Determination of Factors to Distinguish MIS-C from Acute Appendicitis in Children with Acute Abdominal Pain.

Abstract

The aim of this study was to make the differential diagnosis between acute appendicitis and multisystem inflammatory syndrome in children (MIS-C) for patients presenting with the complaint of acute abdominal pain (AAP) and to identify the determining factors for the diagnosis of MIS-C. Eighty-one children presenting with AAP/suspected AAP were evaluated. Of these, 24 (29.6%) were included in the MIS-C group (MIS-C/g) and 57 were included in the suspected appendicitis group (S-A/g), which consisted of two subgroups: appendicitis group (A/g) and control observation group (CO/g). Comparing MIS-C/g, A/g, and CO/g, duration of abdominal pain (2.4, 1.5, 1.8 days), high-grade fever (38.8, 36.7, 37°C), severe vomiting, and severe diarrhea were higher in MIS-C/g. Lymphocytes count (LC) was lower, while values of C-reactive protein (CRP), ferritin, and coagulopathy were higher in MIS-C/g (p < 0.05). The optimal cutoffs for the duration of abdominal pain was 2.5 days; the duration of fever, 1.5 days; peak value of fever, 39°C; neutrophil count, 13,225 × 1,000 cell/µMoL; LC, 600 × 1,000 cell/µMoL; ferritin, 233 µg/L; and D-dimer, 16.4 mg/L (p < 0.05). The optimal cutoff for CRP was 130 mg/L (sensitivity 88.9, specificity 100%, positive predictive value 100%, NPV, negative predictive value 92.5%, p < 0.001). All patients in MIS-C/g tested positive by serology by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The duration of abdominal pain, presence of high-grade and prolonged fever, and evaluation of hemogram in terms of high neutrophil count and low LC exhibit high sensitivity and negative predictive value for MIS-C presenting with AAP. In case of doubt, inflammatory markers such as CRP, ferritin, D-dimer, and serology for SARS-CoV-2 should be studied to confirm the diagnosis.