BACKGROUND: Obesity is associated with substantial thromboembolic risk, however, no standard laboratory method exists to stratify risk for post-operative thrombotic events. Our aim is to evaluate preoperative pro-thrombotic biomarkers and thromboelastometry in relationship to clinical VTE stratification in bariatric patients.

METHODS: Preoperative blood samples were assessed for rotational thromboelastometry, D-Dimer, C-Reactive Protein (CRP), Plasminogen Activator Inhibitor-1 (PAI-1), von Willebrand factor (vWF), and P-selectin, and compared to 50 normal control (NC) samples. Patients were stratified into Caprini Risk Score (CRS) groups: moderate (3-4), high (5-8), and very high (>8) VTE risk.

RESULTS: One hundred bariatric patients were assessed and risk stratified to CRS 3-4 (n=23), CRS 5-8 (n=67), and CRS >8 (n=10). D-dimer, PAI-1, and CRP were increased compared to NC, all p< 0.001, P-selectin and vWF demonstrated no differences compared to NC. D-dimer demonstrated significant differences between moderate, high, and very high-risk groups (all p <0.05) and positive correlation with CRS (r =0.44, p<0.001). On thromboelastometry, clot formation time (CFT) was faster than normal in 18% of patients, with maximum clot firmness (MCF) higher than normal in 54% of patients. No difference was found comparing thromboelastometry between CRS groups. Significant correlations were found between CRP and CFT (r= -0.44), α-angle (r=0.40) and MCF (r= 0.44) all p<0.05 respectively. D-dimer negatively correlated with CFT (r= -0.34, p<0.05), and clotting time (r=-0.78, p<0.05) in very high-risk patients.

CONCLUSION: Preoperative D-dimer and CRP are significantly increased in bariatric patients and correlate with prothrombotic features on thromboelastometry. No significant differences were found comparing viscoelastic tests among CRS groups , which suggests patients with marked prothrombotic findings are not being differentiated into higher risk categories by clinical assessment alone.