While labs don't generally offer prothrombin time tests, sometimes called PT or ProTime tests, to the public, they do perform the tests at the request of physicians. Doctors order prothrombin time tests to find a cause for unexplained bleeding, as Lab Tests Online explains.
Doctors order occasional prothrombin time tests for patients taking warfarin, an anticoagulant drug, to make sure the drug is working properly. They order the test for patients who display signs of any kind of bleeding disorder. They also routinely order the test before a patient undergoes surgery to make sure the patient's blood clots normally, notes Lab Tests Online. Ingestion of alcohol and certain foods and drugs sometimes affects the results of a prothrombin test.