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NHS TAYSIDE
CLINICAL
Prophylaxis of Venous
Thromboembolism
Author: Mr M Lavelle-Jones
Review Group:
Thromboprophylaxis
Protocol Development Group
Review Date: May 2007
Last Update: May 2005
Document No: CL/??
Issue No: 1
UNCONTROLLED WHEN PRINTED
Signed:
Executive Lead
(Authorised Signatory)
Medical Director
1
CONTENTS
PAGE No
1
Introduction
3
2
Risk Factors for VTE
4
3
Methods of Prophylaxis
5
4
General and Gynaecological Surgery
10
5
Orthopaedic Surgery and Trauma
11
6
Specialist Surgery
13
7
Spinal and Epidural Blocks
15
8
Medical Patients
16
9
Pregnancy and the Puerperium
18
10 Oral Contraceptives and HRT
21
11 Long Distance Travel
22
12 References
23
2
1
INTRODUCTION
This document draws together the Trust wide protocols for prophylaxis of venous thromboembolism. The
methods of thromboprophylaxis have been adjusted to suit the specific requirements of each medical and
surgical discipline. The protocols follows the template set out in the SIGN guideline “Prophylaxis of
Venous Thromboembolism” (SIGN Publication No 62, October 2002) together with more recent updates
(see Section 12) along with the views and expertise of the locally convened Thromboprophylaxis Protocol
Development Group. The membership of this group was as follows:
Mr Faz Alipour, Consultant Orthopaedic Surgeon, Ninewells Hospital
Mr Alan Boyd, Consultant Surgeon, Perth Royal Infirmary
Dr Matthew Checketts, Consultant Anaesthetist, Ninewells Hospital
Mr Alan Cook, Consultant Radiologist, Ninewells Hospital
Dr John Dick, Consultant Physician, Ninewells Hospital
Mr M Eljamel, Consultant Neurosurgeon, Ninewells Hospital
Mr Quentin Gardiner, Consultant Otolaryngologist, Ninewells Hospital
Dr Keith Gelly, Consultant Haematologist, Ninewells Hospital
Mr Chris Goodman, Consultant Urologist, Ninewells Hospital
Mr Bill Hadden, Consultant Orthopaedic Surgeon, Perth Royal Infirmary
Ms Karen Harkness, Pharmacist, Ninewells Hospital
Mr Michael Lavelle-Jones, Group Chairman, Consultant Surgeon, Ninewells Hospital
Dr Susan Morley, Consultant Dermatologist, Ninewells Hospital
Dr Jonathon O’Riordan, Consultant Neurologist
Dr Alan Shepherd, Consultant Physician, Ninewells Hospital
Dr Margaret Thompson, Consultant Obstetrician and Gynaecologist, Ninewells Hospital
SSN Gillian Hirst, Nursing Clinical Practice Council
3
2
RISK FACTORS FOR VENOUS THROMBOEMBOLISM (VTE)
All patients admitted to hospital with major trauma, major surgery (duration greater than 30 minutes) or
acute medical illness (requiring more than 3 days bed rest) should be individually assessed for risk of VTE
Assessment of individual risk should include
 Personal risk factors for VTE
 Past history of VTE
 Type of trauma, surgery, anaesthesia or medical illness
Individual prophylaxis should be chosen according to the balance of efficacy and risks and the patient’s
preferences
Routine screening for thrombophilias prior to risk situations such as the prescription of oral contraceptives
or hormone replacement therapy, pregnancy, or elective major surgery is not recommended.
TABLE 1
Age
RISK FACTORS FOR VENOUS THROMBOEMBOLISM
* <40 years – annual risk 1/10,000
* 60-69 years – annual risk 1/1000
* > 80 years – annual risk 1/100
Obesity
Varicose Veins
Previous VTE
Thrombophilias
Other Thrombotic States
Hormone Therapy
Pregnancy, puerperium
Immobility
3 times risk if obese BMI >= 30 kg/m2
1.5 times risk after major general/orthopaedic surgery
Low risk after varicose vein surgery
Recurrence rate 5% year, increased by surgery
Low coagulation inhibitors (antithrombin, protein C or S)
Activated protein C resistance
High coagulation factors (1, 11, VII, IX, XI)
Antiphospholipid syndrome
High homocysteine
Malignancy 7 times risk
Heart failure
Recent myocardial infarction/stroke
Severe infection
Inflammatory bowel disease, nephrotic syndrome
Polycythaemia, paraproteinaemia
Bechet’s disease, paroxysmal nocturia
Haemaglobinuria
Oral combined contraceptives
HRT, Raloxifine
Tamoxifen, 3 times risk
High dose progestogens, 6 times risk
10 times risk
Bed rest > 3 days, plaster cast, paralysis
10 times risk
Prolonged travel
Hospitalisation
Acute trauma, acute illness, surgery 10 times risk
Anaesthesia
General anesthesia twice risk of epidural/spinal
4
TABLE 2
RISK FACTOR STRATIFICATION
Level of Risk
LOW RISK
 Minor surgery; <40 years
 No risk factors
Prevention Strategy
Early mobilisation
MODERATE RISK
 Minor surgery with risk factors
 All surgery 40-60 years, no risk factors
LMWH (e.g. Dalteparin, 2,500 units daily)
GECS, or IPC
HIGH RISK
 All surgery > 60 years
 Surgery 40 – 60 years with risk factors
LMWH (e.g. Dalteparin, 5,000 units daily)
GECS or IPC



Hip or knee arthroplasty
Major trauma
Spinal cord injury
3
METHODS OF PROPHYLAXIS
3.1 General Measures
3.1.1.
Mobilisation and Leg Exercises
Immobility increases the risk of DVT about 10 fold.
