If the prothrombin time test is analyzed in an on-site lab, the results may be available within 24 to 72 hours. If the doctor sends the sample to an off-site lab, results generally take longer, and the patient may want to ask the doctor when to expect the report.
Some patients undergoing anticoagulant therapy need to perform the pro-time test at home about once a week. The FDA approves of four home-testing devices, including the Roche Diagnostics CoaguChek S Prothrombin Time Monitoring System for home use.
This system requires only a small sample taken from a fingerstick. The patient typically sees results on the LED screen in about one minute, which facilitates prompt anticoagulant therapy adjustment.