VTE Risk in Surgical Patients

Multiple risk factors can increase patient risk of VTE

Surgery, especially major orthopaedic surgery involving the lower extremity and major surgery for cancer, is a prominent risk factor for the development of venous thromboembolism (VTE).³ And if a patient has many risk factors, there is generally a cumulative impact on VTE risk.^{3, 55, 56}

Perioperative, exposing factors affecting risk include:

Dehydration
Postoperative immobilisation
Need for transfusion

Patient-related, or predisposing, risk factors include:

Inherited thrombophilia
Advanced age
Obesity
Cancer
Prior VTE
Varicose veins
Use of oestrogen-containing medications (such as oral contraceptives and hormone replacement therapy)

The benefits of preventive measures to lower VTE risk

The chance of developing VTE during or after a surgical procedure varies with the nature of the procedure, including its duration, and with perioperative care.³

Underuse of prophylaxis

For more than 20 years, routine preventive anticoagulant therapy has been the standard of care for major orthopaedic surgery. Despite the well-recognised risks of VTE in hospitalised patients, there remains a low rate of appropriate prophylaxis. A recent multinational, cross-sectional audit⁵⁷ including 32 countries — the ENDORSE (Epidemiologic International Day for the Evaluation of Patients at Risk for Venous Thromboembolism in the Acute Hospital Care Setting) survey — revealed that 93% of patients who had major surgery were at risk for VTE but that only 62% received standard VTE prophylaxis.²⁰⁹ These findings, emerging after years of attention to the well-recognised problem of VTE, suggest a need for hospital-wide strategies to ensure appropriate preventive care for all patients at risk.

A comprehensive body of research has established that pharmacologic measures to prevent VTE in appropriate surgical patients are both effective and associated with a low risk of postoperative bleeding complications. Therefore, the risk/benefit ratio favours the prophylactic approach to treatment. In addition, this approach has proven to be cost-effective in moderate- and high-risk general surgery patients.⁵⁵

VTE risk in orthopaedic surgery

Major orthopaedic surgery involving the lower extremity — hip or knee replacement surgery or hip fracture surgery — is associated with a high risk of VTE. The risk results from stasis of venous blood flow as well as direct injury to the veins during surgery.²⁶ In patients at risk, without prophylaxis, rates of deep vein thrombosis (DVT) 7 to 14 days after major orthopaedic surgery range from 40% to 60% when assessed by venography. Findings from a prespecified subanalysis of data from the ENDORSE survey indicate that VTE prophylaxis remains underutilised in all major types of surgery.²⁰⁹ Data from this survey indicated that globally 1 in 7 patients considered at risk for VTE did not receive appropriate preventive treatment to decrease that risk. The percentage of patients who did receive appropriate prophylaxis varied widely between countries, eg, 27% in India, 68% in Brazil, 78% in the UK, 87% in the US, and 96% in Germany.²⁰⁹

A recent publication has confirmed that the risk of venous thromboembolism is high after total hip arthroplasty and persists after hospital discharge. The RECORD2 trial compared the use of rivaroxaban for extended thromboprophylaxis (5 weeks) with short-term thromboprophylaxis (2 weeks) with enoxaparin. The results provided firm evidence that extended thromboprophylaxis with rivaroxaban substantially reduced the burden of venous thromboembolism, including major and symptomatic events. This has been achieved without increasing the bleeding risk.¹⁵² Therefore, pharmacological prophylaxis for up to 35 days is recommended for patients undergoing total, hip arthroplasty.³

Progression of DVT

Studies of the natural history of DVT after orthopaedic surgery have shown that, in many patients, venous thrombosis causes no symptoms. But, because of ongoing venous stasis during the recovery period, some thrombi can expand. These thrombi may break free to cause a pulmonary embolism (PE), often after the patient leaves the hospital.³ Patients who have had total hip replacement and no VTE by venogram at discharge continue to be at risk of late-onset VTE up to 35 days after surgery.⁵⁹ Current recommendations regarding the duration of anticoagulation treatment following hip and knee surgery are based on this understanding of the chronology of VTE.³

VTE risk in general and emergency surgery

The risk of DVT in patients undergoing major abdominal surgery without thromboprophylaxis is 15% to 30%; the risk of fatal PE in this same group is approximately 0.08%. ⁵⁵ Data from the multinational ENDORSE survey revealed that in patients undergoing elective surgery 93% were at risk for VTE based on American College of Chest Physicians guidelines but that only 62% received VTE prophylaxis consistent with these guidelines.²⁰⁹
Duration and type of surgery affect thrombosis risk, as do increasing age and other traditional risk factors like cancer, prior VTE, and obesity.⁵⁵

ENDORSE survey findings also revealed that among patients undergoing emergency surgery, 90% were at risk for VTE while only 58% received any recommended VTE prophylaxis.²⁰⁹

VTE risk in laparoscopic surgery

The relative risk of VTE with laparoscopy versus open procedures has not yet been investigated in depth. Based on the pathophysiology of VTE, factors that may heighten the risk with laparoscopy are duration of the procedure, patient positioning (eg, reverse Trendelenberg position for some procedures), and the injection of air into the peritoneum. Conversely, shorter hospital stays and more rapid postoperative mobilisation would be expected to decrease the risk.⁵⁵

