Low–risk patient had stroke when taken off medication to thin his blood

What happened

Mr B suffered from atrial fibrillation (a fast and erratic heartbeat) and was taking medication to thin his blood. He needed a colonoscopy (an examination of the inside of the colon), and a week before he was due to have the procedure the Trust told him to stop taking warfarin (an anticoagulant that slows the rate at which blood clots). Mr B had a stroke the day before he was due to have the procedure. This left him with slurred and slowed speech.

Mr B complained to the Trust. It told him that he had been a low?risk patient and it had followed its standard practice in advising him to come off warfarin for seven days. It was sorry for his situation.

The Trust explained there was a national debate about the best way to balance the risks for patients on warfarin who needed a colonoscopy. When doctors do a colonoscopy, they sometimes need to remove polyps (growths on the lining of the colon) at the same time. Warfarin increases the risk of bleeding during this procedure. There was no clear research evidence of the best way to balance the risk of bleeding against the risk of blood clots and stroke.

What we found

We did not uphold this complaint, although we had every sympathy with Mr B's situation. The Trust had followed its local policy, which was within the range of good practice from a clinical perspective. There are national guidelines that state that a patient should only come off warfarin for five days before an endoscopy (a colonoscopy is a type of endoscopy). However, other guidelines were less clear cut and the Trust's rationale for deciding on a seven–day period was not unreasonable. The Trust was correct to say that there was no definitive evidence of the best way to balance the risks. This was a very difficult set of issues from a clinical point of view.

It was not possible to say whether being off warfarin caused the stroke, as a small proportion of patients will have a stroke even though they are on anticoagulants. Mr B was placed at a slightly increased risk as a result of being off warfarin for seven days rather than five, but it was not possible to be specific about that. In addition, warfarin needs to be taken for several days to become fully effective. Even if it had been restarted on day five, it would not have fully taken effect by the time Mr B had his stroke.

Putting it right

The Trust agreed to produce an information leaflet for patients who took warfarin and who were to have endoscopic procedures. It also agreed to write to Mr B again to acknowledge his situation and express its sympathy.