Predictors for Acute Appendicitis in Children.

BACKGROUND: Acute appendicitis in children is the most common condition requiring urgent evaluation and surgery in the emergency department. At times, despite the appendix being seen on ultrasound (US), there can be discrepancy as to whether a patient has clinical appendicitis. Secondary findings suggestive of appendicitis can be helpful in identifying and evaluating these children. OBJECTIVE: The aim of this study was to determine if specific US findings and/or laboratory results are predictive of appendicitis in children with a visualized appendix on US. METHODS: A prospective study was conducted on children (birth to 18 years) presenting to the pediatric emergency department with suspected appendicitis who underwent right-lower-quadrant US. Ultrasound findings analyzed appendix diameter, compressibility, increased vascularity, presence of appendicolith, inflammatory changes, right-lower-quadrant fluid near the appendix, lower abdominal fluid, tenderness during US, and lymph nodes. Diagnosis was confirmed via surgical pathology. RESULTS: There were 1252 patients who enrolled, 60.8 (762) had their appendix visualized, and 39.1 (490) did not. In children where the appendix was seen, 35.2% (268) were diagnosed with appendicitis. Among patients with a visualized appendix, the likelihood of appendicitis was significantly greater if the appendix diameter was 7 mm or greater (odds ratio [OR], 12.4; 95% confidence interval [CI], 4.7-32.7), an appendicolith was present (OR, 3.9; 95% CI, 1.5-10.3), inflammatory changes were seen (OR, 10.2; 95% CI, 3.9-26.1), or the white blood cell (WBC) count was 10,000/µL (OR, 4.8; 95% CI, 2.4-9.7). A duration of abdominal pain of 3 days or more was significantly less likely to be associated with appendicitis (OR, 0.3; 95% CI, 0.08-0.99). The absence of inflammatory changes, WBC count of less than 10,000/µL, and appendix diameter of 7 mm or less had a negative predictive value of 100%. CONCLUSIONS: When the appendix is seen on US but diagnosis of appendicitis is questioned, the absence of inflammatory changes, WBC count of less than 10,000/µL, and appendix diameter of 7 mm or less should decrease suspicion for appendicitis.

Diagnostic accuracy of laboratory and ultrasound findings in patients with a non-visualized appendix.

Ultrasound (US) and laboratory testing are initial diagnostic tests for acute appendicitis. A diagnostic dilemma develops when the appendix is not visualized on US. Objective: To determine if specific US findings and/or laboratory results predict acute appendicitis when the appendix is not visualized. Methods: A prospective study was conducted on children (birth-18 yrs) presenting to the pediatric emergency department with suspected acute appendicitis who underwent right lower quadrant US. Children with previous appendectomy, US at another facility, or eloped were excluded. US findings analyzed: inflammatory changes, right lower quadrant and lower abdominal fluid, tenderness during US exam and lymph nodes. Diagnoses were confirmed via surgical pathology. Results 1252 subjects were enrolled, 60.8% (762) had appendix visualized and 39.1% (490) did not. In children where the appendix was not seen, 6.7% [33] were diagnosed with appendicitis. Among patients with a non-visualized appendix, the likelihood of appendicitis was significantly greater if: inflammatory changes in the RLQ (OR 18.0, 95% CI 4.5-72.1), CRP >0.5 mg/dL (OR 2.64, 95% CI 1.0-6.8), or WBC > 10 (OR 4.36, 95% CI 1.66-11.58). Duration of abdominal pain >3 days was significantly less likely associated with appendicitis in this model (OR 0.34, 95% CI 0.003-0.395). Combined, the absence inflammatory changes, CRP < 0.5 mg/dL, WBC < 10, and pain, ≤3 days had a NPV of 94.0%. Conclusion When the appendix is not visualized on US, predictors for appendicitis include the presence of inflammatory changes in the RLQ, an elevated WBC/CRP and abdominal pain <3 days.