Removable plastic stents are used in uncomplicated gallstone disease, while permanent blood clotting is impaired, as the risk of bleeding ( especially from sphincterotomy ) is increased in the use of medication such as clopidogrel ( which inhibits platelet aggregation ) or if the prothrombin time is significantly prolonged.
32.
The INR was invented in the early 1980s by Tom Kirkwood working at the UK National Institute for Biological Standards and Control ( and subsequently at the UK National Institute for Medical Research ) to provide a consistent way of expressing the prothrombin time ratio, which had previously suffered from a large degree of variation between centres using different reagents.
33.
The reference range for "'prothrombin time "'depends on the analytical method used, but is usually around "'12 13 seconds "'( results should always be interpreted using the reference range from the laboratory that performed the test ), and the "'INR "'in absence of anticoagulation therapy is "'0.8-1.2 " '.
34.
Medicare coverage for home testing of INR has been expanded in order to allow more people access to home testing of INR in the USA . The release on 19 March 2008 said, " [ t ] he Centers for Medicare & Medicaid Services ( CMS ) expanded Medicare coverage for home blood testing of prothrombin time ( PT ) International Normalized Ratio ( INR ) to include beneficiaries who are using the drug warfarin, an anticoagulant ( blood thinner ) medication, for chronic atrial fibrillation or venous thromboembolism . " In addition, " [ t ] hose Medicare beneficiaries and their physicians managing conditions related to chronic atrial fibrillation or venous thromboembolism will benefit greatly through the use of the home test ."