Early mobilisation and leg exercises should be encouraged in patients recently immobilised.
3.1.2
Hydration
Haemoconcentration increases blood viscosity and reduces blood flow.
Adequate hydration should be ensured in immobilised patients.
3.2 Mechanical Methods
Unlike pharmacological methods, mechanical methods do not increase the risk of bleeding and may be
preferred in patients in whom the risk of bleeding may outweigh the antithrombotic efficacy of
pharmacological prophylaxis.
Mechanical methods are contraindicated in patients at risk of ischaemic necrosis eg those with critical limb
ischaemia or severe peripheral neuropathy.
Cross infection is a risk when devices are re-used.
3.2.1
Graduated Elastic Compression Stockings (GECS)





TABLE 2
GECS alone effect a threefold reduction in the risk of DVT.
GECS are effective in prophylaxis of asymptomatic DVT and symptomatic PE in surgical
patients.
Above knee GECS are preferred to below-knee stockings for prophylaxis of DVT.
GECS stockings are recommended for all grades of DVT risk in medical and surgical
patients. Whenever, practical GECS stockings should be applied pre-operative.
Table 2 summarises the contraindications and cautions for use of GECS.
CONTRAINDICATIONS AND CAUTIONS FOR THE USE OF GECS
5
Contraindications
 Massive leg oedema.
 Pulmonary oedema.
 Severe peripheral vascular disease.
 Severe peripheral neuropathy.
 Major leg deformity.
 Dermatitis, recent varicose vein surgery recent skin graft, gangrene.
 Limb size greater or smaller than specified instructions.
Cautions
 Select correct size.
 Apply carefully, aligning toe hole under toe.
 Check fitting daily for change in leg circumference.
 Do not fold down.
 Remove daily for no more than 30 minutes.
3.2.2
GECS plus Pharmacological Prophylaxis or in Combination with Intermittent Pneumatic Compression
(IPC)
Combination therapy reduces the incidence of asymptomatic DVT in surgical patients.
GECS may be combined with pharmacological prophylaxis or IPC in surgical patients to increase
efficacy in reducing the incidence of DVT.
3.2.3
Intermittent Pneumatic Compression
IPC devices alone appear to reduce the risk of asymptomatic DVT by one half.
IPC devices are effective in prophylaxis of asymptomatic DVT in surgical patients. The following
contraindications and cautions apply (Table 2A).
TABLE 2A
CONTRAINDICATIONS TO INTERMITTENT PNEUMATIC COMPRESSION
 Dermatitis, recent varicose vein surgery, recent skin graft, gangrene.
 Peripheral vascular disease.
 Massive oedema.
 Extreme limb deformity.
 Pre-existing DVT.
3.2.4
Mechanical Foot Pumps and Foot Impulse Technology
These devices have generally been designed to provide mechanical prophylaxis in patients who cannot
weight bear and are used primarily in orthopaedic surgery.
Mechanical foot pumps are effective in prophylaxis of asymptomatic DVT in orthopaedic surgery
patients.
3.3 Antiplatelet Methods
Aspirin and other antiplatelet drugs are highly effective at reducing major vascular effects in patients who
have established atherosclerotic disease and may provide some protection against VTE in hospitalised
patients.
However, the data regarding VTE prophylaxis is incomplete and a number of trials have shown no
significant benefit from aspirin therapy or have found it inferior to other prophylactic modalities.
Also, aspirin has been associated with a small but significant increased risk of major bleeding especially
when combined with other antithrombotic agents.
3.3.1 Aspirin in Surgical Patients
6
Aspirin is not generally recommended for the prophylaxis of VTE in patients undergoing
surgical procedures. Its use should only be considered in those patients in whom pharmacological
prophylaxis is contraindicated.
3.3.2
Aspirin in Medical Patients
The efficacy of aspirin in reducing total cardiovascular events (myocardial infarction [MI], stroke,
cardiovascular death) is clearly established in patients with acute MI and in acute ischaemic stroke and
outweighs the increased risk of bleeding.
The specific indications for aspirin therapy are outlined in Section 8.
3.3.3
Dose of aspirin, contraindications and cautions
Aspirin 150 mg/day commenced preoperatively and continued for 35 days after surgery. Specific
doses for treatment of medical conditions are outlined in Section 8.
Contraindications and cautions are outlined in Table 4.
TABLE 4 CONTRAINDICATIONS AND CAUTIONS OF ASPIRIN THERAPY
Contraindications
 Uncorrected bleeding disorders
o Haemophilias
o Oral anticoagulants
o Platelet count <70 x 109



Bleeding or potential bleeding
o Oesophageal varices
o Active peptic ulcer
o Recent (3 month) GI or intracranial bleed
o Intracranial aneurysm or angioma
Allergy
Heparin associated thrombocytopenia or thrombosis
Cautions
 Asthma
 Severe liver impairment, alcoholism
 Severe kidney impairment
 Major trauma or surgery to brail, eye or spinal cord
 Spinal or epidural block
 Anaemia (Hb< 10g/dl)
3.4 Unfractionated (UFH) and Low Molecular Weight Heparins (LMWH)
Unfractionated Heparin and several LMWHs are used for the prophylaxis of VTE and are usually given
subcutaneously in lower doses than are used for the treatment of established venous thromboembolism.
LMWH’s have a longer half-life than UFH so can be given as once daily injections, compared to 8 – 12
hourly for UFH.
Heparin prophylaxis should be given for at least 5 days or until hospital discharge if earlier. Prolonged
prophylaxis may be indicated in patients with continued illness and immobility and in orthopaedic patients
(see Section 5).
