Perioperative VTE Prophylaxis — SAQ

Stem

A 68-year-old woman with a BMI of 34 is admitted for elective total hip replacement. She has a history of a DVT 5 years ago. She takes aspirin but no other medications.

Questions

a) What is this patient's VTE risk category? (2 marks)

HIGH RISK (ACCP 9th ed). Caprini five-point item: elective arthroplasty; plus previous VTE (3 points), age 61–74 (2 points), BMI above 25 (1 point). ACCP estimated baseline VTE risk at Caprini 5 or more is about 6 percent. She needs pharmacologic prophylaxis plus an intermittent pneumatic compression device in hospital.

b) State Virchow's triad and explain how surgery contributes to each component. (3 marks)

1. STASIS: anaesthesia and postoperative immobility abolish the calf-muscle pump.
2. HYPERCOAGULABILITY: surgical tissue-factor release, thrombin generation, platelet activation.
3. ENDOTHELIAL INJURY: operative trauma to veins and tissues.

c) Describe the recommended VTE prophylaxis for this patient. (3 marks)

1. Pharmacological: ACCP accepts LMWH (preferred), fondaparinux, dabigatran, apixaban, rivaroxaban, low-dose UFH, adjusted-dose VKA, aspirin or an IPCD for a minimum of 10 to 14 days, and suggests extending up to 35 days. Trial regimens after hip replacement: enoxaparin 40 mg SC once daily (started 12 h before surgery) or apixaban 2.5 mg twice daily (started 12 to 24 h after wound closure) for 35 days; dabigatran 220 mg once daily (half-dose 1 to 4 h post-op) for 28 to 35 days.
2. Mechanical: add an IPCD during the hospital stay (ACCP Grade 2C).
3. Early mobilisation.

d) What is post-thrombotic syndrome? (2 marks)

Chronic venous hypertension after DVT from valve damage and residual obstruction (swelling, pain, pigmentation, lipodermatosclerosis, venous ulcers). CHEST 2016 suggests not using compression stockings routinely to prevent it (Grade 2B).