If in case you are not familiar with what these two are, you should know that these are laboratory tests. PT stands for Prothombrin Time, while PTT will stand for Partial Prothrombin Time. PT will be used in order to measure the extrinsic system.
This will also be used to check out the various factors that are available. When you say PTT, this stands for the intrinsic system and also some of the components that are available. Take note that these are tests that you may need to undergo, especially if it has been ordered by your doctor before surgery.
Another test that your doctor may ask you to take is IR, also known as International Normalized Ratio.