Clots traveling from lower veins may not be the cause of pulmonary embolism in trauma patients

Oct 19, 2009

A report from a team of Massachusetts General Hospital (MGH) physicians calls into question the longstanding belief that pulmonary embolism (PE) - the life-threatening blockage of a major blood vessel in the lungs - is caused in trauma patients by a blood clot traveling from vessels deep within the legs or lower torso. In their study utilizing advanced imaging technologies, which appears in the October Archives of Surgery, the MGH investigators found no evidence of deep venous thrombosis (DVT) in most trauma patients with pulmonary embolism.

"A consistent finding of previous studies - which was often overlooked - was that no lower-extremity vein clots were found in patients suffering ," says George Velmahos, MD, PhD, chief of the MGH Division of Trauma, Emergency Surgery, and Surgical Critical Care, who led the study. "But our surgical minds were so stuck in the dogma that PE originates from lower-extremity DVT that even though the data was there, we didn't pay attention to it."

Traditional thinking has been that pulmonary embolism results when a deep venous thrombosis in the legs or pelvis breaks off and travels through the bloodstream into the lungs. If that were true, the authors note, pulmonary embolism patients should still have evidence of the DVT, since part of the original clot would remain attached to the location where it formed. The earlier studies that did not find DVTs in trauma patients with PE had utilized ultrasound imaging, which is limited in its ability to locate deep venous thrombosis, possibly missing any remaining clots.

The current investigation analyzed the results of computed-tomography-based tests - CT pulmonary angiograms for the lungs and for the lower extremities CT venography, which is highly accurate in diagnosing clots in major blood vessels. The researchers reviewed the records of 247 trauma patients who had received both CT pulmonary angiograms and CT venograms at MGH from 2004 through 2006. While 46 patients developed pulmonary embolism and 18 had , only 7 of the 46 PE patients also had evidence of DVT. The known accuracy of CT venograms make it highly unlikely, the authors note, that many patients had undetected DVTs.

This report - believed to be the first to express doubts about the accepted origin of pulmonary embolism - needs to be confirmed by other investigators and also cannot be extrapolated to the rare instances when PE develops in otherwise healthy individuals. The authors' hypothesis - yet to be tested - is that clots may form independently in the lungs, and if the study's results hold up, they would imply that current measures to prevent PE - including blood-thinning drugs, mechanical compression of the legs and the insertion of filters into the major vein that carries blood from the lower extremities - are not effective.

"If it turns out that clots are forming primarily in the lungs, it would revolutionize the way we think about PE and they way we prevent and treat it," says Velmahos, who is the John Francis Burke Professor of Surgery at Harvard Medical School.

Source: Massachusetts General Hospital (news : web)

Explore further: Beware of claims about cosmetic stem cells procedures, review says

add to favorites email to friend print save as pdf

Related Stories

Study examines long-term outcomes following blood clots

Feb 25, 2008

Patients who develop a blood clot in their legs (deep vein thrombosis) or lungs (pulmonary embolism) are at risk for experiencing another blood clot within three years, and patients with pulmonary embolism have a higher risk ...

Belt and braces approach may prevent deep vein thromboses

Oct 08, 2008

Combining short periods of leg compression with medications such as heparin is more effective at preventing blood clots in high-risk patients than using either preventative measure alone. A team of Cochrane Researchers believe ...

Ultrasound waves aid in rapid treatment of DVT

Nov 23, 2008

The use of ultrasound waves for deep vein thrombosis (DVT) may help dissolve blood clots in less time than using clot-busting drugs alone, according to researchers at Emory University. The study will be presented Sunday, ...

New no-needle approach to prevent blood clots

Aug 11, 2009

The dean of the University of Oklahoma College of Public Health and a team of scientists worldwide have found a better way to prevent deadly blood clots after joint replacement surgery - a major problem that ...

Minor leg injuries associated with risk of blood clots

Jan 14, 2008

Muscle ruptures, ankle sprains and other common minor leg injuries appear to be associated with a higher risk for blood clots in the legs or lungs, according to a report in the January 14 issue of Archives of Internal Medicine, ...

Recommended for you

New malaria vaccine candidates identified

7 hours ago

Researchers have discovered new vaccine targets that could help in the battle against malaria. Taking a new, large-scale approach to this search, researchers tested a library of proteins from the Plasmodium fa ...

User comments : 0