Purpose or Case Report: To assess the validity and appropriatness of the diagnostic pathway that suggests clinical evaluation, primary use of US and staged limited CT for evaluation of children with suspected appendicitis
Methods & Materials: Retrospective review of the electronic medical records of 206 consecutive children who presented to our ER department with acute abdominal pain and underwent US examination for suspected appendicitis. The imaging findings, management plan, and surgical outcome, if surgery was contemplated, were reviewed. The diagnostic accuracy of US was calculated. The number of CT scans performed and the negative appendectomy rate were also analyzed.
Results: Of the 206 suspected appendicitis cases 68 (33%) had acute appendicitis (AA) at surgery. The appendix was identified on an initial US in 161 (78%) patients (66 (41%) normal, 68 (42.2%) inflamed and 27 (16.8 %) equivocal). CT scan was performed in 4 equivocal cases (2 positive and 2 negative). Surgical confirmation of AA was seen in 57/58 positive sonographic studies with one false positive.
In 45/206 children (20%) the appendix was not identified on the first US. US was repeated in 11/45 cases. The appendix was seen in 10/11 cases (7 normal and 3 inflamed) and was not delineated in 1 case which was inflamed at surgery. Only 5/45 CT scans were performed.
Overall, a normal appendix was visualized in 47 % (66/138) of children on primary US and in 59 % (82/138) on further imaging (US or CT or both). An inflamed appendix was not depicted in 11.7 % of cases on initial US and the non-detection rate dropped markedly to 1.5 % after second US and/or CT. The US was repeated in 24 patients (11.6 %), while CT was performed in 9 cases (4.3%). The ratio of US to CT in our cohort was 23:1. US demonstrated a sensitivity of 93.2 %, specificity of 94.1 %, PPV of 92.1 %, NPV of 94.9 % and accuracy of 93.7 %. The negative appendectomy rate was 2.7%.
Conclusions: US proved reasonably accurate in diagnosing acute appendicitis and should be validated as the primary imaging modality in children with suspected appendicitis. The diagnostic strategy of repeating the US in equivocal cases and limiting the use of CT scans to cases were US fails to identify the appendix or remains equivocal despite a second examination, results in reasonable negative appendectomy rate and offers the opportunity to substantially reduce radiation.