Further studies are needed, however, to determine whether this test could serve as the sole diagnostic tool in patients with a high pretest probability of DVT, coauthor Dr. Scott M. Stevens, from Intermountain Medical Center, Murray, Utah, and colleagues note.
Searching MEDLINE, EMBASE, and other sources, Dr. Stevens’ team identified six prospective cohort studies and one randomized controlled trial that assessed 90-day DVT rates in 4731 patients who had negative whole-leg CUS studies and who did not receive anticoagulation.
Nearly 14% of patients had an active malignancy and 15.3% had undergone major surgery. Four studies focused solely on ambulatory patients, two on both ambulatory and hospitalized patients, and one on just hospitalized patients.
Thirty-four patients (0.7%) developed venous thromboemboli (VTE) or had a suspected VTE-related death. Eleven of these 34 had distal DVT, 7 had proximal DVT, 7 had nonfatal pulmonary emboli, and 9 died from a possible VTE cause.
The authors calculate that with a random effects model and inverse variance weighting, the combined VTE rate at 3 months was 0.57%.
A separate study, reported in The American Journal of Medicine for February, suggests that anticoagulants can probably be safely withheld from inpatients with a negative whole-leg (non-compression) ultrasound result – although up to 3.5% of inpatients may develop VTE in the next 3 months.
In this study, coauthor Dr. Jose Labarere, from Grenoble University Hospital, France, and associates assessed thromboembolism rates in 513 inpatients with clinically suspected DVT and a negative whole-leg ultrasound result who were followed for 3 months.
Three patients (0.6%) experienced a nonfatal symptomatic VTE event and an additional seven patients (1.3%) died from causes possibly related to pulmonary embolism.
Further research, the authors note, is needed to determine if single whole-leg ultrasound and serial compression ultrasound of the proximal veins “are equivalent strategies for ruling out suspected DVT in inpatients,” the researchers conclude.
Am J Med 2010;123:158-165.