Overview
Definition:
Perioperative anticoagulation management involves the strategic use of anticoagulant or antiplatelet medications around surgical procedures to balance the risk of thromboembolic events against the risk of perioperative bleeding
This requires careful consideration of the patient's underlying thrombotic risk, the type and magnitude of surgery, and the properties of the anticoagulants used.
Epidemiology:
Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common complication after surgery, with incidence rates varying significantly based on surgical risk factors, patient comorbidities, and the type of surgery
Estimates suggest VTE occurs in 1-5% of general surgery patients without prophylaxis, and up to 10-20% in high-risk procedures like orthopedic or major abdominal surgery
Bleeding complications also occur frequently, impacting patient outcomes and healthcare costs.
Clinical Significance:
Inadequate perioperative anticoagulation can lead to life-threatening VTE, morbidity, and mortality
Conversely, overly aggressive anticoagulation or inappropriate bridging can result in severe, potentially fatal hemorrhage
For surgical residents preparing for DNB and NEET SS, understanding these nuances is critical for making informed clinical decisions, improving patient safety, and managing surgical outcomes effectively.
Indications For Anticoagulation
Thrombotic Risk Factors:
History of VTE
Inherited or acquired thrombophilias (e.g., Factor V Leiden, Antithrombin deficiency)
Mechanical prosthetic heart valves
Certain arrhythmias (e.g., atrial fibrillation with risk factors for stroke)
Recent myocardial infarction or stroke
Malignancy
Immobility.
Surgical Risk Factors:
Major orthopedic surgery (hip/knee arthroplasty)
Major abdominal or pelvic surgery
Major cancer surgery
Prolonged operative time (>2 hours)
Significant blood loss during surgery
Laparoscopic surgery with extended duration.
Pre Existing Anticoagulation:
Patients already on anticoagulation for conditions like atrial fibrillation, mechanical heart valves, or VTE require careful planning to minimize interruptions and maintain adequate anticoagulation or implement bridging therapy where indicated.
Risk Assessment
Patient Factors:
Age > 40 years
Obesity (BMI > 30)
History of VTE
Presence of malignancy
Reduced mobility
Congestive heart failure
Renal insufficiency
Liver disease
Hormone therapy (estrogen)
Smoking.
Surgical Factors:
Type of surgery (orthopedic, general, gynecologic, oncologic)
Duration of surgery
Estimated blood loss
Use of tourniquets
Minimally invasive vs
open procedures
Postoperative immobility.
Risk Stratification Tools:
Use of validated risk scores (e.g., Caprini score for general surgery, specific scores for orthopedic surgery) to stratify patients into low, moderate, and high risk for VTE
Assessment of bleeding risk based on patient comorbidities and surgical procedure.
Management Strategies
Prophylaxis Without Anticoagulation:
Mechanical prophylaxis (graduated compression stockings, intermittent pneumatic compression devices)
Early mobilization
Hydration.
Pharmacological Prophylaxis:
Low molecular weight heparins (LMWH
e.g., Enoxaparin 40 mg SC once daily for most general surgeries, 30 mg SC twice daily for high-risk orthopedic or general surgery patients)
Unfractionated heparin (UFH
5000 units SC every 8-12 hours)
Direct oral anticoagulants (DOACs
e.g., Rivaroxaban, Apixaban) may be used in select cases, particularly in orthopedic surgery, following specific guidelines
Fondaparinux is an alternative for VTE prophylaxis in certain high-risk patients.
Bridging Therapy:
Temporary discontinuation of oral anticoagulants (e.g., Warfarin, DOACs) and initiation of parenteral anticoagulation (LMWH or UFH) for patients at high risk of VTE during the periprocedural period
This is typically considered for patients with mechanical heart valves, recent VTE, or high thrombotic risk
Bridging is usually stopped shortly before surgery and resumed postoperatively once hemostasis is achieved.
Anticoagulation Discontinuation And Resumption:
Warfarin: Discontinue 5 days before surgery, monitor INR (target <1.5)
DOACs: Discontinue 24-72 hours preoperatively depending on renal function and drug (e.g., Apixaban 24h, Rivaroxaban 48h for normal renal function)
LMWH: Discontinue 12-24 hours preoperatively
UFH: Discontinue 4-6 hours preoperatively
Resumption is typically 24-72 hours postoperatively, guided by surgical hemostasis and patient's risk factors.
Anticoagulant Reversal
Indications For Reversal:
Life-threatening hemorrhage
Emergency surgery with significant bleeding risk
Trauma with active bleeding.
Reversal Agents:
Vitamin K (phytonadione) for Warfarin
Protamine sulfate for unfractionated heparin
Specific reversal agents for DOACs (e.g., Idarucizumab for Dabigatran, Andexanet alfa for Rivaroxaban and Apixaban)
Fresh frozen plasma (FFP) and prothrombin complex concentrates (PCCs) can be used for broader reversal, especially when specific agents are unavailable or inadequate.
Management Of Bleeding:
Immediate cessation of anticoagulants
Hemostatic measures (pressure, surgical intervention)
Transfusion of blood products
Administration of appropriate reversal agents based on the anticoagulant used and clinical scenario
Close monitoring of vital signs and laboratory parameters (INR, aPTT, platelet count, fibrinogen).
Specific Surgical Considerations
Neurosurgery:
High risk of bleeding
Anticoagulation often held for extended periods
bridging therapy is controversial and case-dependent
Prophylaxis typically mechanical
Strict hemostasis is paramount.
Cardiac Surgery:
Patients with mechanical heart valves require careful bridging protocols
Anticoagulation management is highly specialized and depends on valve type, position, and patient risk
Postoperative anticoagulation is resumed as per specific cardiac surgery guidelines.
Orthopedic Surgery:
High risk of VTE
Prophylaxis is standard, often with LMWH or DOACs
Bridging therapy may be considered for high-risk patients with mechanical valves or prior VTE
Early ambulation and mechanical prophylaxis are crucial.
Gastrointestinal Surgery:
Risk of bleeding and VTE
Prophylaxis is usually initiated postoperatively
Bridging may be necessary for patients on chronic anticoagulation with high thrombotic risk
Management depends on the extent of surgery and patient's risk profile.
Key Points
Exam Focus:
Understanding the balance between VTE prophylaxis and bleeding risk
Knowing the appropriate anticoagulants for prophylaxis and their doses
Recognizing indications and contraindications for bridging therapy
Familiarity with reversal agents and their indications
Differentiating management strategies for different surgical specialties.
Clinical Pearls:
Always assess individual patient risk for both VTE and bleeding
Tailor anticoagulation strategies to the specific surgical procedure and patient's comorbidities
Communicate clearly with the surgical and anesthesia teams
Reassess anticoagulation needs daily in the postoperative period
Do not hesitate to consult hematology for complex cases.
Common Mistakes:
Over-anticoagulation leading to hemorrhage
Under-anticoagulation leading to VTE
Inappropriate bridging therapy in low-risk patients
Delayed resumption of anticoagulation postoperatively
Failure to consider mechanical prophylaxis
Inadequate reversal of anticoagulation in bleeding emergencies.