Post discharge prophylaxis should be discussed with the primary care team prior to the patient’s discharge
from hospital.
3.4.1 Efficacy and Safety of Unfractionated Heparin in Surgical Patients
7
UFH significantly reduces the incidence of asymptomatic DVT, symptomatic DVT and PE and fatal
PE in surgical patients. Although there is a small increase in major bleeding there is no increase in
fatal bleeding.
3.4.2 Efficacy and Safety of LMWHs in Surgical Patients
Subcutaneous LMWH has similar prophylactic efficacy against VTE and risk of bleeding to UFH.
3.4.3 Efficacy and Safety of UFH and LMWH in Medical Patients
Similar reductions in VTE are seen in medical patients.
Subcutaneous low dose heparin (UFH or LMWH) is effective in prophylaxis of asymptomatic and
symptomatic VTE in surgical and medical patients.
3.4.4 Administration, Dosage and Coagulation Monitoring
Both UFH and LMWH are given subcutaneously. The risk of wound haematomas can be minimised
by avoiding injection sites close to wounds.
Dose of UFH
 The dose of UFH is 5,000 units 8 – 12 hourly or 7,500 units 12 hourly
Dose of LMWH
 The dose varies according to the LMWH used.
 Dalteparin (Fragmin) is the LMWH of choice within this health care trust. The recommended
dose for prophylaxis is:
Moderate risk:
 2,500 units 1-2 hours before surgery them 2,500 daily for 5 days or until discharged
High risk:
 2,500 units 1-2 hours before surgery then 2,500 units 8-12 hours later then 5,000 units daily
for 5-7 days or 5,000 units evening before surgery , then 5,000 units on the following
evening then 5,000 units daily for 5-7 days
If an epidural/spinal anaesthetic is planned the regime is modified according to the protocol outlined
in Section 7.
Monitoring the anticoagulant effect of UFH or LMWH is not usually required. Exceptions are:
 high risk pregnancy
 complications such as bleeding or accidental overdose
 patients with renal failure who require high dose (therapeutic) doses of LMWH
3.4.5 Monitoring platelet count
Immune mediated heparin induced thrombocytopenia (HIT) usually occurs 5-20 days after starting
treatment. It can occur at any dose of UFH or LMWH. HIT should be considered in any patient
whose platelet falls by 50% or more.
In order to detect heparin induced thrombocytopenia, a baseline platelet count should be obtained and
the platelet count monitored in all patients receiving heparin for 5 days or more.
Heparin should be stopped if thrombocytopenia develops or if the platelet count drops by 50% or
more.
Warfarin is a suitable alternative to heparin in patients who develop HIT once the platelet count has
recovered to >100 x 109/L provided there is no surgical contraindication.
8
3.4.6 Monitoring of Bone Density
Prolonged use of prophylactic heparin has been associated with a reduction in bone density in some
patients. This need only be considered in patients requiring heparin therapy exceeding 12 weeks
duration
3.4.7 Reversal of Heparin Anticoagulation
It is usually sufficient to stop heparin if mild bleeding occurs as the half-life of UFH and LMWH is
short. If severe bleeding occurs Protamine Sulphate should be given. Protamine is less effective in
reversal of LMWH anticoagulation. Specialist advice can be obtained from on-call Haematologist.
3.5, 3.6 & 3.7 Herparinoids, Hirudins, Pentasaccarides
The routine use of these agents in the prophylaxis of VTE is not currently recommended for patients in this
Healthcare Trust.
3.8 Oral Anticoagulants
Warfarin is not normally used for prophylaxis of VTE because it requires daily monitoring by the
Internationalised Normalised Ratio (INR) of the prothrombin time and because it increases the risk of
bleeding after trauma, surgery as well as spinal or epidural anaesthesia.
Contraindications and cautions include:
 bleeding disorders
 bleeding or potentially bleeding lesions
 spinal or epidural anaesthesia
 pregnancy (due to fetal toxicity)
In patients who are already receiving long term anticoagulant therapy who are immobilised by illness,
trauma or surgery continuation of oral anticoagulants may be appropriate prophylaxis.
Where the risks of bleeding during or after surgery give rise to concern, oral anticoagulant therapy may be
discontinued preoperatively. Once the INR is <2 prophylaxis should be continued using UFH or LMWH in
combination with mechanical prophylaxis. Oral anticoagulants can be resumed once the risk of bleeding is
no longer of concern. UFH/LMWH should be continued until the INR returns to the appropriate therapeutic
range.
3.9 Dextrans
These agents are not generally recommended for the prophylaxis of VTE for patients in this Healthcare
Trust.
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4
GENERAL AND GYNAECOLOGICAL SURGERY
4.1 Risk Factors for VTE
Patients undergoing major (e.g. duration over 30 minutes) general or gynaecological surgery, who are
aged 40 years or over, or who have other risk factors (Table 1) have a significant risk of both
asymptomatic and symptomatic VTE
4.2 Heparins
LMWH (Deltaparin) is the first line prophylaxis against DVT in patients undergoing major general or
gynaecological surgery who are at significant risk of VTE. The risk should be stratified as outlined in
Table 1 and 2.
Dalteparin (Fragmin) is the LMWH of choice within this Healthcare Trust. The recommended dose for
prophylaxis is:
Moderate risk:
 2,500 units 1-2 hours before surgery them 2,500 daily for 5 days or until discharged.
High risk:
 2,500 units 1-2 hours before surgery then 2,500 units 8-12 hours later then 5,000 units daily
for 5-7 days or 5,000 units evening before surgery , then 5,000 units on the following evening
then 5,000 units daily for 5-7 days.
If an epidural/spinal anaesthetic is planned the regime is modified according to the protocol
outlined in Section 7.
