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Latest revision as of 03:32, 20 May 2014



Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Vidit Bhargava, M.B.B.S [2]; Rim Halaby, M.D. [3]

Overview

Deep vein thrombosis (DVT) is the formation of a blood clot ("thrombus") in a deep vein.

Causes

Life Threatening Causes

Deep venous thrombosis can be a life-threatening condition if thromboembolism and subsequent pulmonary embolism occur, and it must be treated as such irrespective of the underlying cause.

Common Causes

FIRE: Focused Initial Rapid Evaluation

A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.

Complete Diagnostic Approach for First Episode of DVT

Shown below are the different diagnostic approaches to the diagnosis of DVT depending on the pre-test probability of the disease.[1]

Low Pretest Probability

 
 
 
 
 
 
 
 
 
 
 
 
 
 
The patient has a low pre-test probability for DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with one of the following:
Highly or moderately sensitive D-dimer test (1st line)
Proximal US (2nd line)
Whole leg US (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
D-dimer (1st line)
 
 
 
 
 
 
 
 
 
 
Proximal US (2nd line)
 
 
 
 
 
 
Whole leg US (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
 
 
 
 
Positive
 
 
 
 
Negative
 
Positive
 
Negative
 
 
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with either:
Proximal US (1st line)
OR
Whole leg US (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
What is the location of the DVT?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Proximal US (1st line)
 
 
 
 
Whole leg US (less preferred)
 
DVT is excluded
 
Treat DVT
 
DVT is excluded
 
Proximal DVT
 
Isolated distal DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
Treat DVT
 
Perform serial US (1st line)
OR
Treat DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
What is the location of the DVT?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Treat DVT
 
DVT is excluded
 
Proximal DVT
 
Isolated distal DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Treat DVT
 
Perform serial US (1st line)
OR
Treat DVT
 
 
 
 
 
 
 
 
 
 
 

Moderate Pretest Probability

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The patient has a moderate pre-test probability of DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with one of the following:

D-dimer test
Proximal US

Whole leg US
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Highly sensitive D-dimer test
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proximal US
 
 
 
 
 
Whole leg US
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
 
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
 
 
 
Positive
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with either:
Proximal US
OR
Whole leg US
 
 
 
 
 
 
 
 
 
 
 
 
Repeat proximal US
OR
Moderately/highly sensitive D-dimer
 
 
 
 
Treat DVT
 
DVT is excluded
 
Where is the location of the DVT?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Proximal US
 
 
 
Whole leg US
 
 
 
 
 
Repeat proximal US within 1 week
 
 
 
Moderately/highly sensitive D-dimer
 
 
 
 
 
 
 
Proximal DVT
 
Isolated distal DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
Negative
 
Positive
 
Negative
 
Positive
 
Negative
 
Positive
 
 
 
Treat DVT
 
Perform serial US (1st line)
OR
Treat DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Repeat proximal US within 1 week
 
Treat DVT
 
DVT is excluded
 
What is the location of the DVT?
 
DVT is excluded
 
Treat DVT
 
DVT is excluded
 
Repeat proximal US within 1 week
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
 
 
Proximal DVT
 
Isolated distal DVT
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Treat DVT
 
 
 
Treat DVT
 
Perform serial US (1st line)
OR
Treat DVT
 
 
 
 
 
 
 
 
 
Treat DVT
 
Perform serial US (1st line)
OR
Treat DVT

High Pretest Probability

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The patient has a high pre-test probability for DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with either:
Proximal US
OR
Whole leg US
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proximal US
 
 
 
 
 
Whole leg US
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with ONE of the following:
Repeat proximal US
Highly sensitive D-dimer
Whole leg US
Venography (less preferred)
 
Treat DVT
 
DVT is excluded
 
What is the location of the DVT?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proximal
 
Distal
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Treat DVT
 
Perform serial US (1st line)
OR
Treat DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Repeat proximal US within 1 week
 
 
 
 
 
Highly sensitive D-dimer
 
 
 
 
 
Whole leg US
 
 
 
 
 
 
Venography
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
Negative
 
Positive
 
Negative
 
 
Positive
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Treat DVT
 
DVT is excluded
 
 
 
 
 
 
DVT is excluded
 
 
Where is the location of the DVT?
 
