Subinternship Surgery · Year 4 · from Subinternship Surgery
Case 2: Managing Anticoagulation for Urgent Cholecystectomy
Patient Presentation
Demographics: 72-year-old female
Chief Complaint: Right upper quadrant pain for 24 hours
History of Present Illness: Mrs. Chen presents to the ED with RUQ pain, nausea, and low-grade fever. Ultrasound shows cholelithiasis with gallbladder wall thickening (6mm), pericholecystic fluid, and positive sonographic Murphy's sign consistent with acute cholecystitis. She is hemodynamically stable and admitted for IV antibiotics with plan for cholecystectomy within 24-48 hours.
Past Medical History:
- Atrial fibrillation (persistent) on warfarin
- Mechanical mitral valve replacement 8 years ago
- Hypertension
- CHA2DS2-VASc score: 5 (female, age, HTN, vascular disease)
- Current INR: 2.8
Medications:
- Warfarin 5mg daily
- Metoprolol 50mg BID
- Lisinopril 10mg daily
Physical Examination:
- Vitals: T 38.2C, HR 88 irregular, BP 145/82
- Abdomen: RUQ tenderness with guarding, positive Murphy's sign
- No peritoneal signs
Clinical Questions
- What is this patient's thromboembolic risk, and does she require bridging anticoagulation?
Thromboembolic Risk Assessment:
- Mechanical mitral valve = HIGH RISK (highest risk valve position)
- Atrial fibrillation with CHA2DS2-VASc of 5 = HIGH RISK
Decision: BRIDGING IS REQUIRED
- Mechanical mitral valve carries the highest thromboembolic risk
- Stopping anticoagulation without bridging is not acceptable
- Annual stroke risk without anticoagulation: >10%
- Outline a bridging protocol for this patient:
Preoperative Bridging Timeline: | Day | Action | |-----|--------| | Day -5 | Stop warfarin | | Day -3 | Start enoxaparin 1mg/kg BID (therapeutic dose) when INR <2.0 | | Day -1 | Check INR (goal <1.5 for surgery) | | Day -1 evening | Hold evening dose of enoxaparin | | Day 0 (surgery) | Check INR, proceed if <1.5 |
Postoperative Bridging:
- Resume enoxaparin 12-24 hours postop if hemostasis secure (assess bleeding risk)
- Restart warfarin POD 1 (takes 5 days to achieve therapeutic INR)
- Continue bridging until INR therapeutic (2.5-3.5 for mechanical mitral valve)
- Consider reduced-dose bridging (0.5mg/kg BID) if high surgical bleeding risk
- The patient's surgery is moved up due to worsening symptoms. INR is still 2.1 the morning of surgery. What are your options?
Reversal Options:
- Vitamin K 2.5-5mg PO/IV: Takes 6-12 hours for effect; suitable if surgery can wait
- Fresh Frozen Plasma (FFP): Immediate effect but requires volume administration; gives 4-6 hours of coverage
- 4-Factor PCC (Prothrombin Complex Concentrate): Rapid, complete reversal; preferred for urgent surgery
Recommendation: Given mechanical valve, avoid full reversal if possible. If surgery can wait 6-12 hours, give low-dose Vitamin K (2.5mg IV). If must proceed immediately, give 4F-PCC and accept small residual INR elevation (target 1.5).
- What antibiotics should be given preoperatively?
Antibiotic Selection:
- Already receiving treatment antibiotics for cholecystitis
- Standard prophylaxis: Cefazolin 2g IV within 60 minutes of incision
- Given ongoing infection: Continue current regimen (e.g., piperacillin-tazobactam) and ensure dose given within 60 minutes of incision
- Redose cefazolin for cases >4 hours or blood loss >1.5L
Clinical Image
Image: Ultrasound image demonstrating cholelithiasis (gallstones) with characteristic acoustic shadowing. Source: Wikimedia Commons. License: CC BY-SA 3.0.
Image Attribution: Ultrasound of cholelithiasis. Hellerhoff, Wikimedia Commons. CC BY-SA 3.0.