Keywords
deep vein thrombosis - emergency medicine doctor - radiologist - two-point compression
ultrasound
Introduction
Venous thromboembolism (VTE) is a serious coagulation disorder that includes deep
vein thrombosis (DVT) and pulmonary embolism. Rapid and accurate detection of DVT
is important in emergency medicine to prevent a fatal disease such as pulmonary embolism.[1] Although DVT is frequently seen in the lower extremity veins, it can occur in the
entire venous system. Thrombosis in the deep venous system of the extremities may
cause symptoms such as pain, swelling, redness, and diameter difference in the acute
phase of the disease. The Wells score for diagnosing DVT is one of the most commonly
tested scores to determine the probability of disease. However, it has recently been
modified due to problems in using the Wells score. Modified Wells score can be applied
to patients whose clinical presentation is concerning for a DVT for risk stratification.
Physicians recommend additional testing at values of 2 and above in calculating this
score.[2]
[3] Considering DVT, the Wells score is the most well-known and is used to determine
probability and classify patients with suspected DVT.[2]
[3]
In addition to probability classifications, another tool used in the diagnostic process
is 'D-dimer,' a fibrin degradation product. However, history, physical examination,
probability classifications, and biochemical parameters such as d-dimer are only guides
in the process leading to the diagnosis, and more is needed to make the final diagnosis.
The definitive diagnosis of DVT in the emergency department (ED) is made by lower
extremity venous USG. Duplex USG of the lower extremity (color and flow Doppler USG)
and compression USG is an imaging method that is non-invasive and has a high diagnostic
value.[4]
[5]
It is listed as one of the basic emergency ultrasonography applications in the emergency
ultrasonography guidelines of the American College of Emergency Physicians and has
been widely used by many emergency physicians in recent years. It can be applied quickly
at the bedside as it is easy to apply and promptly guide the appropriate treatment.
In this application, the simplified two-point compression technique focuses on evaluating
the lower extremity's common femoral and popliteal vessels for complete compression.[2]
[4]
[5] Two-point compression USG is an ideal diagnostic tool for emergency practice because
it is a fast, effective, easy-to-apply, and noninvasive procedure.[6] In departments where patient flow is fast and intense, such as the ED, evaluating
patients as quickly as making the correct diagnosis is important. Steps such as transferring
the patient to the radiology department and reporting the USG prolong the patient's
diagnosis process. Bedsides, USG performed by emergency doctors may shorten the diagnosis
time of patients with the possibility of DVT.[7] This study aimed to determine the interobserver agreement in diagnosing DVT using
the two-point compression USG method by emergency doctors and radiologists in patients
who are thought to be likely to have DVT and need diagnostic intervention in the ED.
Patients and Methods
After the ethics committee's approval, this prospective cross-sectional study was
performed with patients who were thought to have DVT and had lower extremity venous
USG indication in a third step university hospital emergency medicine clinic between
February and July 2022. Informed consent was obtained from all patients included in
the study, and the consent of the patient or their relatives was obtained. The criteria
for inclusion in the study were over 18 years of age and the emergency doctor's indication
for lower extremity USG due to the suspicion of DVT. Patients younger than 18 years
of age, those who did not give their consent for the study or those whose data were
missing, patients whose relevant parts of both lower extremities cannot be visualized
due to bodily features such as loss of a limb loss, patients with a diagnosis of arterial
circulatory disorder known to affect the lower extremity, and those with DVT or patients
who had a recent duplex USG (within the last month) were excluded from the study.
Demographic data, admission complaints, vital signs (systolic blood pressure, diastolic
blood pressure, pulse, respiratory rate, fever, oxygen saturation value (SO2), physical examination findings, concomitant diseases, anticoagulant–antiaggregant
drug use, and two-point compression USG findings performed by emergency medicine and
radiologist of patients eligible for the study were recorded in the study form. In
addition, clinical symptoms were recorded in the study form by the Wells score in
study patients.[7] In determining the interobserver agreement between emergency medicine doctors and
radiologists, patients were evaluated by separate physicians in each application;
so, repetitive applications were not excluded from the analysis.
