Wells Prediction Rule
Venous Ultrasound
Update
Laurence Needleman, MD
Sidney Kimmel Medical College
Thomas Jefferson University
Philadelphia, PA
for Predicting Pretest Probability
Active cancer (active, within previous 6m, palliative)
1
Paralysis, paresis or recent plaster immobilization
1
Recently bedridden more than 3 days or major surgery within
12 weeks requiring Gen or Reg Anest
1
Localized tenderness along the distribution of the deep veins
1
Entire leg swollen
1
Calf swelling 3 cm larger than asymptomatic side (measured 10 1
cm below tibial tuberosity)
Pitting edema confined to the symptomatic leg
1
Collateral superficial veins (not varicose)
1
Alternative diagnosis at least as likely as DVT
-2
Risk category: low risk ≤0 points; intermediate risk=1 or 2 points; high risk ≥3 points.
Safe Strategies
Current Diagnosis of Venous Thromboembolism in Primary Care: A Clinical
Practice Guideline from the American
Academy of Family Physicians and the
American College of Physicians
Amir Qaseem, MD, PhD, MHA1
Vincenza Snow, MD, MS1
Patricia Barry, MD, MPH2
E. Rodney Hornbake, MD3
Jonathan E. Rodnick, MD4
Timothy Tobolic, MD5
Belinda Ireland, MD, MS6
Jodi Segal, MD7
Eric Bass, MD, MPH7
Kevin B. Weiss, MD, MPH8
Lee Green, MD, MPH9
Douglas K. Owens, MD, MS10
the Joint American Academy
of Family Physicians/American
College of Physicians Panel on
Deep Venous Thrombosis/
Pulmonary Embolism
Annals Journal Club selection;
see inside back cover or http://www.
annfammed.org/AJC/.
ABSTRACT
This guideline summarizes the current approaches for the diagnosis of venous
thromboembolism. The importance of early diagnosis to prevent mortality and
morbidity associated with venous thromboembolism cannot be overstressed. This
field is highly dynamic, however, and new evidence is emerging periodically that
may change the recommendations. The purpose of this guideline is to present
recommendations based on current evidence to clinicians to aid in the diagnosis
of lower extremity deep venous thrombosis and pulmonary embolism.
Ann Fam Med 2007;5:57-62. DOI: 10.1370/afm.667.
RECOMMENDATIONS
Recommendation 2
In appropriately selected patients with low pretest probability of DVT or pulmonary
embolism, obtaining a high-sensitivity D-dimer is a reasonable option, and if negative,
American College of Physicians,
Philadelphia, Penn
Merck Institute of Aging and Health,
Gloucester Point, Va
3
Private practice, Hadlyme, Conn
4
University of California, San Francisco,
San Francisco, Calif
5
Byron Family Medicine, Byron Center,
Miss; American Academy of Family
Physicians, Leawood, Kan
6
BJC HealthCare, St. Louis, Mo; American
Academy of Family Physicians, Leawood, Kan
7
Johns Hopkins University School of
Medicine, Baltimore, Md
8
Hines Veterans Affairs Hospital and
Northwestern University, Chicago, Ill
9
University of Michigan, Ann Arbor, Mich
10
Veterans Affairs Palo Alto Health Care
System and Stanford University, Stanford,
Calif
1
•  Normal
CORRESPONDING AUTHOR
Amir Qaseem, MD, PhD, MHA
American College of Physicians
190 N Independence Mall West
Philadelphia, PA 19106
aqaseem@acponline.org
–  1-1.5% in 6 month
•  Safe strategies
–  Low pretest probability and negative DD
–  Low pretest probability and negative US
–  Negative whole leg ultrasound only
Pretest Probability
D-Dimer
3-month incidence of DVT
(%)
0.5
Low
Negative
Intermediate
Negative
3.5
High
Negative
21.4
Recommendation 1
Validated clinical prediction rules should be used to estimate pretest probability of venous
thromboembolism (VTE), both deep venous thrombosis (DVT) and pulmonary embolism, and for the basis of interpretation of subsequent tests.
Good quality evidence supports the use of clinical prediction rules
to establish pretest probability of disease. The Wells prediction rules for
DVT and for pulmonary embolism (Tables 1 and 2) have been validated
and are frequently used to estimate the probability of VTE before performing more definitive testing on patients. The Wells prediction rule
performs better in younger patients without comorbidities or a history
of VTE than it does in other patients. Physicians should use their clinical
judgment in cases where a patient is older or presents with comorbidities.
