Anticoagulants and antiplatelet drugs are agents that reduce the ability of blood to form clots or coagulate. Blood clotting is a process triggered naturally in response to damage to blood vessels from injury or invasive procedures. Platelets within the blood become activated locally, resulting in an increased tendency to adhere to each other and to damaged blood vessel endothelium (primary haemostasis) . At the same time a cascade of reactions is initiated converting inactice coagulation factors to their active forms, ultimately leading to the production of the protein fibrin, the activated cross linking form of fibrinogen. Fibrin stabilises the primary platelet plug by cross-linking the platelets to each other and to the damaged blood vessel wall to prevent further blood loss (secondary haemostasis).
Anticoagulants and antiplatelet drugs exert their effects at different stages in the coagulation process. Antiplatelet drugs, including aspirin, dipyridamole and clopidogrel, interfere with plateletpe aggregation by reversibly or irreversibly inhibiting various steps in the platelet activationrequired for primary haemostasis. The various anticoagulant drugs inhibit the production or activity of the factors that are required for the coagulation cascade. For example warfarin and the other vitamin K antagonists (VKA; acenocoumarol and phenindione) work by inhibiting the vitamin K-dependent modification of prothrombin and other coagulation factors, which is required for their normal function , and in this way they impair secondary haemostasis.
Blood coagulation in response to injury is an essential process. However , certain medical conditions including atherosclerosis and cardiac arrhythmias, can predispose individuals to the risk of a thrombosis, where a blood clot (thrombus) blocks a blood vessel, with potentially catastrophic consequences such as heart attack, pulmonary embolism or stroke. Anticoagulants and antiplatelet drugs are prescribed to reduce the risk of such an event in patients with vascular, thromboembolic or cardiac conditions, a history of stroke or following surgical procedures such as heart valve replacements, cardiac stents and joint replacements. However this reduction in risk of thromboembolic events comes at the cost of an increased risk of bleeding, either spontaneously or associated with invasive procedures. The balance of these risks for an individual patient is the primary consideration in the management of dental patients who are taking anticoagulants or antiplatelet drugs and require dental treatment.
Assessing Bleeding Risk
Before providing dental treatment for a patient taking anticoagulants or antiplatelet drugs, their bleeding risk should be assessed. This involves consideration of both the likely risk of bleeding associated with the required dental procedure and the patient’s individual level of bleeding risk, which can be affected by the anticoagulants and antiplatelet drugs that they are taking, in addition to their other medical conditions and medications. These issues are addressed in the next section.
While the risk of bleeding complications associated with dental treatment for these patients should be taken seriously, it should be noted that existing evidence and clinical experience suggest that serious adverse bleeding events are rare. For example the incidence if significant bleeding after dental procedures (defined as that requiring an unplanned intervention including repacking and resuturing or transfusion in extreme cases) for patients who have continued their warfarin therapy perioperatively is estimated at less than 4%.
Which Dental Procedures have the Highest bleeding risk?
Table 1 categorises dental procedures into those that are unlikely under normal circumstances, to cause bleeding and those that can be expected to cause some level of bleeding. The management of patients taking anticoagulants or antiplatelet drugs whose dental treatment involves procedures from the first category should be straightforward and these patients can be treated according to standard practice with care taken to avoid causing bleeding. More careful consideration should be given to patients who require procedures likely to result in bleeding. Dental procedures that are likely to result in bleeding are further categorised in table 1 into those with a low risk of post operative bleeding complications and those that are judged to be more invasive and potentially carry a relatively higher risk of bleeding complications. By bleeding complications we mean prolonged or excessive bleeding or bleeding not controlled by initial haemostatic measures. Note that the use of the term ‘higher risk ‘ is not intended to suggest that these are high risk dental treatments.
Table 1 is intended to be a guide only and bleeding risk assessment for a patient’s dental treatment is likely to require further judgement on an individual case basis. Before performing a dental procedure that is likely to cause bleeding on a patient taking anticoagulants and antiplatelet drugs, the dentist or dental care professional should use their clinical judgement to determine whether they are sufficiently confident and skilled in the procedure and management of the associated peri-operative bleeding. If in doubt they should seek advice from or refer the patient to a more experienced colleague in primary or secondary dental care. This may be an experienced dental officer or a speciality dentist (oral surgery) or for very complex cases a consultant in dental care.
Dental Procedures that are UNLIKELY to cause bleeding
Dental Procedures that cause Bleeding with LOW risk of Post Operative Bleeding
Dental Procedures that Cause Bleeding with HIGH RISK Of Post Operative Bleeding
Local aneasthesia (LA)by infiltratrion intraligamentary or mental nerve block *
LA by inferior dental block or other regional nerve blocks **
Basic periodontal examination (BPE)***
Supragigival removal of plaque, calculus and stain
Direct or indirect restoration with supragingival margins
Impressions and other prosthetic procedures
Fitting and adjustment of orthodontic appliances
Simple extractions (1-3 teeth with restricted wound size)
Incision and drainage of intraoral swellings.
Detailed six point full periodontal examination
Root surface instrumentation(RSI) and subgingival scaling
Direct or indirect restorations with subgingival margins
Complex extractions, adjacent extractions that will cause a large wound or more than 3 extractions at once
Flap raising procedures:
- Elective surgical extractions
- Periodontal surgery
- Preprosthetic surgery
- Periradicular surgery
- Crown lengthening
- Dental implant surgery
*Local Anesthesia should be delivered using an aspirating syringe and should include a vasoconstrictor, unless contraindicated. Note that the other methods of LA are preferred over regional nerve blocks, whether the patient is taking an anticoagulant or not.
