The association between abdominal ultrasound findings and clinical severity in MIS-C children with extracardiac symptoms

This study aimed to evaluate pathological findings on abdominal ultrasonography upon admission of children diagnosed with Multisystem Inflammatory Syndrome in Children (MIS-C) that were associated with a more severe disease course and the need for intensive care unit (ICU) admission. This retrospective and observational study was conducted between March 2020 and May 2022. Abdominal ultrasonography findings were evaluated in children diagnosed with MIS-C associated with SARS-CoV-2. Ultrasound examinations were conducted within the first 24 h following hospital admission. Clinical severity was categorized as mild-moderate or severe based on the highest clinical severity score observed at any point during hospitalization, using the criteria of dehydration, oxygen or inotropic requirements, cardiac involvement, and respiratory support. The indications of ICU admission were decreased ejection fraction, pulmonary involvement, and any signs of shock. We compared the presence of any individual ultrasonography findings with clinical severity and the need for ICU admission. Multivariable logistic regression analysis was performed to identify independent sonographic predictors of clinical severity and ICU admission. A total of 70 children were included in the study, 16 of whom (23%) were categorized as having severe diseases. ICU admission was required for 14 children (20%), 13 of whom had severe disease. Notably, three children with severe clinical scores did not require ICU admission. The most common ultrasonography findings were intra-abdominal free fluid (41%), hepatomegaly (36%), splenomegaly (33%), mesenteric inflammation (21%) and mesenteric lymphadenopathy (%19). Intra-abdominal free fluid (p < 0.001; OR = 18.20; 95% CI, 3.69-89.86), mesenteric inflammation (p < 0.001; OR = 10.29; 95% CI, 2.80-37.83), mesenteric lymphadenopathy (p = 0.007; OR = 6.22; 95% CI; 1.69-22.88), and hepatosplenomegaly (p = 0.039; OR = 3.89; 95% CI, 1.15-13.17) were substantially associated with severe clinical outcomes. Intra-abdominal free fluid (p < 0.001; OR = 13.76; 95% CI, 2.77-68.29) and hepatosplenomegaly (p = 0.002; OR = 8.00; 95% CI, 2.19-29.25) were significantly more common in children who required ICU admission. Multivariable logistic regression analysis revealed that intra-abdominal free fluid was an independent predictor of severe disease (p = 0.026; OR = 7.41; 95% CI, 1.28-43.00) and ICU admission (p = 0.007; OR = 9.80; 95% CI, 1.88-51.04). Conclusion: Abdominal ultrasonography findings may indicate clinical severity in children with MIS-C. Intra-abdominal free fluid strongly correlates with severe clinical outcomes and the need for intensive care. What is Known: center dot Abdominal ultrasonography findings in children with MIS-C are non-specific and include intra-abdominal free fluid, mesenteric lymphadenopathy, and hepatosplenomegaly. center dot MIS-C is associated with significant systemic inflammation and can present with a variety of extracardiac symptoms, often overlapping with acute abdominal conditions. What is New: center dot Intra-abdominal free fluid on ultrasonography is strongly associated with severe clinical outcomes and the need for ICU admission in MIS-C patients center dot This study identifies intra-abdominal free fluid as an independent sonographic predictor of disease severity and intensive care needs, emphasizing the importance of early abdominal ultrasonography in MIS-C management.