Introduction
The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was found to induce an increased incidence of thrombosis1, 2 and strokes3 in adults.  They developed a recognizable coagulopathy, characterized by increased thrombin generation, decreased fibrinolysis, elevated D-dimers and a prolonged prothrombin time (PT), which was found to be a strong predictor of mortality, with pulmonary microthrombi contributing significantly4.  Anticoagulation has been shown to decrease this mortality5.
Rannucci et al 6 reported baseline viscoelastic testing (using the Quantra Hemostasis analyzer system) obtained 2-5 days after admission to the ICU demonstrating increased clot strength, fibrinogen contribution to clot strength and elevated fibrinogen and D-dimer levels in 16 patients. After escalating thromboprophylaxis, there was a significant time-related decrease in fibrinogen, D-dimer levels and clot strength without significant thromboembolic events. Spieza et al 7 used another viscoelastic tool, Rotational Thromboelastometry (ROTEM), in acutely ill hospitalized SARS-CoV-2 patients and demonstrated elevated fibrinogen and D-dimers (p < 0.0001) and higher maximum clot firmness (MCF) in all ROTEM parameters in patients compared to controls (p< 0.0001).
Children develop thromboembolic complications in the face of catheter-related, genetic, anatomical and disease-related predisposing factors. Elevated fibrinogen and D-dimer levels are observed in various conditions in children such as infections and autoimmune diseases, including SARS-CoV-2. However, the prevalence of thromboembolic complications in children with SARS-CoV-2 infection has not been well documented, and there are no pediatric-specific thromboprophylaxis guidelines. Major hematology organizations, including the American Society of Hematology (ASH)8 and the International Society of Thrombosis Haemostasis (ISTH)9 have published recommendations for anticoagulation of hospitalized symptomatic adults with SARS-CoV-2, which have been largely extrapolated to the pediatric population. A recent report by Loi et al10 has made some diagnostic and therapeutic anticoagulation recommendations based on risk stratification of a single institutional experience. However, there remains a need in this population for laboratory-based risk-assessment tools to guide clinical decision making on the use of anticoagulant prophylaxis.
In an effort to explore the utility of viscoelastic testing in children with SARS-CoV-2, we added ROTEM (a viscoelasticity-based tool available for clinical use at our institution) to routine coagulation testing in children admitted with SARS-CoV-2. The objective of this analysis was to determine if standard coagulation tests and ROTEM testing could be obtained in children admitted with SARS-CoV-2 infection to assess its feasibility in determining thrombosis risk. And, if so, were changes in clot strength in children during an acute SARS-CoV-2 infection comparable to that seen in adults. We report our experience in this retrospective analysis of a case series of 8 children with SARS-CoV-2 infection.