Asymmetry of the calves in the assessment of patients with suspected acute pulmonary embolism.

PURPOSE

The purpose of this investigation was to evaluate measured asymmetry of the calves in the assessment of patients with suspected pulmonary embolism (PE).

METHODS

Patients randomized for pulmonary angiography in the collaborative study of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) were evaluated. Only patients in whom the circumference of the calves was measured were included in this evaluation of PIOPED data. Among these, 232 had angiographically diagnosed PE and 446 had no PE by angiography. For purposes of comparison, measurements of the calves also were made in a nonrandomized current cohort of 101 healthy subjects. All calf measurements were made 10 cm below the tibial tuberosity.

RESULTS

Asymmetry in the circumference of the calves of 1 cm or more was measured in 101 of 232 or 44% (95% confidence interval [CI], 37 to 51%) with PE, 176 of 446 or 39% (95% CI, 34 to 44%) without PE, and in 6 of 101 or 6% (95% CI, 1 to 11%) control subjects (PE vs control subjects, p < 0.001; subjects without PE vs control subjects, p < 0.001; PE vs no PE, p = NS). Among patients with PE, the addition of calf asymmetry of 1 cm or more to qualitative signs of deep venous thrombosis increased the prevalence of a detectable abnormality of the lower extremities from 62 of 232 or 27% (95% CI, 21 to 33%) to 129 of 232 or 56% (95% CI, 49 to 63% [p < 0.001]).

CONCLUSION

Asymmetry of the calves of 1 cm or more is abnormal. Such asymmetry of the calves did not distinguish between patients with PE and those with no PE. When considered in proper perspective with other nonspecific signs and symptoms in patients with suspected acute PE, however, subtle calf asymmetry may call attention to the possibility of thromboembolic disease. The observation of subtle asymmetry may indicate a need for noninvasive diagnostic tests of the lower extremities to determine whether deep venous thrombosis is present.