or clinical follow-up not to have appendicitis, while 4 were lost to follow-up.
|CT accurately evaluated appendicitis in those with BMI ≥ 30.|
| Emergency Radiology |
This corresponded to a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100 %.
Twelve ultrasound examinations were positive for appendicitis. Of these patients, 9 had appendicitis proven at surgery, 1 had a perforated Meckel's diverticulum, and 2 did not have appendicitis after clinical follow-up.
Some 27 patients had negative ultrasound exams for appendicitis. However, 6 of these had appendicitis proven at surgery, 17 did not have appendicitis, and 4 were lost to follow-up.
Three patients had ultrasound exams that were equivocal for appendicitis; of these, 1 had appendicitis and 2 did not.
For US, this corresponded to a sensitivity of 60 %, specificity of 85 %, PPV of 75 %, and NPV of 74 %.
Dr S. S. Tsai, of the Western Campus of Tufts University School of Medicine, Springfield, concluded on behalf of the group, "This study suggests that CT is an accurate method of evaluating adults with suspected appendicitis who have BMI ≥ 30."
"Stratifying patients with BMI < 30 to US did not reproduce the results already reported in the literature."