4.3 Mechanical Methods
4.3.1
Graduated Elastic Compression Stockings
In patients undergoing major general or gynaecological surgery above knee GECS can be
substituted for LMWH when this agent is contraindicated
Above knee GECS should be combined with LMWH in patients undergoing major general or
gynaecological surgery especially in those patients who are at moderate/high risk due to the
presence of multiple risk factors
4.3.2
Intermittent Pneumatic Compression
In patients undergoing major general or gynaecological surgery intermittent pneumatic
compression (IPC) followed by above knee GECS can be substituted for LMWH when this
agent is contraindicated.
IPC followed by GECS can be used in combination with LMWH in patients at high risk
of DVT.
4.4 Antiplatelet Drugs
Routine use of aspirin is not recommended. It is an alternative to LMWH when this agent is
contraindicated but should be used in combination with the mechanical methods outlined above.
4.5 Dextrans
These agents are not generally used in the prophylaxis of DVT.
10
4.6 Oral Anticoagulants
This agent is not routinely used in the prophylaxis of DVT due to the increased risk of bleeding.
5
ORTHOPAEDIC SURGERY AND TRAUMA
5.1
Total Hip or Knee Replacement
All patients undergoing hip or knee arthroplasty are enrolled in the Scottish National
Arthroplasty Register.
5.1.1
Mechanical Prophylaxis
Patients undergoing total hip or knee arthroplasty or any other major elective orthopaedic
surgery are considered for mechanical prophylaxis using either foot pumps or calf pumps. The
use of these devices is generally reserved for high-risk patient groups or patients for whom
chemoprophylaxis is contraindicated. If these devices are to be used as a first line method of
prophylaxis it is at the discretion of the treating consultant.
Graduated elasticated compression stockings are used at the Consultant’s discretion
5.1.2
Antiplatelet Drugs (aspirin)
Aspirin is not used as a sole means of DVT prophylaxis. It is only to be used in conjunction
with mechanical prophylaxis (foot/calf pump) in patients in whom Heparins are contraindicated
5.1.3
Heparins
LMWH (Dalteparin) is the first line prophylaxis used against DVT in hip arthroplasty (and any
major knee or major elective orthopaedic surgery). An initial dose of Dalteparin 2,500 units
is commenced either within 6 hours after the end of surgery or after removal of the
epidural catheter if one has been inserted by the Anaesthetist; thereafter a 5,000 units
daily dose is used.
If an epidural catheter remains in situ during the post-operative period to provide pain relief
mechanical prophylaxis (foot/calf pump) is continued until the catheter is withdrawn.
LMWH prophylaxis is continued for a period between 5 – 10 days depending on the patients
progress or until they are discharged. If a patient requires extended anti-DVT prophylaxis
following surgery either Warfarin or Aspirin are used for a period of up to 6 weeks
5.1.4
Oral Anticoagulants
Warfarin is not used routinely unless the patient has already been on Warfarin and this has
been stopped pre-operatively. If a patient requires extended anti-DVT prophylaxis following
surgery Warfarin may be used for a period of up to 6 weeks.
5.1.5
Summary
Patients undergoing total knee or hip arthroplasty or any other elective major orthopaedic
procedure should receive chemo-prophylaxis unless contraindicated. Low molecular
fractionated heparin (Dalteparin) is the first choice. Mechanical prophylaxis is used in addition
in high-risk patient groups or at the discretion of the treating consultant. Aspirin is only used in
conjunction with mechanical prophylaxis when Heparins are contraindicated. Presently the use
of graduated elasticated calf compression stockings is at the discretion of the consultant. In
those patients who require extended chemoprophylaxis Warfarin or Aspirin is used for up to 6
weeks.
11
5.2
Hip Fracture Surgery
Patients undergo early surgery on a scheduled basis within 24 hours wherever possible to reduce
the risk of DVT and fatal PE after hip fracture
5.2.1
Mechanical Prophylaxis
Mechanical prophylaxis (foot/calf pump) is considered in high-risk patients or at consultant
discretion. Graduated elasticated compression stockings are also used at consultant’s
discretion.
5.2.2
Antiplatelet Drugs (Aspirin)
Aspirin is not routinely used in patients with hip fracture. It can be combined with mechanical
prophylaxis in patients in whom Heparins are contraindicated. It is continued for 6 weeks postoperatively.
5.2.3
Heparins
LMWH (Dalteparin) is the first line of prophylaxis against deep vein thrombosis in hip fracture
patients. It is normally commenced within 6 hours after surgery (2,500 units) and continues for
at least 10 days (5,000 units) until the patient is fully mobile or discharged.
5.2.4
Oral anti-coagulants and Dextrans
These agents are not routinely used. Patients who have been admitted on Warfarin have this
medication stopped prior to surgery and restarted once the patient is no longer at risk of bleeding.
5.3
Knee Arthroscopy
Routine prophylaxis is not used in patients undergoing knee arthroscopy.
5.4
Trauma
These patients are at high risk of VTE. 2,500 units Dalteparin should be administered as soon as
possible after surgery/admission and continued (5,000 units daily) for 5 days or until fully mobile.
LMWH should be combined with mechanical methods in these patients and LMWH should only be
omitted if there is a bleeding risk.
12
6
SPECIALIST SURGERY
6.1
Urological Surgery
6.1.1
Major or Open Urological Procedures
Patients undergoing major or open urological surgery have a similar risk to patients undergoing
general or gynaecological surgery and should receive similar prophylaxis. (See Section 4).
The preferred method of prophylaxis in patients undergoing major or open urological
procedures who are at significant risk of VTE (age over 40 or other risk factors [see Table 1
and 2]) is LMWH (Dalteparin) either alone or in combination with mechanical prophylaxis
(See section 4).
