A new guideline from the American Academy of Neurology advises that it is likely safe for patients to continue taking blood thinners like aspirin or warfarin before minor procedures such as a cataract operation, minor dental surgery or dermatological procedure.

Developed with financial support from the American Academy of Neurology, the guideline appears in the 28 May issue of Neurology, the Academy’s official journal.

One of the co-authors, Jose Biller, chair of the Department of Neurology of Loyola University Medical Center in Maywood, Illinois, says in a statement:

“This guideline is expected to be useful to neurologists, primary care physicians, surgeons, dentists and other healthcare providers caring for these patients.”

After experiencing a stroke or mini-stroke, many patients are prescribed blood thinners such as aspirin or warfarin (commonly branded as Coumadin) to reduce the risk of blood clots that could give them another stroke.

The downside of this is that blood thinners increase the risk of bleeding when the patient requires surgery. So patient and doctor are then faced with a dilemma: how to weigh up the risk of bleeding against the benefits of the surgery (or the future harm that not having the surgery might pose)?

After systematically reviewing evidence from 133 studies, Biller and colleagues concluded that on the whole, it is likely safe to continue taking them before minor procedures, but it depends on the blood thinner and type of procedure.

The guideline is set out as a series of “levels” ranging from very unlikely that the procedure increases risk of bleeding, through possibly does not, to uncertainty about the risk due to lack of research.

For instance:

  • Taking warfarin or aspirin before dental procedures is very unlikely to increase risk of bleeding.
  • Taking aspirin before minor procedures like cataract surgery, carpal tunnel syndrome surgery, dermatologic procedures and prostate biopsy likely does not increase bleeding risk.
  • Taking warfarin before dermatologic procedures and invasive ocular anesthesia also likely does not increase bleeding risk.
  • Taking aspirin before procedures such as retinal surgery and ultrasound-guided biopsy possibly does not increase bleeding risk.
  • But taking aspirin before orthopaedic hip procedures is likely to increase bleeding risk.

To help healthcare providers apply the guidelines, the authors give three examples of hypothetical cases where patients have had a stroke and are due to undergo a surgical procedure:

  1. 65-year-old man due for routine colonoscopy screening. The patient had a stroke about a year ago. He may or may not need to have a polyp removed and the risk of bleeding if he does is 2%. His neurologist recommends he continues to take aspirin.
  2. 70-year-old woman with breast cancer due to undergo mastectomy. The patient had a stroke before the breast cancer and is taking aspirin. As there is little published research on the bleeding risk of taking aspirin before such an invasive procedure, the patient and her neurologist agree she should stop taking the aspirin seven days before the surgery and resume the day after.
  3. 60-year-old man due to undergo cataract surgery. The patient is taking warfarin following a stroke. After consulting the guidelines, his neurologist discovers the risk of bleeding during an eye procedure while taking warfarin is not precisely defined. But the patient says he would rather risk the bleeding than risk another stroke, so he, the ophthalmologist and neurologist agree he should continue to take warfarin when he has the cataract surgery.

In the February 2012 issue of Expert Reviews, Loyola University Medical Center physicians report finding that for atrial fibrillation patients at risk for stroke, easy-to-use blood thinners are likely to replace Coumadin.

Written by Catharine Paddock PhD