Background/Purpose: To assess the additive value of magnetic resonance imaging (MRI) in the setting of an equivocal US (Eq-US) with or without an elevated absolute neutrophil count (ANC). Methods: Single-institution, retrospective review of children ages 5–18 years who presented to the ER with suspected appendicitis from 9/2015 to 8/2016. US, ANC, and MRI results were reviewed. Imaging was identified as positive/suspicious, normal, or equivocal and ANC < 8000/mm3 was defined as normal. Results: 738 patients with a median age of 11 years (IQR 8–14) met inclusion criteria. US was equivocal in 61.4%. Among 304 (67.1%) patients with an Eq-US and normal ANC, only 5 (1.6%) had acute appendicitis. In contrast, 28 of 149 patients (18.8%) with Eq-US and elevated ANC had appendicitis. MRI was performed in 125 patients with Eq-US and was positive/suspicious in 2.9% (2/69) with normal ANC and 25.0% (14/56) with elevated ANC. MRI had 94.7% sensitivity and 100% specificity for acute appendicitis in patients with an Eq-US. Conclusions: MRI has high sensitivity and specificity for diagnosing acute appendicitis in children. Patients with Eq-US plus a normal ANC have a very low likelihood of appendicitis and do not typically require further imaging. MRI may have utility for children with Eq-US and elevated ANC. Level of Evidence: Level III.
- Absolute neutrophil count
- Equivocal ultrasound
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health