In patients in whom LMWH is contra-indicated, mechanical prophylaxis either GECS alone or
IPC followed by GECS or may be used.
6.1.2
Trans Urethral Resection of Prostate
In patients undergoing TURP who have no risk factors, early mobilisation alone or in
combination with GECS will provide adequate prophylaxis. In patients undergoing TURP at
increased risk of VTE, GECS in combination with IPC should be used. Where there are
multiple risk factors, the addition of LMWH should be considered balanced against the
increased risk of bleeding.
6.2
Neurosurgery
VTE is common after neurosurgery. Because of the potential consequences of intracranial or
intraspinal bleeding mechanical prophylaxis is preferred.
Neurosurgical patients should receive antithrombotic prophylaxis using IPC alone or in
combination with GECS.
VTE is frequent in patients with acute spinal cord injury
Patients with acute spinal cord injury should receive antithrombotic prophylaxis with LMWH
(eg Dalteparin 5,000 units daily) converting to Warfarin for long term prophylaxis with a target
INR of 2.5 (range 2.0 – 3.0). IPC should be used in those patients in whom anticoagulation is
contraindicated.
6.3
Cardiothoracic Surgery
Patients undergoing major cardiothoracic surgery have a similar risk of VTE to patients
undergoing major general or gynaecological surgery. Presently no patients undergo
cardiothoracic surgery in Tayside.
6.4
Peripheral Vascular Surgery
6.4.1
Major Vascular Surgery
Patients undergoing major vascular surgery have a similar risk of VTE to patients undergoing
major general or gynaecological surgery and should receive prophylaxis as outlined in Section
4.
Mechanical prophylaxis is contraindicated in patients with severe peripheral vascular disease as
it can cause skin necrosis.
13
In patients with critical limb ischaemia or those who undergo major peripheral vascular surgery
or amputation subcutaneous low dose fractionated Heparin (eg Dalteparin 5.000 units/daily) is
recommended.
Aspirin (75-300 mg/day) should be given or resumed 6 hours after surgery and continue long
term.
6.4.2
Varicose Vein Surgery
The risk of VTE after varicose vein surgery is low.
Post-operative GECS are recommended in patients undergoing varicose vein surgery who have
no additional risk factors.
Subcutaneous LMWH (eg Dalteparin 2,500 units/daily) plus GECS should be used in patients
with additional risk factors.
6.4.3
Carotid Surgery
These patients are usually freely anticoagulated peri-operatively, 5,000 units Dalteparin daily is
recommended commencing the evening following surgery.
6.5
Minimal Access Surgery
The risk of VTE in patients undergoing minimal access surgery is unclear. The benefits of
early mobilization may be offset by impaired venous return produced by the
pneumoperitoneum during the procedure.
Until the risk is defined patients undergoing laparoscopic surgery should be considered to have
the same risk of VTE to patients undergoing major general or gynaecological surgery and
should receive similar prophylaxis (see section 4).
6.6
Otolaryngology
The risk of VTE is very low in patients undergoing otolaryngological procedures.
No prophylaxis is required in patients undergoing uncomplicated minor surgery, patients <40
years of age, or in patients without risk factors (see Tables 1 and 2).
GECS alone or IPCS followed by GECS are recommended in patients undergoing in all
patients undergoing minor surgery who have risk factors for VTE; in all patients aged 40 -60
years undergoing minor surgery, or any patient undergoing major surgery with no risk factors
Low dose fractionated heparin (Dalteparin) is recommended in all patients undergoing major
surgery who have additional risk factors for VTE (see Tables 1 and 2).
6.7
Eye Surgery
The incidence of VTE in ophthalmology is extremely low.
GECS alone or IPCS followed by GECS are recommended in patients undergoing prolonged
intraocular procedures with no risk factors.
Low dose fractionated heparin (Dalteparin) is recommended in all patients undergoing
prolonged intraocular procedures who have additional risk factors for VTE (see Tables 1 and
2).
14
6.8
Plastic Surgery
Fatal VTE is uncommon in patients undergoing plastic surgery procedures. In patients with risk
factors for VTE should receive similar prophylaxis to patients undergoing general or
gynaecological surgery (see Section 4).
Burns patients who have one of the following additional risk factors for VTE, age >60 years,
obesity, extensive or lower limb burns, lower limb trauma or prolonged immobility should
receive prophylaxis with LMWH (e.g. Dalteparin 2,500 UNITS daily).
7
SPINAL AND EPIDURAL BLOCK
7.1
Efficacy in Prophylaxis of VTE in Surgical Patients
Spinal or epidural anaesthesia reduces the incidence of VTE by 50% compared to general
anaesthesia and may be preferred to general anaesthesia where appropriate and feasible.
7.2
Risk of Vertebral Canal Haematoma when Combined with Pharmacological Prophylaxis of
VTE
The incidence of spinal canal haematoma following LMWH varies from 1 in 2,250,000
(European experience) to 1 in 40,000 (United States experience) and varies with the dosage
used and the timing of administration.
7.2.1
Anticoagulants
Full anticoagulation is an absolute contraindication to spinal or epidural block The INR should
be 1.5 or lower for institution of a block or removal of a catheter.
7.2.2
Unfractionated Heparin
A transient elevation in APTT may occur after subcutaneous administration of a 5,000 or 7,500
units dose of UFH. It is preferable not to institute a spinal or epidural block or to remove a
catheter within 4 – 6 hours of a dose. The platelet count should be checked before the block is
instituted or before catheter removal to exclude a heparin induced thrombocytopenia.
