The Utility of Thromboelastography As a Screening Test for Bleeding Disorders

Accurate assessment of bleeding disorders requires a thorough clinical evaluation and appropriate laboratory testing process. These patients comprise a substantial proportion of consultations carried out by hematologists. The limitations of each screening test, and the heterogeneity of these disorders continue to make the diagnosis cumbersome for the practicing clinician. Plasma clotting times, such as the prothrombin time and activated partial thromboplastin time are the most frequently used screening tests to assess adequacy of hemostasis. Thromboelastography (TEG) lends the ability to assess hemostasis globally while also assessing the effects of platelets, leucocytes and red cells on coagulation.

To determine the utility of TEG as an effective screening test for bleeding disorders

Medical records of patients referred to Hematology Service from August 2006 through July 2011 were retrospectively reviewed after institutional review board approval.

One hundred ninety-five patients (125 females, 70 males: ages 0.1 to 20 years) were evaluated for a bleeding disorder based on either bleeding symptoms or abnormal routine clotting tests and had TEG performed with low dose tissue factor (1:190 000 concentration). Most common symptoms were epistaxis (83/195), bruising (67/195), menorrhagia (48/195), surgical bleeding (16/195). Twenty-nine patients were diagnosed with a bleeding disorder based on clinical evaluation and laboratory testing. Type 1 vonWillebrand disease (vWD) was diagnosed in 16 patients, heterozygous factor VII deficiency in 6 patients, factor XII deficiency in 3 patients, factor XI deficiency in 2 patients and platelet delta storage pool disease in 1 patient. One patient was a symptomatic hemophilia carrier.

Preliminary analysis revealed that among the vWD patients, only 1 patient demonstrated abnormalities in all parameters of TEG [Prolonged Reaction time (R Time), k time (rate of clot formation) and decreased Maximum amplitude (MA)] and 2 showed prolonged R and k time without concomitant decrease in MA. In patients with heterozygous factor VII deficiency, only 2 of 4 patients showed prolonged R and k times. The symptomatic hemophilia carrier, 1 of 3 with factor XII and 1 of 2 patients with factor XI deficiency had prolonged R as their sole abnormality. TEG was completely normal in the patient with platelet delta storage pool disease. The sensitivity of the R time to diagnose a clotting factor (including low factor VIII with vWD) deficiency was only 58% with a specificity of 78%. R time correlated with PTT and PT in up to 50% (vWD: 12%, FVII deficiency: 33%, FXII: 33%, FXI: 50%) of the patients. R time was also prolonged in 46/166 (28%) patients without a definitive bleeding disorder, however 10 of these patients had a lupus anticoagulant.

In our study of 195 patients referred for evaluation of bleeding symptoms or abnormal coagulation tests, TEG was of limited value in identifying congenital coagulation defects with both poor sensitivity and specificity. Future studies could examine different agonists or conditions for TEG that may improve its sensitivity for detection of congenital bleeding disorders.

No relevant conflicts of interest to declare.