Surgeon-Performed Ultrasound Effective Screen for DVT
Surgeon-Performed Ultrasound Effective Screen for DVT
Yael Waknine
March 9, 2004 — Surgeon-performed ultrasound examination was found to be a rapid and accurate screening tool for the presence of deep vein thrombosis (DVT) in the common femoral veins (CFV) of critically ill patients, according to a prospective study published in the March issue of the Archives of Surgery.
"Despite the administration of prophylactic agents, asymptomatic DVT continues to occur in high-risk, critically ill patients," write Grace S. Rozychi, MD, RDMS, and colleagues, from the Department of Surgery at the Emory University School of Medicine, Grady Hospital, in Atlanta, Georgia. "DVT, with its potential complications, significantly increases morbidity and mortality for [these patients]."
The authors add, "A variety of risk factors in the critically ill patient contribute to the development of DVT, and this limits the effectiveness of current preventive options. Considering these issues, the early administration of prophylactic agents and routine screening for occult DVT have merit."
During a 16-month period, 220 critically ill patients at high risk for DVT underwent 306 ultrasound examinations to detect the presence of DVT in the CFV. Patients were examined daily and received appropriate doses of unfractionated or low-molecular-weight heparin.
Focused ultrasound was performed by two experienced surgeon-sonographers at a mean of every 3.5 ± 2.8 days (range, 1 - 4 days). Procedure time was 2.0 ± 0.3 minutes (range, 1.8 - 4.0 minutes). Color-flow duplex imaging studies were then performed within four days of the ultrasound, at a mean of every 6.3 ± 2.0 days (range, 4 - 7 days).
Comparisons of ultrasound results with those of the duplex studies were classified as true-negative (n = 295), true-positive (n = 9), false-negative (n = 1), and false-positive (n = 1) results, yielding 90.0% sensitivity, 99.6% specificity, and 99.3% accuracy for the ultrasound readings.
The high rate of true-negative results was likely a reflection of DVT prophylaxis administered to all patients, the authors comment. However, "[b]ecause so few patients manifest findings consistent with DVT on their physical examinations, screening tests are not only worthwhile but necessary for early detection and treatment," the authors point out.
The most likely cause of the false-negative result is the weak echogenicity of a fresh thrombus, precluding its visualization, according to the authors. The false-positive result was thought to be due to abundant adipose tissue and muscle in the patient's thigh, which made it difficult to compress the CFV. "For patients with this body habitus, other diagnostic studies, such as the radioactive fibrinogen uptake study, may be needed," the authors explain.
"Although our focused ultrasound examination is not as detailed as the more time-consuming duplex imaging study, it accurately detects CFV thrombosis and rapidly screens for DVT," the authors conclude. "We recommend that surgeons use this focused ultrasound examination to initially screen high-risk surgical patients for occult CFV thrombosis as well as to examine those patients in whom pulmonary embolism is strongly suspected."
The authors report no financial conflicts of interest.
Arch Surg. 2004;139:375-280
Reviewed by Gary D. Vogin, MD
Yael Waknine is a freelance writer for Medscape.
Yael Waknine
March 9, 2004 — Surgeon-performed ultrasound examination was found to be a rapid and accurate screening tool for the presence of deep vein thrombosis (DVT) in the common femoral veins (CFV) of critically ill patients, according to a prospective study published in the March issue of the Archives of Surgery.
"Despite the administration of prophylactic agents, asymptomatic DVT continues to occur in high-risk, critically ill patients," write Grace S. Rozychi, MD, RDMS, and colleagues, from the Department of Surgery at the Emory University School of Medicine, Grady Hospital, in Atlanta, Georgia. "DVT, with its potential complications, significantly increases morbidity and mortality for [these patients]."
The authors add, "A variety of risk factors in the critically ill patient contribute to the development of DVT, and this limits the effectiveness of current preventive options. Considering these issues, the early administration of prophylactic agents and routine screening for occult DVT have merit."
During a 16-month period, 220 critically ill patients at high risk for DVT underwent 306 ultrasound examinations to detect the presence of DVT in the CFV. Patients were examined daily and received appropriate doses of unfractionated or low-molecular-weight heparin.
Focused ultrasound was performed by two experienced surgeon-sonographers at a mean of every 3.5 ± 2.8 days (range, 1 - 4 days). Procedure time was 2.0 ± 0.3 minutes (range, 1.8 - 4.0 minutes). Color-flow duplex imaging studies were then performed within four days of the ultrasound, at a mean of every 6.3 ± 2.0 days (range, 4 - 7 days).
Comparisons of ultrasound results with those of the duplex studies were classified as true-negative (n = 295), true-positive (n = 9), false-negative (n = 1), and false-positive (n = 1) results, yielding 90.0% sensitivity, 99.6% specificity, and 99.3% accuracy for the ultrasound readings.
The high rate of true-negative results was likely a reflection of DVT prophylaxis administered to all patients, the authors comment. However, "[b]ecause so few patients manifest findings consistent with DVT on their physical examinations, screening tests are not only worthwhile but necessary for early detection and treatment," the authors point out.
The most likely cause of the false-negative result is the weak echogenicity of a fresh thrombus, precluding its visualization, according to the authors. The false-positive result was thought to be due to abundant adipose tissue and muscle in the patient's thigh, which made it difficult to compress the CFV. "For patients with this body habitus, other diagnostic studies, such as the radioactive fibrinogen uptake study, may be needed," the authors explain.
"Although our focused ultrasound examination is not as detailed as the more time-consuming duplex imaging study, it accurately detects CFV thrombosis and rapidly screens for DVT," the authors conclude. "We recommend that surgeons use this focused ultrasound examination to initially screen high-risk surgical patients for occult CFV thrombosis as well as to examine those patients in whom pulmonary embolism is strongly suspected."
The authors report no financial conflicts of interest.
Arch Surg. 2004;139:375-280
Reviewed by Gary D. Vogin, MD
Yael Waknine is a freelance writer for Medscape.