7.2.3
LMWH
Standard European dose regimes are not associated with any increased risk of vertebral canal
haematoma provided the block is not instituted or the catheter withdrawn within 10-12 hours of
LMWH administration.
7.2.4
Antiplatelet Agents (Aspirin)
There is no evidence that aspirin alone increases the risk of vertebral canal haematoma.
7.2.5
Recommendations
The following precautions should be taken when instituting spinal/epidural block, when
removing an epidural catheter or performing a lumbar puncture.
Unfractionated Heparin
 Administer 4-6 hours before block.
 Or delay first dose until after block performed or after surgery.
LMWH
 Administer 10 – 12 hours before block.
 Or give about 1-2 hours after the block.
15
In major hip surgery there is good evidence that omitting the preoperative/pre block dose of
LMWH does not lead to an increased risk in VTE and may reduce the risk of bleeding
Warfarin
 If INR <1.5 proceed normally.
 If INR >1.5 consider alternative anaesthetic technique if surgery is urgent, or delay
surgery.
If there has been technical difficulty or bleeding encountered during the block procedure
consideration should be given to omitting or delaying the next dose of chemical
thromboprophylaxis
If chemical prophylaxis is omitted in patients undergoing a spinal/epidural block a mechanical
method should be used instead
8
MEDICAL PATIENTS
Most cases of VTE are triggered by causes other than surgery and most fatal VTE occur in medical
patients.
8.1
Acute Myocardial Infarction
8.1.1
Antiplatelet Drugs and Thrombolytic Therapy
It is strongly recommended that all patients with clinically suspected evolving acute MI who
are not already receiving aspirin should be given Aspirin 300 mgs stat then 75 mg daily
(currently under review by SIGN).
It is strongly recommended that all patients with clinically suspected evolving acute MI should
be considered for thrombolytic therapy in accordance with the Coronary Care Unit therapeutic
schedule. .
8.1.2
Anticoagulants
Heparin is associated with an increase in bleeding in the presence of Aspirin and leads to only a
minor reduction in fatal VTE.
Heparin should not be used routinely in addition to aspirin in acute MI, but should be reserved
for patients at increased risk of VTE (Tables 1 and 2).
Some patients with acute established MI are at increased risk of VTE. Those patients with the
following risk factors should be fully anticoagulated with Heparin followed by Warfarin:









Large anterior Q wave infarction
Severe left ventricular dysfunction
Congestive heart failure
History of systemic or pulmonary embolism
Thrombophilia
Echocardiographic evidence of mural thrombus
Persistent atrial fibrillation
Prolonged immobilisation
Marked obesity
These patients should be considered for anticoagulation with full dose Heparin (target APTT
ratio 2.0, range 1.5 – 2.5) followed by Warfarin (target INR 2.5 range 2.0 – 3.0) for up to 3
months depending on the physician’s estimate of the risk/benefit ratio in the individual patient.
16
In other patients with acute MI, and in patients as defined above in whom the bleeding risks of
full dose anticoagulation are judged to outweigh the benefits, prophylaxis of VTE with low
dose subcutaneous unfractioned Heparin (7,500 units 12 hourly) for seven days or until
ambulant, should be considered
8.1.3
Mechanical Prophylaxis
Compression stockings may be considered in patients with acute MI who are at increased risk
of VTE when heparin prophylaxis is contraindicated.
8.2
Acute Stroke
8.2.1
General Measures
Patients with stroke should be mobilised as early as practicable and measures taken to ensure
good hydration.
8.2.2
Mechanical Prophylaxis
Selected use of graduated compression stockings may be justified for some high-risk patients.
Compression stockings are preferred for patients with haemorrhagic stroke.
8.2.3
Antiplatelet Drugs (Aspirin)
Early treatment with Aspirin (150-300 mg/day) is recommended in acute ischaemic stroke,
starting as soon as intracranial haemorrhage is excluded by CT or MR brain scanning in order
to reduce the risk of fatal VTE
Aspirin can be given by naso-gastric tube or rectally (using 300 mg suppositories) for those
who are unable to swallow.
8.2.4
Heparins
LMWH (Dalteparin) may be considered in patients with ischaemic stroke who are at increased
risk of VTE (Table 1) and who are at lower than average risk of haemorrhagic complications.
8.3
Other Medical Patients
Immobilised patients in medical wards are at increased risk of VTE and should be considered for
prophylaxis. Certain groups of patients are at particular risk (Table 1).
8.3.1
Heparins
Medical patients who are immobilized in hospital due to acute illness, especially those with
heart failure, respiratory infections, diabetic coma, inflammatory bowel disease, nephrotic
syndrome, or who are in intensive care should be considered for VTE prophylaxis using
LMWH (Dalteparin) dose 5,000 units once daily.
8.3.2
Mechanical Methods
In medical patients at significant risk of VTE in whom heparin prophylaxis is contraindicated
GECS should be considered.
8.4 Cancer Patients
As noted above, immobilised cancer patients should be considered for prophylaxis. In addition:
17


Mini dose Warfarin (1mg/day, no INR monitoring) is recommended for prophylaxis of thrombosis
in cancer patients with central venous catheters.
Low dose Warfarin (target INR 1.6 range 1.3 – 1.9) is recommended for prophylaxis of thrombosis
during chemotherapy in stage IV breast cancer.
9 Pregnancy and the Puerperium
There is a ten-fold increase in VTE throughout pregnancy and the puerperium. The same risk factors
that increase risk in non-pregnant patients apply (Table 1) in addition to specific risk factors such as
pre-eclampsia and operative delivery.
During pregnancy and the puerperium the following general principles apply:
 Warfarin and other coumarins should be avoided if possible especially between 6 – 12 weeks and
after 36 weeks gestation because of the risk of teratogenic effects.
