Clinical approach to the diagnosis of deep vein
thrombosis
Summary of DVT risk assessment (THRIFT: BMJ 1992;
305:567-74)
| HIGH RISK |
MODERATE RISK |
LOW RISK |
- Fracture or major orthopaedic surgery (> 30 minutes) of
pelvis, hip or lower limb (including amputation)
- Major pelvic or abdominal surgery for cancer
- Major surgery, trauma or illness in patients with:
- Previous deep vein thrombosis
- Previous pulmonary embolism
- Thrombophilia (deficiency of antithrombin, protein C or
protein S; lupus anticoagulant)
- Acute lower limb paralysis (e.g. hemiplegic stroke
paraplegia)
|
- Major general, urological, gynaecological, cardiothoracic,
vascular or neurological surgery and any of the following: Age
over 40 years Obesity Varicose Veins Malignancy Infection Heart
failure or recent myocardial infarction Paralysis of lower limbs
Inflammatory bowel disease or nephrotic syndrome Polycythaemia,
paraproteinaemia, paroxysmal nocturnal haemoglobinaemia,
Behcet's syndrome or homocystinaemia
- Major trauma (other than pelvis/lower limb) or burns
- Major immobilising medical illness e.g. heart or lung
disease, cancer, inflammatory bowel disease, septicaemia
- Minor surgery, trauma or illness in patients with previous
deep venous thrombosis, pulmonary embolism or thrombophilia
|
- Minor surgery < 30 mins. Any age. No other risk factors.
- Major surgery > 30 mins. Age < 40. No other risk factors.
- Minor trauma or medical illness.
|
Incidence of Thromboembolism According to Risk Groups
| |
RISK |
| DVT |
FATAL PE |
| LOW |
<10% |
0.01% |
| MOD |
10 - 40% |
0.1 - 1% |
| HIGH |
40 - 80% |
1 - 10% |
Risk Groups
| LOW |
- Minor surgery <30 minutes. Any age. No risk factors.
- Major surgery >30 minutes. Age <40. No other risk factors.
- Minor trauma or medical illness.
|
| MODERATE |
- Major surgery. Age ?40 or other risk factors.
- Major medical illness: heart/lung disease, CA, inflammatory
bowel disease.
- Major trauma/burns.
- Minor surgery, trauma, medical illness in pt with previous DVT,
PE or thrombophilia.
|
| HIGH |
- Major orthopaedic surgery or # pelvis, hip, lower limb.
- Major abdo/pelvic surgery for ca.
- Major surgery, trauma, medical illness in pt with DVT, PE or
thrombophilia.
- Lower limb paralysis (e.g. stroke, paraplegia).
- Major lower limb amputation
|
Risk Factors for Thromboembolism
| Patient |
Disease |
- Age
- Obesity
- Immobility
- Pregnancy/puerperium
- High dose oestrogen therapy
- Prev. DVT/PE
- Thrombophilia
|
- Trauma or surgery, esp. pelvis, hip, lower limb.
- Malignancy, esp. pelvic, abdominal metastatic.
- Heart Failure
- Recent M I
- Lower limb paralysis
- Infection
- Inflammatory bowel disease
- Nephrotic syndrome
- Polycythaemia
- Paraproteinaemia
- Paroxysmal nocturnal haemoglobinuria
- Behcet's disease
- Homocystinaemia
|
GUIDELINES FOR DVT PROPHYLAXIS ACCORDING TO RISK CATEGORY GUIDELINE
RECOMMENDATIONS FOR DVT PROPHYLAXIS
The following are guidelines for prophylaxis for each of the risk categories.
Certain patients will need to be excluded from these recommendations, for
example patients with a history of recent bleeding. It is emphasised that these
are guidelines only. The final decision regarding the use and nature of
prophylaxis lies with the individual consultant. Changes in clinical practice
may lead to previously high risk procedures becoming moderate or low risk.
