(74) Development of an Ultrasound-based Severity Score for Pediatric Appendicitis and Comparison to Intra-operative Severity Grade

Background: Appendicitis is a common surgical emergency often seen in pediatric patients, for which ultrasound (US) is the initial imaging modality of choice. Although previous research has shown US to be a reliable modality for diagnosis of appendicitis, it remains to be seen whether or not it alone can be used to set expectations regarding anatomic severity and/or post-operative outcomes.

Objectives: To our knowledge, there are no objective systems using only US for these predictions. Such a system would be especially useful in pediatric patients, as appendicitis in this population presents more variably than in adults and missed diagnoses account for a significant burden to patients and healthcare systems. We developed a system of grading US findings from 0 to 5 for this purpose and designed it to complement the AAST anatomic severity grading system.

Design/Methods: Single institution multi-site retrospective review including 268 patients < 18 years of age who received a trans-abdominal pre-operative US and an appendectomy within the next 72 hours. An US severity scoring system (USSSS) was developed based on a priori defined criteria (Table 1), with scores ranging from 0 to 5. Radiologist reports were analyzed by two independent reviewers and USSSS scores were assigned. Primary outcomes were AAST grade (Table 1), length of post-operative hospital stay and Clavien-Dindo grade and rate of complication severity.

Results: Among 268 patients, the USSSS score distribution was Grade 0 (n=61, 22.76%), 1 (n=46, 17.16%), 2 (n=62, 23.13%), 3 (n=95, 35.45%), 4 (n=3, 1.12%) and 5 (n=1, 0.37%). There were no statistically significant correlations between USSSS and key post-operative outcomes (Figure 1; Kendall’s Tau b correlation coefficient 0.046) unless the system was simplified into two categories to mirror complicated and uncomplicated appendicitis status (Figure 2). AAST severity was closely correlated with key post-operative outcomes (Figure 3; Kendall’s Tau b correlation coefficient 0.701).

Conclusions: Higher USSSS scores do not correlate to increased length of stay, AAST score or Clavien-Dindo complication grade or complication rate unless simplified to designate cases as complicated vs. uncomplicated. Increasing AAST grade does correspond with increasing severity of these key post-operative outcomes. This suggests that while US is able to predict generally higher or lower expected severity, it is unable to further stratify these expectations.