A meta-analysis in this week’s JAMA concludes that a negative whole-leg compression ultrasound rules out dangerous outcomes at three months in 99.3% of patients who are not anticoagulated in the interim. This is good news for emergency physicians, at least in patients whose pre-test probability for DVT is low. Unfortunately, it assumes a practice pattern that is more advanced than what is offered in most American centers. The majority of stateside radiology departments do not look at the calf in their rule-out DVT protocol. This policy is based on an outdated and dangerous belief that calf DVTs are benign.
In patients who localize to the calf, ask your radiologist to rule out DVT in the calf as well as the proximal vessels. In patients who are high risk for DVT, anticoagulate empirically; note the major bleeding risk for anticoagulation is 1.1% per year. I am concerned that JAMA readers will mistakenly assume that this paper applies to them and skip anticoagulation, repeat ultrasounds, and other strategies to reduce risk in their query DVT patients whose calves were never evaluated.