Doppler Findings in LE Veins
Conflicts of interest: none reported
•  Risk of DVT equal or less than normal venogram
2
Spectral Doppler - Normal
–  Phasic variation
•  Velocity changes which alter with
respiration
ANNALS OF FAMILY MEDICINE
✦
WWW.ANNFAMMED.ORG
✦
VOL. 5, NO. 1
✦
JANUARY/FEBRUARY 2007
57
•  Abnormal
–  Continuous Doppler signal
•  Proximal intrinsic or extrinsic obstruction
•  Collaterals from prior DVT
–  Absent signal
1
Spectral Doppler - Abnormal
•  Continuous Venous Signal
–  Venous Obstruction
•  DVT
•  Extrinsic Obstruction
Noncompressible Vein: Causes
•  Acute venous thrombosis
•  Scarring
•  Inadequate compression
–  Prior Thrombosis
•  Collaterals
•  Pulsatile Spectral Doppler
–  Elevated right heart pressure
–  Tricuspid regurgitation
Without compression
With compression
Acute Deep Venous Thrombus
Acute Venous Thrombosis
•  Soft, deformable
with compression
•  Enlarges vein
•  Smooth
•  Free floating
Residual Venous Thrombosis
(aka Scar or Chronic Venous Change)
Great saphenous vein
•
•
•
•
Femoral vein
•  Web (synechia)
•  Vein small or normal
Stiff (non-deformable)
Irregular
Incorporated into wall
Wall thickening
–  Sometimes circumferential
CFV
Residual Venous Thrombosis
Extent of Compression
Thigh to knee
AIUM/ACR
IAC-VT
(ICAVL)
√
√
Calf to ankle
Symptomatic areas if symptoms
not elucidated by proximal scans
√
Selective calf to
ankle US
May need calf if calf
pain and no other
areas of DVT
√
AIUM= American Institute of Ultrasound in Medicine
ACR= American College of Radiology
ICAVL=Intersocietal Accreditation Commission – Vascular Testing
2
Origin of Venous Thrombosis
“Thrombi in calf veins are often found to be
independent of thrombi in thigh veins... The…
evidence... points to the deep veins of the calves as
the site of origin of thrombi in the great majority of
patients without local trauma; at a later stage in the
disease, independent thrombi may form elsewhere
in the lower limbs”.
Thomas DP, Sem Thromb Hemost, 14:1, 1988
Calf DVT is present in 83% of
symptomatic patients (Venograms)
•  2762 Venograms
•  Calf involvement 83%
–  Femoropop 53%
–  Iliac 9%
•  Isolated calf vein DVTs
34.7%
•  Isolated DVT without calf
only 17%
J Vasc Surg 2000;31:895-900
Calf DVT Controversy: Con
Calf imaging not necessary
•  Calf DVT rarely causes pulmonary embolism
•  Treatment is controversial (so need to image
calf is also controversial)
•  Calf DVT self limited in 80%
•  If thigh to knee US negative, followup US at 1
week, rather than calf ultrasound,
recommended by some organizations in
moderate and high risk groups
Calf DVT Controversy: Pro
Calf DVT has important consequences
Good to scan calf
20%
Recurrent DVT
•  Acute DVT after prior DVT (up to ¼)
•  Extremely difficult diagnosis
•  Best sign
Initial -8mm
+7 mos – 4mm
–  New DVT away from site of prior DVT
•  “Enlargement” of clot compared with
earlier scan
•  Acute appearing DVT on area of scar
–  Free floating, soft and deformable
–  Scarred vein may not allow dilatation but
enlarged vein helpful if present
+11 mos – 4mm
+13 mos – 9mm
Popliteal vein
recurrent thrombosis
+45 mos – 4mm
3
Recurrent DVT Acute on scar Stopping Anticoagulation
•  Rationale: keep anticoagulation longer
if recurrence risk is still high
– Based on length of Rx
– Based on risk factors (hypercoagulable)
– Based on d-dimer
– Based on US for residual venous
thrombosis
– Based on risk of continuing
anticoagulation
Is one negative US enough?
What we don t know
•  How accurate is venous US in the setting of
prior DVT?
–  Almost all research studies performed with patients
at first presentation of DVT (prior DVT is an
exclusion)
•  Does a normal study mean the same thing in a
pregnant woman?
•  and more
What to do with uncertainty
Rules for follow up
•  Who – Positive for calf DVT •  How – “A follow up in 5 to 7 days is recommended to exclude progression if the patient is not treated” – If no change at one week, repeat – If change, treat What to do with uncertainty
Rules for follow up
•  Who
–
–
–
–
–
–
Negative DVT with inadequate or NO calf
Negative DVT with prior history of DVT
Negative DVT during pregnancy
Negative DVT with quality issues
+/- Negative DVT from ER
+/- Negative DVT with scar (residual venous thrombosis)
•  How
– “If there is continuing or high concern for
acute DVT, consider follow up in 5 to 7 days”
Gray scale differentiation of
Acute Thrombus from Scarring
Acute Venous Thrombosis
Scarring (aka Residual venous
thrombosis, chronic change)
• Noncompressible but deformable
• Smooth margin
• Free floating (loosely attached to
wall)
• Enlarged
• Noncompressible, nondeformable
• Irregular margin
• Incorporated into vein wall
• Normal or small vein
• Circumferential wall thickening
• Irregular lumen
• Web(s)
Not helpful: Echogenicity, collaterals
4