Blood Thinners Before a Colonoscopy or Endoscopy

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Blood thinners before colonoscopy or upper endoscopy are one of the most common questions people ask when they schedule a procedure, and one of the few where the right answer is different for almost everyone. Some people keep taking their medication straight through the exam. Others pause it briefly. A few are asked to postpone the procedure altogether. This page is for adults in Arlington, Annandale, and the rest of Northern Virginia who take warfarin, a newer anticoagulant such as apixaban or rivaroxaban, clopidogrel, or daily aspirin and have a colonoscopy or endoscopy coming up. It explains what the professional guidelines weigh and why the decision is shared between your gastroenterologist and the physician who prescribes the medication. It is not a schedule to follow.

This article is general education, not medical advice. Do not stop, skip, or change any blood thinner on your own. For some people, stopping one can lead to a stroke, a heart attack, or a blood clot. The written instructions you receive from the office performing your procedure are the ones that apply to you.

What counts as a blood thinner before a colonoscopy

"Blood thinner" is an everyday name for two different groups of medicines, and the guidelines treat them differently. The 2022 clinical practice guideline from the American College of Gastroenterology (ACG) and the Canadian Association of Gastroenterology (CAG) on anticoagulants and antiplatelet drugs around endoscopy groups them this way:

• Anticoagulants slow the clotting process itself. They include warfarin (Coumadin) and the direct oral anticoagulants, often called DOACs: apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa), and edoxaban (Savaysa). They are commonly prescribed for atrial fibrillation, after a blood clot in the leg or lung, and for some heart valve conditions.
• Antiplatelet drugs keep platelets from sticking together. They include aspirin and a group called P2Y12 inhibitors: clopidogrel (Plavix), prasugrel (Effient), and ticagrelor (Brilinta). They are commonly prescribed after a heart attack, a coronary stent, or a stroke. Some people take aspirin together with a P2Y12 inhibitor, which is called dual antiplatelet therapy.

The American Society for Gastrointestinal Endoscopy (ASGE) guideline on antithrombotic agents for GI endoscopy also names injectable anticoagulants such as heparin and enoxaparin. Over-the-counter pain relievers such as ibuprofen and naproxen, and supplements, belong on the list you give the office too, even though most people do not think of them as blood thinners.

Why blood thinners before colonoscopy need a plan

Every decision about a blood thinner around a procedure balances two risks that pull in opposite directions.

• The risk of bleeding. Blood thinners make bleeding more likely after a biopsy or a polyp removal, and harder to stop if it happens. The ACG and CAG guideline notes that these drugs raise the risk of GI bleeding both from conditions such as ulcers and diverticula and after endoscopic procedures.
• The risk of a clot. The medication is there to prevent something serious: a stroke in atrial fibrillation, a clot in a coronary stent, a new clot in the leg or lung. The ASGE guideline estimates the absolute risk of an embolic event when anticoagulation is interrupted for 4 to 7 days at about 1 percent, and the risk varies with the condition the medication treats.

Which risk matters more depends on two things: how likely the planned procedure is to cause bleeding, and how likely a pause is to cause a clot in you specifically. Neither can be judged from a medication name alone. The ACG and CAG panel also reviewed research on what patients value and found real variation: people generally placed more weight on preventing a stroke than on avoiding GI bleeding, unless they had already had a GI bleed. The guideline lists patient preference as part of the decision.

How procedure type changes the plan for blood thinners before colonoscopy or EGD

Not every endoscopy carries the same bleeding risk. Both guidelines start by sorting procedures into lower and higher risk.

Lower-risk procedures

The ASGE guideline lists diagnostic upper endoscopy, colonoscopy, and flexible sigmoidoscopy, including mucosal biopsy, as low-risk procedures, along with capsule endoscopy. The ACG and CAG panel agreed that the risk of clinically significant bleeding with diagnostic endoscopy and standard biopsies is very low. If your upper endoscopy is diagnostic, the bleeding side of the balance is usually small.

Polyp removal and other higher-risk procedures

Removing a polyp raises the bleeding risk above a biopsy. The ASGE guideline classifies polypectomy as a higher-risk procedure and gives a post-polypectomy bleeding range of 0.3 to 10 percent, depending on the polyp's size, location, and shape, and on whether it is removed with or without electrical current (cautery). The newer ACG and CAG guideline takes a somewhat different view. It notes that most polyps under 10 millimeters are now removed with a cold snare, without cautery, and the panel considered the bleeding risk very low for most polypectomies. It reserves the highest-risk category for large or complex polyp removal and for advanced procedures such as endoscopic mucosal resection, endoscopic submucosal dissection, and sphincterotomy during ERCP.

