Surgeon General's Workshop on Deep Vein ThrombosisDIAGNOSIS OF VTE1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 Structured clinical assessment
Objective testing
SLIDE 2: STRUCTURED CLINICAL ASSESSMENT Risk factors Symptoms and signs Alternative diagnosis SLIDE 3: ASSESSING PRETEST PROBABILITY OF FIRST DVT
Low = 0; moderate 1-2; high = 3 SLIDE 4: Traditional Objective Tests Reference standard tests are expensive, invasive and require contrast Photo of DVT: Venography Photo of PE: Pulmonary Angiography SLIDE 5: OBJECTIVE TESTING FOR DVT D-dimer Compression ultrasonography Venography Degradation product of cross-linked fibrin Assayed in plasma or whole blood Sensitivity over 95%, but specificity only 65% Test has high negative predictive value Photo of SimpliRED D-dimer
SLIDE 8: Compression ultrasonography (CUS) Sensitivity and specificity over 95% for symptomatic proximal DVT Sensitivity and specificity of 60 to 70% for isolated symptomatic calf DVT SLIDE 9: Compression Ultrasonography (CUS) Photo of Compression Ultrasonography (CUS) SLIDE 10: SUSPECTED DVT PRETEST PROBABILITY Flowchart of suspected DVT Pretest Probability: Patients with a low pretest probability of DVT should undergo D-dimer testing. If the D-dimer is negative, the risk of DVT is sufficiently low that further diagnostic testing is unnecessary. If the D-dimer is positive, CUS should be performed. A positive CUS establishes the diagnosis of DVT, whereas a negative test makes the diagnosis unlikely. Those with a moderate or high pretest probability, where the prevalence of DVT is 33% and 85%, respectively, should proceed directly to CUS because a negative D-dimer cannot reliably exclude the diagnosis. A negative CUS in these patients does not exclude the possibility of calf DVT and a D-dimer test is helpful. A negative D-dimer makes calf DVT unlikely, whereas a positive test warrants repeat CUS in one week or sooner if symptoms progress. SLIDE 11: AREAS OF CONTROVERSY Calf DVT Recurrent DVT Structured clinical assessment Objective testing
SLIDE 13: OBJECTIVE TESTING FOR PE D-dimer CT angiography (or V/Q) MR angiography SLIDE 14: CT Pulmonary Angiography (CTPA) Photo of CT Pulmonary Angiography (CTPA) SLIDE 15: SUSPECTED PE PRETEST PROBABILITY Flowchart of suspected PE Pretest Probability: Patients with a low pretest probability of PE should undergo D-dimer testing. A negative D-dimer excludes the diagnosis, whereas a positive test should prompt CTPA. Ventilation-perfusion lung scanning or MR angiography can be used in place of CTPA in patients with impaired renal function. Patients with a moderate or high pretest probability should proceed directly to CTPA. A positive test establishes the diagnosis. Those with a negative or indeterminate test should undergo bilateral CUS and D-dimer testing. A positive CUS establishes a diagnosis of VTE. If CUS and D-dimer are both negative, the diagnosis is excluded. If CUS is negative, but the D-dimer test is positive, CUS should be repeated in one week. |