DVT is excluded
 
Treat DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Repeat proximal US within 1 week
 
 
 
 
 
Whole leg US
 
 
 
 
 
Venography (less preferred)
 
 
 
Proximal
 
Distal
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
Negative
 
Positive
 
Negative
 
Positive
 
Treat DVT
 
Perform serial US (1st line)
OR
Treat DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Treat DVT
 
DVT is excluded
 
Where is the location of the DVT?
 
DVT is excluded
 
Treat DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proximal
 
Distal
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Treat DVT
 
Perform serial US (1st line)
OR
Treat DVT
 
 

Complete Diagnostic Approach for Recurrent DVT

Shown below is the diagnostic approach to suspected recurrent DVT. The recommended initial test is either proximal ultrasound (US) or highly sensitive D-dimer tetsing rather than venography, CT venography or MR imagining. Initial D-dimer testing is recommended over proximal US in case there is no prior ultrasound for comparison. Note the following definitions:

  • Negative US:
    • Normal US, or
    • Increase in residual diameter of less than 2 mman, or
    • Area of prior noncompressibility with a decreased or stable residual diameter
  • Nondiagnostic US:
    • Ultrasound that is technically limited, or
    • Area of prior noncompressibility with an increment in residual venous diameter of < 4 mm yet ≥ 2 mm, or
    • Area of prior noncompressibility in the absence of a previous measurement of the residual diameter
  • Positive US:
    • New noncompressible segment, or
    • Area of prior noncompressibility with an increment in residual venous diameter of ≥ 4 mm
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The patient has recurrent DVT
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with one of the following:
Proximal US
Moderately/highly sensitive D-dimer
Venography (less preferred)
CT venography (less preferred)
MR imaging (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proximal US
 
 
 
 
 
 
 
 
 
Moderately/highly sensitive D-dimer
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Non diagnostic
 
Positive
 
 
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with one of the following:
D-dimer
Repeat proximal US within 1 week
Venography (less preferred)
No further testing (less preferred)
 
Click here for the diagnostic approach in case of inconclusive US
 
Treat
OR
Venography (less preferred)
 
 
 
DVT is excluded
 
Proximal US
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Moderately/highly sensitive D-dimer
 
 
 
 
 
Repeat US
 
 
 
 
 
Venography
 
No further testing
 
Negative
 
Non diagnostic
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
Negative
 
Positive
 
Negative
 
Positive
 
 
 
Repeat proximal US within 1 week
OR
Venography (less preferred)
OR
No further testing (less preferred)
 
Click here for the diagnostic approach in case of inconclusive US
 
Treat
OR
Venography (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Repeat proximal US within 1 week
OR
Venography (less preferred)
OR
No further testing (less preferred)
 
DVT is excluded
 
Treat
OR
Venography (less preferred)
 
DVT is excluded
 
Treat DVT
 
 
 
If proximal US is repeated, what is the result?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
If proximal US is repeated, what is the result?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Treat
OR
Venography (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Treat
OR
Venography (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Diagnostic Approach for Non Diagnostic Ultrasound

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The patient has a non diagnostic proximal US
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Are prior US results available?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Yes
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
No
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with ONE of the following:
Venography (most preferred)
Repeat proximal US within 1 week
Highly/moderately sensitive D-dimer
Treat DVT (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proceed with ONE of the following:
Venography (most preferred)
Highly sensitive D-dimer
Repeat proximal US (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Venography (most preferred)
 
 
 
 
 
Repeat proximal US within 1 week
 
 
 
 
 
Highly/moderately sensitive D-dimer
 
Treat DVT (less preferred)
 
Venography (most preferred)
 
 
 
 
 
Highly sensitive D-dimer
 
Repeat proximal US within 1 week
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
Negative
 
Positive
 
Negative
 
Positive
 
Negative
 
Positive
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Treat DVT
 
DVT is excluded
 
Treat DVT
OR
Venography (less preferred)
 
DVT is excluded
 
Repeat proximal US within 1 week
 
DVT is excluded
 
Treat DVT
 
DVT is excluded
 
Venography
OR
Treat DVT (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Venography (less preferred)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Diagnostic Approach for Venography

 
 
