P36 – Value of C-reactive protein in predicting abscess in pediatric appendicitis

Author(s):
Katherine Davenport, Timothy Fairbanks, Stephen Bickler, Karen Kling, Mary Hilfiker, Nicholas Saenz, Julia Grabowski, Rady Children

Background: Appendicitis is the most common pediatric surgical emergency. Abscess formation is a frequent complication of appendicitis and can occur both pre-operatively or post-operatively. Though the management of an abscess depends on the clinical situation, its diagnosis typically requires cross- sectional imaging, often a CT scan. In an effort to minimize radiation, exclusion of an abscess with lab markers may mitigate the need for imaging.

Hypothesis: We predict that CRP level correlates with appendicitis-related abscesses.

Methods: We performed a retrospective review of all appendectomies performed for presumed appendicitis from 10/2011-10/2013 in our university practice. We identified patients who had a CT scan and CRP drawn concurrently either pre-operatively or post-operatively. We reviewed demographic data, CT scan findings, and CRP. For those who underwent surgery, we correlated CT findings to pathology and operative details. We compared the weighted mean of CRP of those who had an abscess to those who did not and calculated statistical significance using the rank-sum test.

Results: 1,333 patients underwent appendectomy in this 24 month period. 548 had a CT scan and CRP drawn simultaneously. The average age was 10 years (1-20 years). 56% were male. There were 91 abscesses identified in 87 patients. 61 abscesses were identified pre-operatively, 30 were post-operative. The weighted mean of CRP was significantly higher in those with an abscess (17.0 mg/dL) compared to those without an abscess (6.0 mg/dL), both pre-operatively and post-operatively (p<0.05). Furthermore, of the 91 abscesses recognized, none had a normal CRP.

Conclusions: CRP is significantly higher in the presence of an abscess, both pre-operatively and post-operatively. Additionally, an abscess was never diagnosed in any patient with a normal CRP. CRP value may be helpful in guiding the diagnostic algorithm in patients with a presumed appendicitis-related abscess. A normal CRP level may obviate the need for imaging, thereby reducing radiation exposure in children.