VTE risk in major gynaecologic, major open urologic, and neurologic surgery

Major gynaecologic surgery poses a VTE risk that is comparable to the risk involved in general abdominal surgery (15% to 30% without preventive therapy). Major open urologic procedures confer significant risk, but transurethral procedures do not.^{3, 60} Venographic studies in patients undergoing neurosurgery show a rate of DVT of approximately 30%. The risks are increased in cranial surgery compared to spinal surgery, in cases of malignant tumours compared to cases of benign tumours, and in patients with leg weakness.⁵⁶ The ENDORSE survey found that compared to patients having general or orthopaedic surgery those undergoing urologic/gynaecologic or other procedures were less likely to receive appropriate VTE prophylaxis. Approximately half of these patients received no prophylaxis despite being considered at risk for VTE.²⁰⁹

VTE risk in cancer surgery

Cancer confers an increased risk of VTE. Accordingly, it is not surprising that the frequency of VTE in patients undergoing cancer surgery is roughly twice that seen in patients without malignancies who have comparable operations.⁵⁵

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Article references

3 - 1. Geerts WH, Bergqvist D, Pineo GF, et al. Prevention of venous thromboembolism: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest. 2008;133(6)(suppl):381S-453S.
55 - Kakkar AK. Prevention of venous thromboembolism in general surgery.In: Colman RW, Marder VJ, Clowes AW, George JN, Goldhaber SZ, eds. Hemostasis and Thrombosis: Basic Principles and Clinical Practice. 5th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2006:1361-1367.
56 - Motte S, Samama CM, Guay J, Barré J, Borg JY, Rosencher N. Prevention of postoperative venous thromboembolism. Risk assessment and methods of prophylaxis. Can J Anaesth. 2006;53(6)(suppl):S68-S79.
57 - Cohen AT, Tapson VF, Bergmann JF, et al; ENDORSE Investigators. Venous thromboembolism risk and prophylaxis in the acute hospital care setting (ENDORSE study): a multinational cross-sectional study. Lancet. 2008;371(9610):387-394.
209 - Kakkar AK, Cohen AT, Tapson VF, et al; ENDORSE Investigators. Venous thromboembolism risk and prophylaxis in the acute care hospital setting (ENDORSE survey): findings in surgical patients. Ann Surg. 2010;251(2):330-338.
26 - Merli GJ. Pathophysiology of venous thrombosis, thrombophilia, and the diagnosis of deep vein thrombosis-pulmonary embolism in the elderly. Clin Geriatr Med. 2006;22(1):75-92, viii-ix.
152 - Kakkar AK, Brenner B, Dahl OE, et al; RECORD2 Investigators. Extended duration rivaroxaban versus short-term enoxaparin for the prevention of venous thromboembolism after total hip arthroplasty: a double-blind, randomised controlled trial. Lancet2008;372(9632):31-39.
59 - Planes A, Vochelle N, Darmon JY, Fagola M, Bellaud M, Huet Y. Risk of deep-venous thrombosis after hospital discharge in patients having undergone total hip replacement: double-blind randomised comparison of enoxaparin versus placebo. Lancet. 1996;348(9022):224-228.
60 - Nicolaides AN, Fareed J, Kakkar AK, et al. Prevention and treatment of venous thromboembolism. International Consensus Statement (guidelines according to scientific evidence). Int Angiol. 2006;25(2):101-161.

Venous thromboembolism: A condition in which a blood clot (thrombus) forms in a vein, which in some cases then breaks free and enters the circulation as an embolus, finally lodging in and completely obstructing a blood vessel, e.g., in lungs causing a PE. The term encompasses both DVT and PE.
Prophylaxis: The prevention of a disease or pathological condition.
Venography: An X-ray of the veins performed by first injecting a radiopaque contrast (shows up on X-ray) into the vein in question and then taking a conventional X-ray. Used to demonstrate blockage of a vein. Commonly used in the lower extremities to diagnose DVT.
Enoxaparin: A low-molecular-weight heparin currently regarded as the standard of care for VTE prevention in orthopaedic surgery. Enoxaparin is administered by subcutaneous injection and is associated with a low risk of heparin-induced thrombocytopaenia.
Rivaroxaban: Oral, direct Factor Xa inhibitor.
Thromboprophylaxis: The use of medication or medical devices to prevent the formation of blood clots.
Venous stasis: The presence of an abnormally low rate of blood flow in the veins. This can be caused by, for example, the use of a tourniquet or prolonged immobility.
American College of Chest Physicians: Multidisciplinary international medical society based in Northbrook, Illinois, USA, that focuses on the treatment and prevention of all diseases of the chest. It has over 16,000 active members with physicians representing all chest medicine disciplines. Publishes the journal Chest.
Reverse Trendelenberg: A person in the 'Reverse Trendelenberg' position is lying on the back with their feet slightly lower than their head.