USG examinations were performed with Mindray Medical (Germany) device, with a 7.5 MHz
linear probe. The patients were placed in the supine position. For two-point compression
USG, compression was performed at the common femoral vein and popliteal vein points.
The common femoral vein emerges from the inguinal fold or just a few cm below it.
The probe on the transverse axis compresses it. The popliteal vein is located in the
popliteal fossa. In the popliteal vein examination, the USG device should be on the
patient's right side, and the patient should be repositioned for the study. The patient
is placed in the left lateral position, and the popliteal vein is detected in the
transverse plane in the popliteal fossa from the posterior side. The probe compresses
the remaining 3 to 4 cm in the popliteal fossa.
Data were analyzed with the MedCalc 20.110 program. Continuous data are expressed
as mean (standard deviation), and frequency data are expressed as percentages. Two-group
comparisons for frequency data were performed with the Chi-square test. Inter-rater
agreement (inter-rater agreement) was determined by the kappa value and 95% confidence
interval was used to evaluate possible DVT in the lower extremity veins by emergency
medicine doctors and radiologists using USG. All hypotheses were established in pairs,
and the α critical value was accepted as 0.05.
Results
Out of 406 patients eligible for the study, 4 were excluded because of incomplete
data and 2 did not give consent; thus, 400 patients were included in the final analysis.
The mean age of the patients was 59.8 ± 18 years. In all, 54.4% (n = 217) of the patients were male, and 45.6% (n = 183) were female. When the symptoms and physical examination findings of the patients
were evaluated, complete swelling of one lower extremity and difference in diameter
relative to the other extremity in 82.5% (n = 329) of patients, local tenderness along the deep venous system trace in 55.1%
(n = 220), 46.1% (n = 184) had pitting edema in the symptomatic leg. Moreover, 11.4% (n = 45) of the study patients were using antiaggregant drugs, and 17% (n = 27) were using anticoagulant drugs. Demographic data and clinical findings of the
patients are given in [Table 1].
Table 1
Descriptive data and co-morbidities of study patients
|
Variable Değişken
|
Ort ± SS
|
|
Age (y)
|
59.8 ± 18
|
|
Pulse
|
91 ± 17
|
|
Systolic blood pressure
|
135 ± 23
|
|
Diastolic blood pressure
|
82.6 ± 16
|
|
Oxygen saturation
|
96.2 ± 5,7
|
|
Sex
|
|
|
Male
|
217 (54.4)
|
|
Female
|
183 (45.6)
|
|
Diabetes
|
74 (18.5)
|
|
Cardiovascular disease
|
71 (17.8)
|
|
hypertension
|
58 (14.5)
|
|
Cerebrovascular condition
|
20 (5)
|
|
Entire swelling of lower extremity and difference in diameter
|
329 (82.5)
|
|
Local sensitivity along the deep venous system trace
|
220 (55.1)
|
|
Edema in symptomatic leg
|
184 (46.1)
|
|
Observation of collaterals in superficial veins (no varicose)
|
54 (13.5)
|
|
Active cancer
|
34 (8.5)
|
|
Paralysis, paresthesia, or immobilization of the lower extremity with a patch
|
27 (6.8)
|
|
Bed rest for more than 3 days or major surgery in the last 4 weeks
|
13 (3.3)
|
|
High probability of alternative diagnosis other than DVT
|
92 (23.1)
|
There was a significant difference between those with a Wells score of 2 and below
and those above 2 in DVT diagnosis (n = 67, 21.8% vs. n = 41, 47.1%; p < 0.001). There was no significant difference between patients using antiaggregant
or anticoagulants and patients not using them ([Table 2]). The findings in evaluating lower extremity veins related to DVT for DVT are given
in [Table 3]. In determining the consistency of emergency medicine, doctors and radiologists
in the evaluation of lower extremity veins for DVT, the kappa value was 0.81 (95%
CI: 0.71–0.91) for the right femoral vein, 0.89 (95% CI: 0.81–0.97) for the left femoral
vein, and the right popliteal vein. It was found to be 0.81 (95%CI: 0.72–0.91) for
the left popliteal vein, 0.73 (95% CI: 0.62–0.84) for the left popliteal vein, and
0.81 (95% CI: 0.76–0.86) for all lower extremity vein USGs ([Table 4]).