 LMWH is preferred to UFH in pregnancy because there is more safety data.
 All pregnant women should be regularly assessed for VTE risk factors.
9.1 Antenatal Thrombosis Risk Assessment
A risk assessment should be made during the first antenatal visit. Because VTE can occur early in
pregnancy in the presence of coexisting risk factors thromboprophylaxis if indicated should be started
as early as possible during the pregnancy.
All pregnant women should be offered screening for thrombophilias if any of the factors listed in Table
4 are identified.
TABLE 4 RISK FACTORS FOR THROMBOPHILIA IN PREGNANT WOMEN
 VTE before age of 45
 Recurrent VTE/thrombophlebitis
 Venous thrombosis in an unusual site eg axillary
 Arterial thrombosis before age of 40 years
 First or second generation relatives with thrombophilia
 Clear family history of VTE
 Unexplained prolonged activated partial thromboplastin time
 Selected patients with recurrent foetal loss, ITP, SLE
9.2 Previous VTE No Identifiable Thrombophilias
In all women with a VTE event in a previous pregnancy or during combined oral contraceptive use
(COC) antenatal thromboprophylaxis should be used.
In all women with previous idiopathic VTE antenatal prophylaxis should be started as soon as possible.
Women in whom a previous VTE occurred in association with a temporary risk factor which is no
longer present (e.g. trauma) with no current risk factors other than pregnancy do not require antenatal
LMWH prophylaxis but should be considered for GECS.
9.2.1 Dosage and Administration
Dalteparin is the pharmacological agent of choice in this Healthcare Trust.
The dose of subcutaneous LMWH varies with body weight (e.g. 40 – 70 Kg 2,500 units Dalteparin
daily;
>80 Kg 5,000 units Dalteparin/day)
GECS may be combined with LMWH according to preference.
18
9.3 Long Term Anticoagulants or Known Heritable Thrombophilia
Some patients within this group are at especial risk. They are stratified as follows:
9.3.1
High risk of clinical VTE
*
women on long term anticoagulant thromboprophylaxis for VTE
*
women who have antithrombin deficiency
These patients should be switched to LMWH as soon as pregnancy is confirmed. Prophylaxis
should be based on early pregnancy weight (eg Dalteparin 50-100 units/kg 12 hourly)
9.3.2
Moderately Increased Risk of VTE
 Women with a previous VTE who have a thrombophilia other than the above.
 Women with no previous VTE who are protein C deficient.
Prophylaxis should be given with LMWH (eg Dalteparin 5,000 units/day).
9.3.3
Slightly Increased Risk for VTE
 Women with no history of VTE with a known heritable thrombophilic defect (from family
history).
These women do not routinely require antenatal thromboprophylaxis but should be offered
thromboprophylaxis in the puerperium. GECS may be considered.
9.4 Antiphospholipid Syndrome
Women with antiphospholipid syndrome are at risk of miscarriage related to placental thrombosis and
are also at increased risk for VTE. The following recommendations apply to these patients:
 Women with antiphospholipid syndrome and recurrent miscarriage should receive
thromboprophylaxis from the diagnosis of pregnancy with LMWH (eg Dalteparin 5,000 units/day)
and low dose aspirin (75 mg/day).
 Women with antihospholipid syndrome who have already had a VTE should also receive LMWH
(eg Dalteparin 5,000 units/day) and low dose Aspirin (75 mg/day).
 Low dose Aspirin (75 mg/day) should be used in all other women with antiphospholipid syndrome
antenatally to reduce the risk of complications and should receive postpartum prophylaxis .
9.5 Caesarian Section
All women should undergoing Caesarian Section should be assessed for risk of VTE..
9.5.1
Risk Factors for Patients Undergoing Caesarian Section
Patients can be categorised as follows:
Low Risk:
 Elective Caesarian Section (uncomplicated pregnancy)
Moderate Risk:
 Emergency Caesarian Section
 Age >35 years
 Obesity (>80 Kg)
 Para 4 or more
 Gross varicose veins
 Current infection
 Pre-eclampsia
 Immobility prior to surgery (>4 days)
 Major intercurrent illness (e.g. heart or lung disease, inflammatory bowel disease,
nephrotic syndrome)
19
High Risk:
 3 or more of the above risk factors
 extended pelvic or abdominal surgery (eg caesarian hysterectomy)
 antiphospholipid antibody
9.5.2
Management of Different Risk Groups
Low Risk Patients
 Women undergoing elective Caesarian Section with uncomplicated pregnancy and no other
risk factors require only early mobilization and adequate hydration.
Moderate Risk Patients
 These women should receive prophylaxis using subcutaneous LMWH (eg Dalteparin 2,500
units daily) and GECS.
 In pregnant women who have required antenatal thromboprophylaxis LMWH should be
stopped when labour starts. Generally, an epidural or spinal should not be given for 10-12
hours after LMWH administration
High Risk Patients
 Women at high risk should receive subcutaneous LMWH (eg Dalteparin 5,000 units/day)
and GECS. The following practical considerations apply:



LMWH should commence 1 hour after Caesarian Section in women undergoing spinal
anaesthesia.
If an epidural block is used LMWH should be given one hour after removal of the
catheter.
Prophylaxis should continue until the patient is fully mobile or until post operative day
5 in high risk patients
In pregnant women who have required antenatal thromboprophylaxis LMWH should be
stopped when labour starts. Generally, an epidural or spinal should not be given for 10-12
hours after LMWH administration.
