Tutorial #26: DVT Flashcards
What is the modified Wells score for DVT (x10 items)
- Paralysis/recent immobiization = 1
- Active cancer or cancer treated within six months = 1
- Recently bedridden for longer than 3 days or major surgery within the past four weeks = 1
- Localized tenderness in the deep vein system = 1
- Swelling of the entire leg = 1
- Calf swelling > 3cm more than other leg =1
- pitting edema greater confined to symptomatic leg = 1
- collateral nonvaricose superficial veins = 1
- previously documented DVT = 1
- Alternative diagnosis more likely than DVT = -2
In the 3-level Wells for DVT, what is the pretest probabily for “low probability of DVT” (-2 to 0). What is the best investigation to pursue at this time?
5%, can rule out with negative D-dimer
In the 3-level Wells for DVT, what is the pretest probabily for “moderate probability of DVT” (1-2). What is the best investigation to pursue at this time?
17%, can rule out with negative D-dimer
In the 3-level Wells for DVT, what is the pretest probabily for “high probability of DVT” (3-8). Can you use a D-dimer test?
53%, no role for D-dimer as rule out test
List TWO patient populations where D-dimer is not used for rule out of DVT, and list why.
- Inpatients: has been studied and shown that negative d-dimer with appropriate Wells Score DOES NOT rule out DVT.
- Pregnant patients: this patient population that NOT been included in previous studies, and effectiveness of d-dimer is largely unknown*.
Notably, d-dimer PE CAN be used with YEARS criteria in pregnant patients, as shown in several trials. So far, no strong literature for rule out of DVT though.
What is the diagnostic imaging choice for DVT?
ultrasound
Venography is considered the gold standard test for DVTs, however it is rarely, if ever, performed anymore.
What is the usual treatment of DVT?
anti-coagulation
*Choices include heparin, LMWH, DOAC, wafarin.
*if it is the patients first VTE and it was precipitated by something, then theyre usually treated for 3-6 months AND until resolution of the precipitant. Otherwise patients are considered for indefinite treatment based on their individual risks for VTE which are weighed against their risk of bleeding.
For a DVT, if ultrasound testing is negative, and the pre-test probability was low-moderate, what is the next best course of action?
DVT is ruled out
For a DVT, if ultrasound testing is negative, and the pre-test probability was high, what is the next best course of action?
Repeating ultrasound in 1 week
In clinical medicine, define the term “Miss rate”
The miss rate refers to the number of patients in whom we miss a particular diagnosis. In general, clinicians would like a low miss rate, but aiming for a zero miss rate leads to unnecesary testing.
The risk factors for DVT include Virchows Triad, which is?
- (venous) stasis
- endothelial injury
- hypercoagubility
- Venous stasis -> recent immobilization/flight, casting, recent surgery or hospitalization.
- Venous catheter placement, trauma
- hypercoagubility -> malignancy, hormone replacement, IBD, pregnancy, family history of VTE.
What are three positive predictors of DVT?
unilateral leg swelling, pain, and leg warmth.
What is cellulitis? How can you differentiate on inspection from DVT?
it is a bacterial skin infection
Erythema, patch form and localized distribution.
- DVT does not localize in the same way as cellulitis
What are the 3 positive predictors of cellulitis
- Uniformly tender patch with associated erythema/warmth.
- Fever
- Pain/swelling distributed in contiguous area of soft tissue
How can you differentiate chronic venous insufficiency from DVT?
Usually presents as bilateral and chronic swelling (*but chronic venous insuficiency can be unilateral as well)
what are three positive predictors for chronic venous insufficiency?
- bilateral swelling
- skin discolouration
- stasis ulcers