Table 2
Relationship between patients' Wells score, antiaggregant use, and anticoagulant use
with the diagnosis of DVT
|
Variable
|
DVT (−) n (%)
|
DVT (+) n (%)
|
p-Value
|
|
Wells score
|
|
|
< 0.001
|
|
≤2
|
240 (78.2)
|
67 (21.8)
|
|
>2
|
46 (52.9)
|
41 (47.1)
|
|
Antiaggregant
|
|
|
0.15
|
|
None use
|
250 (71.4)
|
100 (28.6)
|
|
Use
|
36 (81.8)
|
8 (18.2)
|
|
Anticoagulant
|
|
|
0.53
|
|
None use
|
265 (72.2)
|
102 (27.8)
|
|
Use
|
21 (77,8)
|
6 (22.2)
|
Abbreviations: DVT: deep vein thrombosis.
Table 3
Two-point compression ultrasound interobserver consistency in terms of DVT by emergency
medicine and radiology physicians
|
Emergency doctor
|
Radiologist
|
|
|
Right femoral vein
|
+
|
–
|
Total
|
|
ED (+)
|
32 (82)
|
7 (18)
|
39
|
|
ED (−)
|
5 (2,5)
|
196 (97,5)
|
201
|
|
Left femoral vein
|
|
|
|
|
ED (+)
|
37 (90,2)
|
4 (9,8)
|
41
|
|
ED (−)
|
3 (2,1)
|
140 (97,9)
|
143
|
|
Right popliteal vein
|
|
|
|
|
ED (+)
|
39 (84,8)
|
7 (15,2)
|
46
|
|
ED (−)
|
7 (3,6)
|
187 (96,4)
|
194
|
|
Left popliteal vein
|
|
|
|
|
ED (+)
|
41 (87,2)
|
6 (12,8)
|
47
|
|
ED (−)
|
14 (10,2)
|
123 (89,8)
|
137
|
|
All lower extremity Veins
|
|
|
|
|
ED (+)
|
149 (86,1)
|
24 (13,9)
|
173
|
|
ED (−)
|
29 (4,3)
|
645 (95,7)
|
674
|
Abbreviation: ED, emergency doctor.
Table 4
Kappa values in determining the interobserver consistency of emergency medicine doctor
and radiologist in the evaluation of lower extremity veins for DVT
|
Evaluated vein
|
Kappa value (%95 Cl)
|
|
Right femoral vein
|
0.81 (0.71–0.91)
|
|
Left femoral vein
|
0.89 (0.81–0.97)
|
|
Right popliteal vein
|
0.81 (0.72–0.91)
|
|
Left popliteal vein
|
0.73 (0.62–0.84)
|
|
All lower extremity veins
|
0.81 (0.76–0.86)
|
Abbreviation: CI, confidence interval.
Discussion
The mean age of the patients participating in the study was 59.8 years. In the study
by Kim et al,[8] the mean age of the patients was calculated as over 50 years. Olaf et al[1] also reported that the incidence of DVT increases with age. The results of our study
are compatible with the literature. Long-term immobilization and previous major surgery
are risk factors in DVT risk scoring.[9] It was found that 13 patients in our study had bed rest for more than 3 days or
had a history of major surgery in the last 4 weeks. In the 2018 DVT guideline, it
was stated that previous surgery and immobilization cause an increase in the risk
of DVT.[10] In line with our study's results, prophylactic anticoagulants in prophylactic doses
should not be neglected in patients who are planned for long-term immobilization and
major surgery.
