What to avoid prior to surgery and lab tests
November 1, 2019
I recently wrote about some impressive tests that you can self-order, thus taking the headache out of getting lab tests. But what about the important instructions that come with some lab tests, and what are the best instructions to follow if you have a surgery scheduled.
The most common inquiry is this: Do I really need to stop all my medications before this test?
This question isn't easy to answer because some medications are needed for comfort and well-being. For example, what if you are reliant on your morning pill for acid reflux? You can safely stop it abruptly, but, if you don't take it, you will be very uncomfortable. Another example is with analgesics like tramadol, oxycodone and morphine. You can't just suddenly stop those or
you'll slip into withdrawal pretty quickly. Ask if you're allowed to take those two the morning
of your procedure.
You also cannot suddenly stop an anti-depressant or anti-epileptic drug. These and many other medications require slow tapering to get off. If you suddenly discontinue certain drugs, then you could encounter dangerous withdrawal symptoms, even seizures. I can see why this question comes up a lot for patients. Ask well before your surgery so you don't have to reschedule due to this type of oversight.
Blood thinners are the most dangerous ones to remain on if you're having surgery, or some procedure that requires an IV drip or a blood draw, like a colonoscopy for example. You do not want your blood to be super thin when you go in for these procedures or the bleeding could become profuse or internalized. So for sure, you do not want to be on blood thinning drugs for at least three days prior to some tests: Anticoagulants, Warfarin (Coumadin), Enoxaparin, Clopidogrel, Ticlopidine, aspirin, ibuprofen and other NSAIDs, Dipyridamole .
Another category of medications that people don't usually warn about, but I feel should be included in this conversation are those drugs that slow down your heart rate. My reasoning is that anesthesia also slows down your heart rate and the combo could lead to severe bradycardia. I'm referring to "beta" and "calcium" channel blockers.
Another important question is, "Should I really stop eating and drinking before a test?"
The blanket answer is yes! If the facility or hospital puts that request on your instruction sheet, you should follow it. Eating and drinking too close to surgery could force a reschedule of the surgery. The worry is aspiration.
As for other tests, it becomes less clear. For example, if you are scheduled to have a pelvic ultrasound to see your cervix or ovaries, I'm not sure why food would be a problem. And likewise, I do not understand the need for "no food or drink" if you're having a thyroid blood test. You probably should eat before that type of test, the results will be more realistic.
There are certain things that you should not take or eat before a urine test. The list is very long but generally speaking avoid beets, coffee, caffeinated tea and B vitamins.