Clinical Surgery in General > Perioperative Care > Thromboprophylaxis

1. MuhammadAbdelghani
Prophylaxis of Thromboembolic
Disease
Knowledge Level
A B
2 4

2. Epidemiology
Preoperative management of the surgical patient
includes planning to avoid fatal complication of
pulmonary thromboembolism.
Clinically significant but non-fatal thromboembolism
occurs in about 1:100 postoperative patients.
Fatal pulmonary embolism occurs in 1:1000.

3. Epidemiology
Risk of DVT without thromboembolic
prophylaxis:
25% for major general and cardiovascular surgery
40–80% for major hip and knee surgery

4. Pulmonary Embolism (PE)
Pulmonary emboli:
are a major cause of mortality for surgical
patients.
account for 10% of inpatient deaths in the
UK.

5. Pulmonary Embolism (PE)
Origin of the pulmonary embolus:
Usually thrombosis in the veins of calf muscles.
Thrombosis may spread to iliofemoral and pelvic veins.
The development of venous thrombosis in these
veins is usually silent and may only manifest itself as
an episode of PE.
Hence the emphasis on prophylaxis to prevent this
serious complication.

6. Risk Factors for PE
Age >40 years
Obesity
Immobilisation
Previous DVT
General anaesthetic
Major abdominal/orthopaedic surgery
Pregnancy/postpartum
Malignancy, particularly ovarian and pancreatic cancer
Hypercoaguable states, e.g., deficiency of antithrombin 3, protein
C or protein S
Medical illness, incl. myocardial ischaemia, respiratory
insufficiency.

7. Risk Groups
Surgical patients can be divided into low-,
medium- and high-risk groups for venous
thrombosis and pulmonary embolism.

8. Risk Groups
Typical low-risk patient:
Age <40 years
Surgery lasting <30 min, particularly avoiding
general anaesthetic
Rapidly mobilised postoperatively
No other risk factors

9. Risk Groups
Typical moderate-risk patient:
Age >40 years
Moderate obesity
Need abdominal operation requiring general
anaesthetic
One other risk factor

10. Risk Groups
Typical high-risk patient:
Middle-aged or elderly, undergoing major
surgery (orthopaedic or cancer surgery)
Need prolonged mobilisation
May have pelvic trauma or pelvic surgery
May have suffered orthopaedic trauma
generally: e.g., fractured neck of femur;
Multiple risk factors.

11. Risk Groups
All moderate- to high-risk patients
should receive prophylaxis.
It is not easy to categorise every
patient.
When in doubt, institute
thromboprophylaxis.

12. Methods of Prophylaxis
General
Early ambulation
Use of venous support compression stockings,
particularly where local venous insufficiency
problems exist in the limbs
Intermittent pneumatic calf stimulation during
operations under general anaesthetic.
These methods are sufficient prophylaxis for fit low-risk
patients.

13. Methods of Prophylaxis
Moderate- and High-Risk Patients
These patients require pharmacological
intervention with antithrombotic drugs.
Low-dose subcutaneous heparin
Low-molecular-weight heparin (LMWH)
Anticoagulants (e.g. warfarin)
Antiplatelet agents

14. Methods of Prophylaxis
Moderate- and High-Risk Patients
Low-dose subcutaneous heparin:
Effective in reducing thrombosis in the peripheral veins.
Dose: 5000 units bd subcutaneously.
Heparin at this dose does not alter standard coagulation screening studies.
Main complications:
Bruising and local wound haematoma if injection is given close to operative
site.
Allergic thrombocytopaenia.
This may be associated with thrombosis.
Heparin must be ceased.

15. Methods of Prophylaxis
Moderate- and High-Risk Patients
Low-molecular-weight heparin
(LMWH):
Given as a single daily dose.
Advantages: As effective as heparin in
preventing thrombosis, with fewer platelet
side-effects.
Disadvantages: LMWH is expensive and is
not routinely used for this reason.

16. Methods of Prophylaxis
Moderate- and High-Risk Patients
Low-molecular-weight heparin
(LMWH):
Insertion and removal of epidural catheters (used for
perioperative analgesia) have been associated with the
development of epidural haematomas in anticoagulated
patients, with potentially serious neurologic consequences.
Current recommendations:
Delay insertion or removal of an epidural catheter for 12h after a
dose of LMWH.
Delay subsequent doses of LMWH for 2h following catheter
insertion or removal.

17. Methods of Prophylaxis
Moderate- and High-Risk Patients
Anticoagulants:
Warfarin, either in low or full
anticoagulation dose, is effective in
reducing thromboembolism.
However, bleeding complications are
common and accordingly warfarin is not
in regular use for this purpose.

18. Methods of Prophylaxis
Moderate- and High-Risk Patients
Antiplatelet agents:
Aspirin:
An effective antiplatelet agent.
Disadvantages: Ineffective as the sole agent to
prevent DVT.
Dextrans:
Reduce the incidence of postoperative venous
thrombosis.
Disadvantages: Expensive, must be given IV and are
more difficult to administer than SC heparin.
Not used routinely.

19. Methods of Prophylaxis
Moderate- and High-Risk Patients
In some areas of surgery, particularly where
the surgeon wishes to avoid intraoperative
anticoagulation, mechanical compression is
a useful option for the medium- and high-
risk groups

20. Thromboprophylaxis according to Risk Group
Low-risk groups:
Leg elevation
Early mobilization
Moderate-risk groups:
Leg elevation
Early mobilization
Graduated thromboembolic deterrent
(TED) compression stockings
Subcutaneous LMWH once daily.
High-risk groups:
Leg elevation
Early mobilization
TED stockings
Subcutaneous LMWH,
Mechanical calf compression

21. Methods of Prophylaxis
Postoperative Care
Check the limbs daily for early signs of venous
thrombosis (e.g. calf tenderness and leg swelling).
If there is any suggestion of the development of
clinical venous thrombosis, a Doppler ultrasound
and/or venogram is required to diagnose the
peripheral venous thrombosis prior to the
commencement of full anticoagulation.

22. References
Kingsnorth AN, Bowley DM (eds.):
Fundamentals of Surgical Practice, 3rd
Ed. Cambridge
University Press 2011.
Kingsnorth AN, Majid AA (Eds): Fundamentals
of Surgical Practice; 2nd
ed. Cambridge University
Press, 2006.
Kirk RM, Ribbans WJ: Clinical Surgery in
General: RCS Course Manual; 4th
ed. Churchill
Livingstone, 2004.