The most common clinical finding in patients for whom USG is requested with the suspicion
of DVT in the emergency department is complete swelling of the lower extremity and
the difference in diameter compared with the other extremity (82.5%). Local tenderness
(55.1%) along the deep venous system trace, symptomatic pitting edema (46.1%), and
non-varicose collaterals in the superficial veins (13.5%) are other findings following
lower extremity swelling and diameter difference. Liang et al[11] in their DVT study published in 2022 found swelling in the extremity, detection
of diameter difference with the other lower extremity, and tenderness along the venous
system tracing as the most common physical examination findings in patients diagnosed
with DVT. Wells score is one of the best-known and most commonly used scoring systems
in diagnosing DVT and pulmonary embolism.[12]
[13] According to the results of this study, the incidence of DVT in patients with a
Wells score of 2 and below (low probability) was significantly lower than in those
with a Wells score above two (21.8% vs. 47.1%). It is an expected result that the
likelihood of DVT decreases as the Wells score drops, and it is compatible with previous
studies on this subject.
The first imaging method to diagnose DVT is lower extremity venous Doppler USG. For
the diagnosis of DVT, 2-point compression USG at the bedside has been performed by
emergency medicine physicians in the emergency departments for diagnostic purposes
in recent years.[14] In USG performed for the diagnosis of DVT in all lower extremity vessels, emergency
medicine physicians reported DVT in 173 patients, while radiologists found DVT in
178 patients. In a study conducted by Kim et al[8] with 296 patients, an emergency medicine physician and a radiologist diagnosed DVT
in 50 patients. In five patients, the emergency medicine physician said there was
no DVT, while the radiologist diagnosed DVT.[8] In a study by Crisp et al,[15] in which emergency physicians and radiologists compared the USG skills for DVT diagnosis,
the radiologist stated that only 1 of the 153 patients whom emergency medicine physicians
called negative for DVT had positive USG findings. Canty et al[16] found that the sensitivity of compression USG for DVT was 95% (87–99%) and the specificity
96% (87–99%) by emergency physicians in the ED. In our study, 149 (86%) of 173 patients
diagnosed with DVT by ED physicians in the whole lower extremity vein ultrasound were
also agreed by radiologists. In a study by Abbasi et al,[17] the kappa value was calculated to be in a significant range (0.9) in the consistency
comparison of the compression USG made by the ED physician and the radiologist for
the diagnosis of DVT. In our study, in the comparison of the consistency of emergency
medicine physicians and radiology physicians in the evaluation of lower extremity
veins for DVT, the kappa value for the right femoral vein was in a significant range
(0.81), and the kappa value for the left femoral vein (0.89). When examined for all
lower extremity veins, the kappa value was calculated as 0.81, which was found to
be very compatible.
The results found in our study, which were observed to be compatible with the literature,
were found to be sensitive to two-point compression USG performed by emergency medicine
physicians for DVT USG.
This study had some limitations. The USG indication of study patients was left to
the clinical judgment of the physician rather than a standard set of criteria. Although
this reduces internal validation and increases the likelihood of variation in results,
it is a pragmatic approach more suited to daily practice. This limitation should always
be considered, as the USG is user-dependent due to the study's methodology. In contrast,
the diameter difference between the legs of the study patients could not be measured
using a standard method with an instrument measuring distance and length. Instead,
it is left to the clinician's decision as to whether there is a difference in diameter.
The existing but faint diameter differences may have been overlooked in this case.
Conclusion
The most common clinical finding in patients with suspected DVT in the ED is complete
swelling of the lower extremity and diameter difference. The incidence of DVT is higher
in patients with intermediate and high probability, according to the Wells score.
There is good interobserver agreement among emergency medicine and radiologists in
diagnosing DVT by USG.
