Do I need to obtain a PT/INR before a bone marrow biopsy in an otherwise healthy adult with a normal platelet count and no history of liver disease, recent surgery, or anticoagulant use?

PT/INR Testing Before Bone Marrow Biopsy

In an otherwise healthy adult with a normal platelet count and no history of liver disease, recent surgery, or anticoagulant use, routine PT/INR testing before bone marrow biopsy is not necessary.

Risk Stratification for Bone Marrow Biopsy

Bone marrow biopsy is classified as a low to moderate bleeding risk procedure, with significant hemorrhage occurring in only 0.007-1.1% of cases 1. This is substantially lower than the bleeding risk associated with percutaneous lung or liver biopsies, where routine coagulation testing is recommended 2.

When PT/INR Testing Is NOT Required

For low-risk patients, routine coagulation screening is unnecessary 1. This includes patients who:

• Have no clinical history suggesting coagulopathy 1
• Are not taking anticoagulants or antiplatelet agents 1, 3
• Have no liver disease 2
• Have no renal impairment 2
• Have normal platelet counts 3
• Have no history of abnormal procedure-related bleeding 2

The evidence shows that preoperative screening for coagulopathies not suspected on clinical grounds is unnecessary for procedures where direct visualization is possible 2. While bone marrow biopsy lacks direct visualization, its extremely low bleeding rate supports a selective rather than universal testing approach 1.

When PT/INR Testing IS Required

Obtain PT/INR in the following clinical scenarios:

• Active anticoagulation: Patients on warfarin or who recently stopped warfarin (within 5 days) 2, 4
• Liver disease: Any degree of hepatic dysfunction, as PT/INR may be elevated and reflects synthetic function 2
• Clinical suspicion of coagulopathy: History of easy bruising, mucosal bleeding, or family history of bleeding disorders 2
• Malnutrition or vitamin K deficiency: Patients in intensive care, on prolonged antibiotics, or with cholestatic disease 2
• Acute kidney injury: Associated with platelet dysfunction and increased bleeding risk 2

Key Thresholds and Management

Platelet Count Considerations

Platelet count is more clinically relevant than PT/INR for bone marrow biopsy bleeding risk 3. The evidence shows:

• Bleeding complications correlate with low platelet counts (p = 0.002), not with abnormal coagulation profiles 3
• CT-guided bone marrow biopsy is safe with platelet counts of 20,000-50,000/μL, with hemorrhagic complication rates below 1.6% 5
• Routine platelet transfusion may not be necessary for counts of 20,000-50,000/μL 5

Anticoagulation Management

If PT/INR testing reveals abnormalities or the patient is anticoagulated:

• Warfarin: Stop 5 days before the procedure; INR should be ≤1.4 for non-lesional biopsies 2
• Direct oral anticoagulants: Stop 2 days prior (longer for dabigatran with renal impairment) 2, 4
• Heparin/LMWH: Discontinue 12-24 hours before biopsy 4
• Aspirin: Stop 3 days prior when time allows 2, 4
• P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor): Stop 7-10 days before 2, 4

Common Pitfalls to Avoid

Do not reflexively order PT/INR based solely on the procedure type. Unlike percutaneous lung or liver biopsies where routine coagulation testing is recommended due to higher bleeding rates 2, bone marrow biopsy has a much lower hemorrhagic risk profile 1.

Do not assume PT/INR predicts bleeding risk in all contexts. In liver disease, 90% of bleeding after liver biopsy occurred in patients with INR <1.3, demonstrating that normal PT/INR provides no guarantee against bleeding 2. Similarly, coagulation profiling appears irrelevant for bone marrow biopsy bleeding risk 3.

Do not overlook special populations:

• Patients with myeloproliferative neoplasms can develop acquired von Willebrand syndrome, increasing bleeding risk and requiring extra vigilance 1, 6
• Obesity, thrombocytosis, and hyperleukocytosis are associated with retroperitoneal hemorrhage after bone marrow biopsy 6

Clinical Decision Algorithm

1. Obtain focused history: Anticoagulant use, liver disease, renal disease, bleeding history, recent vitamin K intake 2, 1
2. Check platelet count: This is the most relevant laboratory test 3, 5
3. Order PT/INR only if: History reveals risk factors listed above (anticoagulation, liver disease, clinical coagulopathy suspicion) 1
4. Proceed without PT/INR: If history is negative and platelet count is adequate 1, 3