**here is no evidence to suggest that an inferior dental block perfored on an anticoagulated patient poses a significant risk of bleeding. However, for patients taking warfarin, if there are any indications that the patient has an unstable INR or other signs of excessive anticoagulation, an INR should be requested before the procedure.
***Although a BPE can result in some bleeding from gingival margins, this is extremely unlikely to lead to complications.
The arrest of bleeding is a core skill for primary dental care and the dental practitioner should have the necessary equipment and skills to perform appropriate local haemostatic measures competently for dental procedures likely to cause bleeding.These include packing any open sockets with haemostatic material and placing sutures. Suturing may be used to stabilise the clot, packing material and wound margins, unless it is likely to cause further trauma.
For all patients taking anticoagulants or antiplatelet drugs, haemostasis should be achieved using local measures prior to the patient being discharged from the care. Active consideration should be given to suturing and packing, taking into account all relevant patient factors. These may include the drug or drug combination that the patient is taking, other medical conditions or medication that may impact on bleeding and the travel time for the patient to access emergency care if required. Failure of initial haemostasis will necessitate packing and suturing at a later time.
Patients taking aspirin alone are unlikely to have a higher risk of bleeding complications than non anticoagulated patients and may not require suturing.
The dental practioner should have available:
- absorbent gauze
- haemostatic packing material ( oxidized cellulose, collagen sponge for example)
- suture kit (needle holders, tissue forceps, suture material and scissors)
General Advice for Managing Bleeding Risk
The following best practice advice is based on clinical experience and expert opinion
For a patient who is taking an anticoagulant or antiplatelet drug(s) and requires dental treatment that is unlikely to bleed (see table 1)
Treat the patient following standard procedures and taking care to avoid causing bleeding.
For a patient who is taking an anticoagulant or antiplatelt drug(s) that is likely to cause bleeding with low or higher risk of bleeding complications ;
-if the patient has another relevant medical condition(s) or is taking other medications that may increase bleeding risk , consult with patient’s general medical practiotioner or specialitst, if required for more information and in order to assess the likely impact on bleeding risk.
-If the patient is on a time limited course of anticoagulant or antiplatelet medication, delay non-urgent invasive dental procedures where prossible until the medication has been discontinued.
- if the medication is being taken in preparation for an elective surgical procedure it may be possible in a dental emergency to interrupt the drug treatment in liaison with the surgical consultant.
- Patients with acute deep vein thrombosis or pulmonary embolism may be taking high dose of apixaban or rivaroxaban for the first 1 to 3weeks of treatment. It should be advisable to delay any dental procedures likely to cause bleeding until the patient is taking the standard dose.
-Plan treatment for early in the day and week, where possible to allow time for the management of prolonged bleeding or rebleeding episodes should they occur.
-Perform the procedure as atraumatically as possible ,use appropriate local measures and only discharge the patient once haemostasis has been achieved.
-Advise the patient to take paracetamol unless contraindicated for pain relief rather than NSAIDs such as aspirin, ibuprofen, diclofenac or naproxen.
-Provide the patient with written post treatment advice and emergency contact details . Printable post treatment advice sheets are available at www.sdcep.org.uk
Treating a patient taking warfarin or another vitamin K antagonist
Although the use of warfarin is well established managing its therapeutic anticoagulation activity can be complicated. Due to substantial drug and dietary interactions, variation in patients’ responses to the drug and its narrow therapeutic range , warfarin activity has to be monitored frequently. This is achieved using the INR (International Normalised Ratio) test which measures the time taken for a clot to form in a blood sample, relative to a standard. An INR value 1 indicates a level of coagulation equivalent to that of an average patietn not taking warfarinm and values greater than 1 indicate a longer clotting time and thus a longer bleeding time. The INR test is also used for patients taking less commonly used VKAs acenocoumarol and phenindione.
Target INR levels differ depending on the indication for which the drug is prescribed and can range from 2.5-3.5 ±0.5. A patient’s warfarin therapy will be adjusted by their physician as necessary to achieve the target INR level appropriate for their medical condition. Warfarinised patients will have a record of their INR test results which they should present when attending for dental treatment.
For a patient who is taking warfarin or another vit K antagonist with an INR below 4, treat without interrupting their anticoagulant medication (strong recommendation, low quiality evidence – available in appendix 1 at www.sdcep.org.uk)
For dental treatment that is likely to cause bleeding complications :
- ensure that the patient’s INR has been checked ideally no more than 24h before the procedure. If the patient has a stable INR , checking the INR no more than 72h before is acceptable.
- if there is reason to believe that the test obtained up to 72h before dental treatment may not reflect the current level, the patient should be tested again no more than 24h before the dental procedure.
- If the patient’s INR is 4 or above, inform the patient’s medical practioner or anticoagulation service and delay treatment until the patient’s INR has been recuced to less than 4. For urgent treatment refer the patient to secondary dental care.
- If the patient’s INR is below 4 treat according to general advice for managing bleeding risk without interrupting their anticoagulant.
Source : https://www.sdcep.org.uk/wp-content/uploads/2015/09/SDCEP-Anticoagulants-Guidance.pdf
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