The required duration or extended use of prophylaxis remains unclear and
there is some evidence that prophylaxis may need to be continued in some
patients after discharge. Further studies are required to address this issue
(see THRiFT II)1 and individual clinical judgement should be used.
| High Risk |
- Graduated elastic anti embolism stockings (e.g. Kendal T.E.D.)
plus
- Unfractionated Heparin 5000 Units s/c b.d. or t.d.s. (there is
evidence that Heparin given 8 hourly may be more effective than 12
hourly). Start on admission or greater than 2 hours before surgery
or
Low molecular weight Heparin (contact hospital pharmacy for
available products and dose)
or
Adjusted dose Warfarin (INR 2-3)
- Consider intermittent pneumatic compression
|
| Moderate Risk |
- Graduated elastic anti embolism stockings (e.g. Kendal T.E.D.)
and/or
- Low dose unfractionated Heparin. - 5000 Units s/c b.d. or t.d.s.
- Start on admission or greater than 2 hours before surgery (there
is evidence that Heparin given 8 hourly may be more effective than
12 hourly)
or
Low molecular weight Heparin (contact hospital pharmacy for
available products and dose)
|
| Low Risk |
- Early mobilisation
|
SPECIFIC EXAMPLES OF ANTITHROMBOTIC PROPHYLAXIS IN CLINICAL SITUATIONS
SPECIFIC ANTI THROMBOTIC PROPHYLAXIS
| MEDICAL CONDITIONS |
High Risk |
- Acute stroke with paralysis of lower limb
Although low dose Heparin reduces deep venous thrombosis and
pulmonary emboli, recent trials have shown that this is matched by
an increase in haemorrhagic transformation of an ischaemic stroke.
Therefore, although there may be specific patients in whom low dose
Heparin might be considered for prophylaxis, the vast majority of
patients should be treated using anti embolism stockings, followed
by early mobilisation. Therefore, these patients do not fall into
the general guideline recommendations.
|
| |
Moderate Risk |
- Patients immobilised with major acute medical
illness e.g. heart failure, chest infection, malignancy,
inflammatory bowel disease, diabetic acidosis or hyperosmolarity
Subcutaneous standard low dose Heparin 5000 Units b.d. (or low
molecular weight Heparin) + graduated elastic compression stockings.
If Heparin contra indicated, intermittent pneumatic compression.
- Acute myocardial infarction
Many of these patients will receive Aspirin, thrombolytic drugs and
full anti coagulation. In other patients not receiving these,
prophylaxis of venous thromboembolism, should be considered
according to risk assessment group e.g. in (a) above.
|
| WOMEN TAKING ORAL CONTRACEPTIVES OR HORMONE REPLACEMENT
THERAPY |
|
- Progesterone only contraceptive pill
There is no need to stop these preparations prior to elective
surgery. Patients should have a risk assessment profile performed as
with any patient.
- The combined oral contraceptive pill & hormone
replacement therapy
This area remains controversial and is a balance of a small absolute
excess risk in users against the risks of stopping the pill 4-6
weeks prior to surgery which include unwanted pregnancy, the effects
of surgery and anaesthesia on the pregnancy and the risks of
subsequent termination. The combined OCP need not be ceased nor
thromboprophylaxis instituted in women undergoing uncomplicated
minor and intermediate procedures. For moderate risk patients the
risks should be discussed with the patient and consideration whether
or not to stop the pill and whether to use anti thrombotic
prophylaxis should be judged in each case according to additional
risk factors and to contraceptive difficulties. In emergency surgery
routine prophylaxis should be given as thromboembolism risk is
greater. Recent evidence suggests that there is a slightly higher
risk of thrombosis in patients on hormone replacement therapy and
therefore consideration should be given to either stopping this
prior to surgery or using anti thrombotic prophylaxis.
|
| PREGNANCY & THE PUERPERIUM |
|
|
| CHILDREN |
|
- Most children are at low risk of DVT.
|
These abbreviated guidelines are based on the THRIFT guidelines (Lowe et al
1992). The original Newcastle guideline was developed under the direction of:
- Professor Martin Eccles, Professor of Clinical Effectiveness, The
Clinical Effectiveness Unit, The Centre for Health Services Research,
University of Newcastle upon Tyne
- Lesley Hall, Research Associate, The Clinical Effectiveness Unit, The
Centre for Health Services Research, University of Newcastle upon Tyne.
Deep
venous thrombosis