This is why blood thinners before colonoscopy raise a question that a diagnostic upper endoscopy often does not. Whether a polyp will be found, and how large it is, is usually not known until the exam is under way. Your physician plans for what the colonoscopy is likely to involve, which depends on why it is being done and what earlier exams found. Our guide to colon polyps explains why polyps are removed when they are found.

Some upper endoscopy procedures sit in the higher-risk group as well. The ASGE guideline notes that the safety of esophageal dilation while on anticoagulants is unknown and calls for caution, because a bleed could be in a hard-to-reach place. If your EGD might include stretching a narrowing, that changes the plan. Hemorrhoid banding has its own guidance on blood thinners, covered on that page.

What the guidelines say about warfarin

For people on warfarin having an elective procedure, the 2022 ACG and CAG guideline suggests continuing warfarin rather than interrupting it. That is a conditional recommendation based on very low certainty evidence. When the five available studies of uninterrupted warfarin were pooled, there were no bleeding events in 239 patients, but the panel noted the true risk could be anywhere from 0 to 12.5 percent, and that almost no data exist for advanced procedures. For procedures with a higher bleeding risk, the guideline's discussion describes a temporary interruption as appropriate.

The bigger change concerns bridging, which means giving a short-acting injected anticoagulant while warfarin is paused. The ACG and CAG guideline suggests against bridging for people who pause warfarin for an elective GI procedure, unless they have a mechanical heart valve. Its evidence includes the BRIDGE trial, in which skipping bridging was as effective as bridging at preventing arterial clots (0.4 percent compared with 0.3 percent) and cut major bleeding from 3.2 percent to 1.3 percent. The panel said bridging may still be appropriate for a small group at very high clotting risk, such as people with mechanical valves or a prior clot during a warfarin pause, and that a cardiologist and hematologist should be consulted for them.

The 2016 ASGE guideline suggested bridging for people at high clotting risk having higher-risk procedures. If you were bridged for an earlier procedure, do not assume the same plan applies now.

What the guidelines say about DOACs

Apixaban, rivaroxaban, dabigatran, and edoxaban act quickly and wear off quickly, which shapes how they are handled. For elective endoscopic procedures, the ACG and CAG guideline suggests a temporary interruption of a DOAC rather than continuing it. That is also a conditional recommendation with very low certainty evidence. The panel reasoned that because these drugs wear off within a short time, the clotting risk of a brief pause is expected to be lower than with warfarin.

The most useful data came from the PAUSE study, in which DOACs were stopped and restarted on a standardized plan. In the more than 550 endoscopic procedures in that study, most of them colonoscopies and upper endoscopies with or without biopsy or polyp removal, GI bleeding occurred in 2.5 percent of patients and clots in 0.7 percent over 30 days. The ASGE guideline notes that how long to pause depends on the specific drug and, for some of them, on kidney function, which is one reason the instruction has to come from your care team and not from a general article.

Here, too, the guidelines have moved. The 2016 ASGE guideline suggested continuing DOACs for low-risk procedures. A friend's instructions, or your own from a few years ago, may not match what you are told today.

What the guidelines say about aspirin

The answer for aspirin depends on why you take it.

• Aspirin for secondary prevention, meaning after a heart attack, a stent, a stroke, or a diagnosis of vascular disease. The ACG and CAG guideline suggests against interrupting it for elective endoscopy in general, given its known benefit. The ASGE guideline also states that cardiac aspirin should not be discontinued in most cases. For the highest-risk procedures, such as removal of large or complex polyps, the ACG and CAG panel said a pause could be considered, weighing cardiovascular risk and patient preference.
• Aspirin for primary prevention, meaning taken by someone who has never had a heart attack or stroke. The ACG and CAG guideline states that its recommendations do not apply to this group, and that these patients should stop aspirin before higher-risk endoscopic procedures because the bleeding risk outweighs the small cardiovascular benefit. That still means telling the office and following its instructions, not deciding alone.

If you are not sure which group you belong to, the physician who started the aspirin can tell you. It is one of the most useful things to find out before your procedure is scheduled.

What the guidelines say about clopidogrel and other P2Y12 inhibitors

For people on dual antiplatelet therapy for secondary prevention, the ACG and CAG guideline suggests a temporary interruption of the P2Y12 inhibitor (clopidogrel, prasugrel, or ticagrelor) while continuing aspirin for elective procedures. For people on a P2Y12 inhibitor alone, the panel could not make a recommendation for or against pausing it, because the evidence was too limited and contradictory. The ASGE guideline suggests continuing these drugs for low-risk procedures and pausing them, or switching to aspirin, before high-risk ones.

