Colour-assisted compression ultrasound in the diagnosis of calf deep venous thrombosis.

OBJECTIVE: To determine sensitivity and specificity of colour-assisted compression ultrasound (CUS) in the diagnosis of deep venous thrombosis (DVT) isolated to the calf veins. DESIGN: Prospective comparison of CUS with contrast venography in patients undergoing both procedures, with blinded evaluation of results. SETTING: Alfred Hospital, Melbourne (an urban tertiary referral hospital), between November 1990 and May 1992. SUBJECTS: Patients presenting for contrast venography with signs or symptoms of lower limb DVT. OUTCOME MEASURES: Presence of DVT; technical adequacy of examination. RESULTS: 92 of 402 patients (104 limbs) were examined. DVT was detected by venography in 43 limbs and was isolated to the calf veins in 19. It was diagnosed by CUS for eight of these 19. Calf CUS was technically inadequate in 26 limbs. Sensitivity and specificity of CUS for isolated calf DVT were 67% (95% confidence interval [CI], 40%-94%) and 93% (95% CI, 83%-100%), respectively, when the CUS was adequate. The low sensitivity of CUS was related to small size of the thrombi, inadequate studies because of previous DVT or very swollen limbs and technical errors. CONCLUSION: CUS is accurate for detecting larger isolated calf DVT when the calf study is adequate. Including the calf veins as well as the femoropopliteal veins in the initial CUS examination for symptomatic suspected lower limb DVT may reduce the need for follow-up CUS.

Comparison of ultrasound and blood pool scintigraphy in the diagnosis of lower limb deep venous thrombosis.

We report a prospective, blinded comparison of compression ultrasound (US) and Tc-99m erythrocyte-labelled venous blood pool scintigraphy (BPS) in patients presenting with symptoms of deep venous thrombosis (DVT). Contrast venography (CV) was used as the gold standard. Ninety-eight lower limbs of 76 patients were examined. DVT was present at CV in 38 of 98 limbs and was isolated to the calf veins in eight. Sensitivity and specificity of ultrasound for femoropopliteal thrombus were 81.5% and 96% and of venous blood pool scintigraphy were 55% and 96%. For deep venous thrombosis in the whole limb sensitivity and specificity of ultrasound were 74% and 90% and of venous blood pool scintigraphy were 61% and 88%. In the calf sensitivity and specificity of US were 61% and 94% and of venous blood pool scintigraphy were 61% and 89%. Excluding equivocal venous blood pool scintigraphy results, the predictive values of a positive and negative venous blood pool scintigraphy study for the whole limb were 84% and 86%. The predictive values of a positive and negative ultrasound where the examination was adequate were 82% and 86%. US is a more sensitive alternative to CV than BPS for femoropopliteal DVT. When neither US nor CV can be performed, BPS remains a useful initial test for DVT, provided it is unequivocally positive or negative.