What is the result of the venography?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Negative
 
Positive
 
 
 
 
 
 
 
 
 
 
 
 
DVT is excluded
 
Treat DVT
 

Long Term Treatment

Shown below is the long term treatment for DVT. Note that not all patients with isolated distal DVT are started on anticoagulation, only those who are started require long term therapy with anticoagulation. Patients who are planned to receive long term therapy with anticoagulation should be assessed regularly for the risks vs benefits of anticoagulation therapy.[2]

 
 
 
 
 
 
 
Is the DVT provoked or unprovoked?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Provoked
 
 
 
 
 
 
 
Unprovoked
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
What is the predisposing factor?
 
 
 
 
 
 
 
Is this the first or second episode?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Surgical
OR <bt>Transient non surgical predisposing factor
 
Cancer
 
First episode
 
 
 
 
 
Second episode
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Anticoagulation therapy for 3 months
 
Extended anticoagulation therapy
 
Is the DVT proximal or distal?
 
 
 
 
 
What is the risk of bleeding?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Proximal DVT
 
Isolated distal DVT
 
Low or moderate risk of bleeding
 
High risk of bleeding
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
What is the risk of bleeding?
 
Anticoagulation therapy for 3 months
(irrespective of the risk of bleeding)
 
Extended anticoagulation therapy
 
Anticoagulation therapy for 3 months
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Low or moderate
 
High
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Extended anticoagulation therapy
 
Anticoagulation therapy for 3 months
 
 
 
 
 
 

Assessment of Risk of Bleeding

The risk factors of bleeding with anticoagulation therapy are:[3]

Shown below is a table summarizing the risk of bleed based on the number of risk factors. Note that, although the presence of one risk factor signify moderate risk of bleeding, if the single risk factor is severe (such as severe thrombocytopenia or recent major surgery) then the patient is at high risk of bleeding despite the presence of a single risk factor.

Risk of bleeding Number of risk factors[3]
Low Risk 0
Moderate Risk 1
High Risk ≥2

Do's

  • Among patients with low pretest probability of DVT, the preferred initial test is D-dimer. However, among those patients who have comorbidities known to increase D-dimer concentration in the absence of a venous thromboembolism, ultrasound is preferred as an initial test.
  • Patients with low pretest probability of DVT among whom an ultrasound can not be practically performed, for example due to the presence of a leg cast, or those who have non-diagnostic ultrasound results, CT scan venography, magnetic resonance venography, or magnetic resonance direct thrombus imaging can be considered instead of venography.
  • Among patients with moderate pretest probability of DVT, whole leg US might be preferred over proximal US in case there is severe symptoms consistent with calf pain or in case the patients have difficulty returning for the serial US tests. Patients among whom an ultrasound can not be practically performed, for example due to the presence of a leg cast, or those who have non-diagnostic ultrasound results, CT scan venography, magnetic resonance venography, or magnetic resonance direct thrombus imaging can be considered instead of venography.
  • Among patients who underwent whole leg ultrasound that revealed isolated distal DVT, consider serial US testing over trearment to check for extension of the thrombus. However, if the pretest probability is high or there is elevated risk of extension or severe symptoms, consider treatment over serial US testing.

Don'ts

References

  1. Bates SM, Jaeschke R, Stevens SM, Goodacre S, Wells PS, Stevenson MD; et al. (2012). "Diagnosis of DVT: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines". Chest. 141 (2 Suppl): e351S–418S. doi:10.1378/chest.11-2299. PMC 3278048. PMID 22315267.
  2. Guyatt GH, Akl EA, Crowther M, Gutterman DD, Schuünemann HJ, American College of Chest Physicians Antithrombotic Therapy and Prevention of Thrombosis Panel (2012). "Executive summary: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines". Chest. 141 (2 Suppl): 7S–47S. doi:10.1378/chest.1412S3. PMC 3278060. PMID 22315257.
  3. 3.0 3.1 Kearon C, Akl EA, Comerota AJ, Prandoni P, Bounameaux H, Goldhaber SZ; et al. (2012). "Antithrombotic therapy for VTE disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines". Chest. 141 (2 Suppl): e419S–94S. doi:10.1378/chest.11-2301. PMC 3278049. PMID 22315268.

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