Recent stents change everything. Stopping antiplatelet therapy too soon after a coronary stent can cause the stent to clot, which is a medical emergency. The ASGE guideline advises against stopping all antiplatelet therapy after a stent is placed and recommends deferring elective procedures after a recent stent, and both guidelines call for the cardiologist or prescribing physician to be involved in high-risk cases. This is the clearest case where your gastroenterologist will not make the decision alone.

When taking blood thinners before colonoscopy means the procedure should wait

For some people, the safest plan is to postpone a scheduled procedure until the period of highest clotting risk has passed. The ACG and CAG guideline excludes these patients from its elective recommendations and says their elective procedures should be deferred. It lists:

• Within 3 months of a blood clot in the leg or lung, a stroke, or a transient ischemic attack.
• Within 3 months of a heart attack or other acute coronary syndrome.
• Within 6 months of a drug-eluting coronary stent, or 1 month of a bare-metal stent, in people without a recent acute coronary syndrome.
• After an acute coronary syndrome, within 12 months of a drug-eluting stent or 2 months of a bare-metal stent.

The ASGE guideline similarly recommends deferring elective procedures until a short course of anticoagulation, such as warfarin after a leg clot, is finished. A routine screening colonoscopy is elective. A colonoscopy or endoscopy for bleeding, anemia, or a concerning finding may not be, and your physicians weigh that difference. Our guide to colon cancer screening options covers the screening decision itself.

Restarting blood thinners after colonoscopy or endoscopy

When to restart a paused medication is a separate decision made at the end of the procedure, based on what was done. The 2022 ACG and CAG guideline could not recommend same-day restart over restarting 1 to 7 days later for warfarin, DOACs, or P2Y12 inhibitors, because no studies compared them. It says the decision should consider whether bleeding was fully controlled during the procedure, the bleeding risk of what was done, your clotting risk, and your preferences. Our guide to recovery after a colonoscopy covers restarting medications and the signs of bleeding that need a call. If you leave without a restart date, call the office rather than guessing.

Blood thinners during a GI bleed are a different situation

Everything above concerns planned procedures. If you take a blood thinner and notice black or tarry stools, vomit blood, or pass more than a small amount of blood from the rectum, that is not a scheduling question. Get evaluated promptly, and do not stop a prescribed blood thinner on your own while you wait. Our guides to black stools and upper GI bleeding and blood in the stool explain which symptoms are urgent.

How to prepare: blood thinners before colonoscopy, step by step

The plan works only if your care team has complete information early enough to coordinate. The ASGE guideline says decisions about pausing these medications should be individualized and discussed before the procedure with the patient and, ideally, the prescribing physician, whether that is a cardiologist, neurologist, hematologist, or primary care physician. Before your colonoscopy or endoscopy:

• Tell the office when you schedule, not the week of the procedure. A pause, if one is needed, and any coordination with another physician take time.
• Bring a complete medication list with the name and dose of every blood thinner, aspirin, over-the-counter pain reliever, and supplement you take.
• Know why you take each one: atrial fibrillation, a past clot, a heart valve, a stent, a stroke, or prevention.
• Note recent events and their dates: a stent, a heart attack, a stroke, a clot, or any recent bleeding.
• Give the name of each prescribing physician so the teams can talk to each other.
• Get instructions in writing, including whether to continue, when to take the last dose if a pause is planned, and when to restart.

Our colonoscopy prep guide covers the rest of the preparation, and if you also take a GLP-1 medication, our guide to GLP-1 medications and endoscopy covers that separate question.

Questions to ask about blood thinners before colonoscopy

• Should I keep taking this medication, or pause it? If I pause it, what is the date and time of my last dose?
• Has my prescribing physician agreed with the plan, or should I call them?
• Do I need any other medication while this one is paused?
• What happens to the plan if a polyp is found?
• When do I restart, and who will tell me?

Planning a procedure around blood thinners in Northern Virginia with GC of NoVA

Gastroenterology Center of Northern Virginia performs colonoscopy and upper endoscopy for adults across Arlington, Annandale, and the surrounding communities, many of whom take an anticoagulant or antiplatelet medication. When you schedule, our physicians review your medication list, the reason for each blood thinner, and what the procedure is likely to involve, and give you written instructions that fit your situation. When a pause is being considered, we work with the cardiologist, neurologist, hematologist, or primary care physician who prescribes the medication. We see patients at our Arlington office, next to VHC Health, and our Annandale office, in the Woodburn Medical complex.

If this is your first visit, our guide to your first gastroenterologist visit explains what to bring, and a complete medication list is the most useful item. To schedule, contact our Arlington office at (703) 522-7476 or our Annandale office at (703) 560-6106, or learn more at gcofnova.com.

This article is for general education and is not medical advice. Talk with a qualified gastroenterologist about your symptoms, diagnosis, and treatment options.