9.6 Delivery and Postnatal Prophylaxis
9.6.1
Management of the Delivery
In pregnant women who have required antenatal thromboprophylaxis LMWH should be
stopped when labour starts. Generally, an epidural or spinal should not be given for 10-12
hours after LMWH administration
LMWH can be administered or re-administered 3 hours after a traumatic epidural or spinal
anaesthesia, or removal of an epidural catheter.
9.6.2
Management of the Puerperium
The risk of VTE in the postnatal period can be calculated using the scoring system outlined
below:
0
1
Points
Age
<35 yrs
36-40 yrs
Weight
<80 Kg
2
>40 yrs
100-120 Kg
BMI >30
>120 Kg
3
Delivery
Vaginal
Other
Para 4 or more
Gross varicose veins
Current infection
Pre-eclampsia
Immobility >4 days
Major current illness
Sickle cell disease
Extended major
20
BMI >35
pelvic/abdominal surgery
Previous VTE
Thrombophilia
Paralysis lower limbs
Antiphospholipid antibody
eg A 37 year old woman weighing 72 Kg undergoing emergency Caesarian Section for pre
eclampsia scores 5 points (1+0+3+1).
9.6.3
Thromboprophylaxis Regimes in the Puerperium
The appropriate regime is calculated from the points scored using the above risk assessment
profile:
Points
0
1
2
3 or more
Regime
Early mobilization and hydration
Early mobilization and hydration
Early mobilization and hydration
GECS stockings
Consider LMWH (eg Dalteparin 5,000 units/daily) for
5 days or until fully mobile
Early mobilization and hydration
GECS stockings
LMEH (eg Dalteparin 5,000 units/daily) for 5 days or
until fully mobile
Postpartum the first dose of subcutaneous LMWH should be given 3-6 hours after delivery.
Anticoagulation should be continued for 6 weeks in patients with previous DVT or thrombophilias.
Otherwise thromboprophylaxis should be continued for 5 days.
In patients who require prolonged anticoagulation LMWH can be replaced by Warfarin starting on
the first or second postpartum day. LMWH can be withdrawn when the INR reaches the target
range (2.0-3).
There is no contraindication to breast feeding when the mother is being treated with LMWH,
Warfarin or other coumarins
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CONTRACEPTIVES AND HORMONE REPLACEMENT THERAPY
10.1
Oral Contraceptives
The relative risk of VTE in women using levonorgestrel or northisterone containing combined oral
contraceptives (COC) is increased threefold. COC’s containing gestodene or desogestrel are associated
with a six-fold increase in VTE. In absolute terms this means an increase in risk of VTE from 5 per
100,000 woman years to 10 and 15 per 100,000 years respectively.
10.1.1 Combined Oral Contraceptives and Surgery
The risk of post-operative VTE is doubled for COC pill users versus non-users. This small
absolute risk must be balanced against the risks of stopping the pill prior to surgery including
the risks of unwanted pregnancy, the effects of surgery/anaesthesia on pregnancy and the risks
of termination.
10.1.2 Progestagen Only Contraceptives
There is no evidence that low dose progestogen-only contraceptives are associated with an
increased risk of VTE.
21
10.1.3 Recommendations
Combined oral contraceptives should be discontinued at least 4 weeks before major surgery
where immobilization is expected. Alternative means of contraception should be discussed in
this group of patients.
Combined oral contraceptives do not need to be discontinued before minor surgery which does
not lead to immobilisation.
Progestogen only methods, or the Mirena need not be discontinued prior to surgery even when
immobilisation is expected.
Specific antithrombotic prophylaxis in all these patients should be chosen according to the
overall risk factors (Table 1 and 2), the type of procedure undertaken and the anaesthetic
technique used.
VTE prophylaxis (Dalteparin + GECT + IPC) should be used routinely in patients using COC
who undergo emergency surgery
10.1.4 Hormone Replacement Therapy and Raloxifene
Like COCs oral oestrogen containing hormone replacement therapy (HRT) increases the risk of
VTE threefold. This translates to an absolute risk of 30 per 100,000 women years compared to
10 per 100,000 women years for non-users.
HRT should be considered a risk when assessing a woman pre-operatively
HRT does not require to be routinely stopped prior to surgery provided that routine prophylaxis
such as LMWH (eg Dalteparin 2,500 UNITS daily), with or without GECS, is used.
11 LONG DISTANCE TRAVEL
The risk of VTE appears higher in patients with known risk factors (Table 1) and with flights
exceeding 3,000 miles.
To minimize the risk of thrombosis when traveling long distances, especially by air (eg more than 4
hours) all travelers should be advised to:
 ensure good hydration.
 restrict alcohol and coffee intake.
 regularly carry out leg exercises and take occasional walks during travel.
In patients at high risk of thrombosis such as a recent VTE, recent major surgery, trauma or
immobilizing medical illness, the following prophylactic measures should be considered:
 GECS.
 Single dose aspirin (150 mg) before travel.
 Single injection of LMWH (e.g. Dalteparin 2,5000 units) before travel.
The risk of bleeding (as a result of prophylaxis) which is difficult to treat on a long haul flight should
be considered.
22
12
REFERENCES
Prophylaxis of venous thromboembolism; SIGN Publication No 62, October 2002.
Prevention of venous thromboembolism; The seventh ACCP conference on antithrombotic and
thrombolytic therapy; CHEST 2004; 126:33S-400S.
Venous thromboembolism and hormonal contraception; Royal College of Obstetricians and
Gynaecologists; Guideline No 40, October 2004.
Venous thromboembolism and hormone replacement therapy; Royal College of Obstetricians and
Gynaecologists; Guideline No 19, January 2004.
New concepts in orthopaedic thromboprophylaxis; Warwick D; Journal of Bone and Joint Surgery; 866,788-792, August 2004.
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