Purpose: To assess whether calf imaging is necessary to identify patients at risk for developing clinically important pulmonary emboli (PE) or propagation of calf deep venous thrombosis (DVT) when the initial thigh ultrasonographic (US) scan is negative for DVT.
Materials and methods: The authors retrospectively evaluated the radiology reports from 283 patients (168 female and 115 male patients; mean age, 55.7 years; age range, 1-93 years) in whom US was performed to rule out lower extremity DVT. In all patients, the initial thigh examination was negative for DVT. All patients were classified as to the reason for the examination, risk factors for DVT (including recent surgery), whether they received anticoagulation therapy, and findings on calf US scans. Adverse outcomes were considered a clinically important PE or DVT in the thigh.
Results: Only 1.1% of patients (95% CI = 0.2%, 3.1%) had adverse outcomes. Adverse outcomes occurred only in postsurgical patients (P = .028) and were not related to the presence or absence of calf DVT or method of treatment.
Conclusion: US of the calf is unnecessary at initial evaluation to identify patients at risk of clinically important PE or propagation of DVT into the thigh.