Performing single ultrasound to detect blood clot may be sufficient for some patients

February 2, 2010

An analysis of previous studies suggests that for patients with a suspected blood clot in a deep vein of a leg, withholding anticoagulation therapy after a negative whole-leg compression ultrasound is associated with a low risk of developing a blood clot during the subsequent 3 months, suggesting that multiple ultrasounds may not be necessary for some low-risk patients, according to an article in the February 3 issue of JAMA.

Compression ultrasound (CUS) is the primary testing procedure used to diagnose proximal deep vein (DVT; a blood clot in a deep vein in the thigh or leg), as the method confirms and excludes DVT of the proximal (above the knee) but its accuracy for distal vein DVT (below the knee) has been questioned. Up to 25 percent of distal DVTs may move into proximal veins, increasing the risk of pulmonary embolism (blood clot in the veins moving into the lung). "Consequently, practice guidelines recommend serial CUS of the proximal veins 5 to 7 days after an initial negative result to safely exclude clinically suspected DVT. Because only 1 percent to 2 percent of repeat CUS tests detect thrombus propagation, many repeat studies are conducted to detect a small number of DVTs," the authors write.

Whole-leg CUS may exclude proximal and distal DVT in a single evaluation and lessen the need for repeat CUS tests, however concerns exist regarding the safety of using a single whole-leg CUS to exclude DVT following an initially negative result, according to background information in the article.

Stacy A. Johnson, M.D., of the University of Utah School of Medicine, Salt Lake City, and colleagues conducted a review and meta-analysis of previous studies to examine the risk of venous thromboembolism ( in the deep veins of the legs or in the lungs) in patients with suspected lower-extremity DVT following a single negative whole-leg CUS result for whom anticoagulation was withheld. The authors identified seven studies for the analysis, which included 4,731 patients.

An analysis of data indicated that venous thromboembolism or suspected venous thromboembolism-related death occurred in 34 patients (0.7 percent), including 11 patients with distal DVT (32.4 percent), 7 patients with proximal DVT (20.6 percent), 7 patients with nonfatal pulmonary emboli (20.6 percent), and 9 patients (26.5 percent) who died, which may have been related to venous thromboembolism. Use of a model indicated that the combined venous thromboembolism event rate at 3 months was 0.57 percent.

"In summary, withholding anticoagulation following a single negative whole-leg CUS result was associated with a low risk for venous thromboembolism during 3-month follow-up in patients with suspected DVT. Using a single negative whole-leg CUS result as the sole diagnostic modality in patients with high pretest probability of DVT requires further study," the authors conclude.

More information: JAMA. 2010;303[5]:438-445.

Related Stories

Recommended for you

Study finds walnuts may promote health by changing gut bacteria

July 28, 2017
Research led by Lauri Byerley, PhD, RD, Research Associate Professor of Physiology at LSU Health New Orleans School of Medicine, has found that walnuts in the diet change the makeup of bacteria in the gut, which suggests ...

Green tea ingredient may ameliorate memory impairment, brain insulin resistance, and obesity

July 28, 2017
A study published online in The FASEB Journal, involving mice, suggests that EGCG (epigallocatechin-3-gallate), the most abundant catechin and biologically active component in green tea, could alleviate high-fat and high-fructose ...

Manipulating a type of brain cell gets weight loss results in mice

July 28, 2017
A new study has found something remarkable: the activation of a particular type of immune cell in the brain can, on its own, lead to obesity in mice. This striking result provides the strongest demonstration yet that brain ...

Team finds link between backup immune defense, mutation seen in Crohn's disease

July 27, 2017
Genes that regulate a cellular recycling system called autophagy are commonly mutated in Crohn's disease patients, though the link between biological housekeeping and inflammatory bowel disease remained a mystery. Now, researchers ...

Study finds harmful protein on acid triggers a life-threatening disease

July 27, 2017
Using an array of modern biochemical and structural biology techniques, researchers from Boston University School of Medicine (BUSM) have begun to unravel the mystery of how acidity influences a small protein called serum ...

CRISPR sheds light on rare pediatric bone marrow failure syndrome

July 27, 2017
Using the gene editing technology CRISPR, scientists have shed light on a rare, sometimes fatal syndrome that causes children to gradually lose the ability to manufacture vital blood cells.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.