Brief ReportThe accuracy of limited B-mode compression technique in diagnosing deep venous thrombosis in lower extremities
Introduction
Deep vein thrombosis (DVT) is prevalent in the emergency departments [1]. Although its accurate prevalence is unknown, it is considered as the reason for hospitalization of about 600 000 patients in the United States. Nearly 60% of untreated DVTs may lead to pulmonary embolism, causing over 50 000 deaths annually [2], [3]. Clinical findings, on their own, are not diagnostic for DVT [4]. Commonly, a complete color-flow duplex ultrasound (CFDU) is the preferable but time-consuming method to detect the condition. The fact that the radiologists or the ultrasound specialists responsible for doing the test are not always readily available in the emergency department, however, has limited their use in emergency cases. Moreover, most cases of pulmonary embolism occur within the first 24 hours [5], [6].
In contrast, carrying out a limited B-mode compression technique (BMCT) (B-mode imaging with direct pressure on the veins and deciding based on the compressibility of the veins) by the emergency medicine specialists in the emergency department both accelerates the pace of diagnosis and treatment and reduces the cost of the treatment [7].
The sensitivity and specificity of BMCT in diagnosing proximal DVT in lower limbs are reported to be between 93% and 100% and 97% and 100%, respectively. Kearon et al [4] found that BMCT had in general a sensitivity of 89%, specificity of 94%, positive predictive value of 94%, and negative predictive value of 90%; these results, however, remarkably improved to values equal to 95%, 96%, 97%, and 98%, respectively, when the test was used to diagnose proximal DVT in the lower limbs.
Cogo et al [6] found that BMCT, which had a sensitivity of 100% in diagnosing proximal DVT, can effectively reduce the time of performance. A sensitivity and specificity of 91% and 99%, respectively, were noted in inpatients having the condition.
Poppiti et al [7] studied BMCT in a group of 72 patients and concluded that the tool has a sensitivity and specificity of 100% and 98%, respectively, in diagnosing DVT. Moreover, the study indicated a substantial reduction in the test time, from 37 minutes for CFDU to 5.5 minutes for BMCT.
In a study performed by Jang et al [8], 8 emergency residents with no experience in diagnosing DVT performed BMCT on 2 normal individuals and 72 patients after participating in a training program consisting of a 1-hour lecture on DVT in the form of a PowerPoint presentation. The mean scan time was 11.7 minutes, and the test was reported to have 100% sensitivity and 91.8% specificity.
The American Radiology Association, however, does not fully agree with the use of compression ultrasound in diagnosing DVT. Frederick et al [9] studied 721 patients presenting with clinical symptoms of lower-limb DVT in a vascular laboratory. As 21% of the studied DVT cases were limited to a single vein (eg, popliteal vein), radiologists concluded that BMCT should not be performed in such population.
The purpose of this study was to compare the sensitivity, specificity, positive predictive value, and negative predictive value of BMCT done by emergency medicine residents with that of CFDU in diagnosing proximal DVT of lower extremities.
Section snippets
Patients and methods
After receiving an approval from the ethical board committee of Tehran University of Medical Sciences, the patients referred to the emergency department of Imam Khomeini Hospital with DVT symptoms, including painful and swollen lower limbs, during a 1-year period in the working shift hours of the researchers were recruited. The cases were selected from among the subjects with no history of chronic DVT as well as those who had never been examined by other diagnostic methods, especially CFDU.
Two
BMCT technique
In the BMCT method, the emergency residents studied 2 vein segments, the iliofemoral and the popliteal veins, in 2 different locations: the iliofemoral segment from saphenofemoral junction up to 10 cm below it and the popliteal segment from saphenopopliteal junction up to tibial vein confluence. Whenever the vein was compressible in these 2 locations, the scan was reported negative. The scan was considered positive for DVT whenever the vein in at least one of these locations was
Results
The prospective study was conducted on 74 patients presenting with the symptoms and signs of lower-limb DVT in the emergency department of Imam Khomeini Hospital. The mean age of patients was 55.16 ± 17.4 years, ranging from 19 to 88 years. About 41 (55.4%) of the patients were men, and 33 (44.6%) were women.
From among the 74 studied patients who underwent BMCT, DVT was diagnosed in 35 patients (47.3%). Color-flow duplex ultrasound performed by a board-certified radiologist, similarly, revealed
Discussion
The present study revealed that CFDU and BMCT have a similar sensitivity, specificity, and accuracy of 100% in detecting proximal DVT. These findings are contrary to the findings of Biondetti et al [10] who compared the sensitivity and specificity of the compression ultrasound with that of venography and reported 87% sensitivity, 100% specificity, and 96% accuracy for the former test. They reported that the 6 isolated distal DVTs of lower limbs, diagnosed by venography, were falsely reported to
Conclusion and suggestions
Our study suggests that the compression ultrasound can be considered as a reasonable alternative to the color Duplex ultrasound for diagnosing proximal DVT in lower extremities. In addition, it showed that short-term training courses for BMCT can effectively teach emergency medicine residents to accurately diagnose proximal DVT in lower limbs. Compared with CFDU, BMCT can be performed easily and rapidly in bedside of those suspicious of having proximal DVT in lower extremities, particularly in
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