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Blood Tests Before Surgery: What Do They Mean for Blood Thinner Users?
Published: Jul 04, 2024
If you take blood thinners and are preparing for surgery, you'll likely need some blood tests. But what are doctors looking for, and how do the results affect your care?
INR: The Classic Warfarin Test
For patients on warfarin, the International Normalized Ratio (INR) is crucial. It measures how long it takes your blood to clot. A normal INR is about 1, but warfarin users aim for 2-3. Before surgery, doctors want to see the INR drop below 1.5 to reduce bleeding risk. This usually takes 5-7 days after stopping warfarin.
Tests for Newer Blood Thinners
Medications like apixaban, rivaroxaban, or dabigatran don't affect the INR. Instead, specialized tests measure their levels directly. These aren't always needed but can be helpful in emergencies or for high-risk procedures. For example, an anti-Xa activity test can check rivaroxaban levels.
Other Important Tests
Your doctor may also check your complete blood count to assess anemia risk, and kidney function tests since some blood thinners are cleared by the kidneys. Liver function tests can be important too, especially for certain blood thinners. These results help customize your medication management plan.
When Tests Aren't Needed
Interestingly, routine testing isn't always necessary before surgery with newer blood thinners. Their predictable effects mean simply stopping the medication for a set time is often sufficient. However, testing may still be done in complex cases or emergency situations.
Frequently Asked Questions
Usually once before stopping medication and again before surgery.
Your doctor may delay surgery or use reversal treatments.
It's best to discuss results with your healthcare provider.
Most are, but check with your insurer about specialized tests.
Usually not, but follow your doctor's specific instructions.
Knowledge Is Power
Understanding your blood tests helps you actively participate in safely managing your blood thinners before surgery.
References
- Douketis JD et al. Blood. 2012;120(15):2954-2962.
- Faraoni D et al. Anesth Analg. 2016;123(5):1163-1173.
- Godier A et al. Thromb Haemost. 2017;117(2):233-245.
This article has been reviewed for accuracy by one of the licensed medical doctors working for Doctronic. Always discuss health information with your healthcare provider.
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