Home' News Bulletin : ADA News Bulletin September 2015 Contents 17
Warfarin, extractions and
Earlier this year, the Western Australian Coroner found that
a 68 year old female patient died from acute haemorrhage
secondary to bilateral dental extraction.
The patient, who was taking the anticoagulant medication
warfarin due to the presence of a prosthetic cardiac valve,
underwent forceps extraction of two periodontally involved teeth
(16 and 26) under local anaesthesia. Haemostasis was achieved
and the dentist issued verbal post-operative instructions and
supplied the patient with gauze pads prior to her leaving the
surgery. The patient, who lived alone, was found deceased at
home approximately 36 hours later. Apparently, she had not
sought emergency treatment during that time.
The Coroner was critical of the dentist in two main areas: failure to
obtain a blood test for the patient’s International Normalised Ratio
(INR) within the 24 hours prior to the extractions; and failure to
give the patient written post-operative instructions to accompany
the verbal instructions.
The current Therapeutic Guidelines: Oral and Dental* recommends
warfarin should not be stopped prior to extraction. Although
there is a risk of post-operative bleeding, the risk of a catastrophic
thromboembolic event, such as stroke, occurring if warfarin is
stopped is considered a much more serious risk. Therapeutic
Guidelines: Oral and Dental* sets out a number of measures to be
used for patients on warfarin undergoing dental extraction. One
important measure is for the patient’s INR to be assessed within
24 hours before the procedure.
The INR test assesses the anticoagulant effect of warfarin with the
target usually being 2.5 (therapeutic range 2.0 to 3.0), although
a target of 3.0 (therapeutic range 2.5 to 3.5) may sometimes be
required.* The higher the INR, the longer it takes for coagulation
to occur and therefore the risk increases of bleeding. A patient’s
response to warfarin is driven primarily through genetic variance in
hepatic clearance and vitamin K handling; and with diet, age and
dose also influencing the anticoagulant effect.* If a patient has
an INR well above the indicated therapeutic range, it is prudent
to refer them to their physician for management of their warfarin
therapy and delay extraction until the INR reduces back into the
therapeutic range. Therapeutic Guidelines: Oral and Dental*
recommend that if a patient has an INR above 4.0, extraction
should not be performed and the patient should be referred to
their medical practitioner. If post-operative haemorrhage does
occur and cannot be controlled with local measures, the patient
requires emergency referral to hospital where the effects of
warfarin can be reversed by administration of vitamin K.
It is recommended that written post-operative instructions be
given to all patients following dental extractions in addition
to verbal instructions. Patients may not always recall verbal
instructions or may not clearly understand what they have been
told. Providing written instructions is important for patients taking
anticoagulants such as warfarin or the newer oral anticoagulants,
or anti-platelet medications, given the serious outcomes which
may occur due to uncontrollable bleeding. Written instructions
should provide after-hours contact numbers for the dentist and
also provide clear instructions to attend a hospital emergency
department or ring triple zero in the event the dentist cannot
be reached. If a practice, clinic or institution does not have its
own post-operative instruction sheet, these may be purchased
commercially. The Mi-tec patient instruction brochure Dental
Extractions* is one example providing post-operative instructions
and a dentist can include contact phone numbers. Always
record in the patient’s clinical record that written post-operative
instructions have been provided and explained to the patient.
In addition to the guidelines set out in Therapeutic Guidelines:
Oral and Dental,* the following checklist should be used for
management of patients taking warfarin:
1. Patient’s medical and medication history should be checked.
Drug interactions with warfarin can increase the INR (e.g. the
2. Check patient’s INR the day before the procedure or on the day
of the procedure to ensure it is not above the therapeutic range.
3. Pack the socket(s) with absorbent or non-absorbent haemostatic
4. Suture the socket(s). Apart from providing compression, the
suture assists in retaining the clot.
5. Apply pressure and compression to the socket(s) until bleeding
6. Encourage patients to have a responsible adult accompany
them to their appointment and stay with them after the procedure
for at least the first 24 hours. This is important if they normally live
alone, or if they are elderly.
7. Provide written post-operative instructions, in addition to verbal
instructions, to both the patient and accompanying adult.
8. Ensure patients with a language difficulty understand the post-
operative instructions or have someone with them to explain it to
9. Provide patients with phone numbers, including after-hours
10. Advise patients to contact the dentist or oral surgeon if necessary.
11. Arrange to see the patient, or at least follow up by phone, the
day following the procedure.
Many patients who are taking warfarin may be elderly and may
also have other health issues, the recommendation is for the
patient to be monitored at home by a responsible adult for the
first 24 hours is considered very important.
Dental Therapeutics Committee
*Mi-tec Medical Publishing, www.adabookshop.com/
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