DVT may not be related to development of pulmonary embolisms

Pulmonary embolisms may occur de novo in the lungs rather than originate from the pelvic or proximal lower extremity veins, according to the results of a retrospective study. This finding challenges the commonly held belief that there is an association between the two diseases.

Researchers from Massachusetts General Hospital and Harvard Medical School in Boston examined data from 247 trauma patients who underwent computed tomographic pulmonary angiography with computed tomographic venography from January 2004 to December 2006.

Nineteen percent of patients had pulmonary embolism and 7% had deep vein thrombosis.

Among patients with pulmonary embolism, 39% had central pulmonary embolism involving the main or lobar pulmonary arteries and 61% had peripheral pulmonary embolism involving the segmental or subsegmental branches.

Among patients with DVT, the most proximal extension of the clot was observed in the iliac vein in two patients, in the femoral vein in nine and in the popliteal vein in seven.

Fifteen percent of patients who had DVT also had pulmonary embolism. No differences were observed for variables including age, sex and mortality type between patients with pulmonary embolism and DVT and those without DVT.

“Based on these data, there is little evidence that pulmonary embolism originates from DVT of peripheral veins,” the researchers said in a press release. “We propose that many pulmonary embolisms form primarily in the lungs and that the risk-benefit ratio of vena cava filters should be reconsidered.”

However, in an accompanying editorial, Raul Coimbra, MD, PhD,wrote, “The lack of a control comparison for computed tomographic venography is a significant limitation of the study.”

“Although intriguing, their hypothesis cannot be confirmed by these data,” said Coimbra, chief, division of trauma, surgical critical care and burns, University of California, San Diego. “As a well-written and provocative article should be, it raises more questions than it answers.”

Velmahos GC. Arch Surg. 2009;144:928-932.