The clotting is a natural process that is required to stop bleeding. However, your body requires more than 12 blood proteins and factors to start clotting. And, lack of certain factors may delay this natural process and lead to abnormal bleeding, such as hemophilia.

However, there exist several conditions that give rise to the clotting problems. For example, you may develop certain conditions, such as as antiphospholipid antibody or lupus anticoagulant syndrome within your immunity system that hamper this natural process. These syndromes may develop because the immunity system synthesizes the antibodies that attack the blood clotting factors. Thereofore, it may happen that the blood easily clots in the veins and arteries.

The Activated Partial Thromboplastin Time (aPTT) test is recommended for people with a history of bleeding disorders. However, it also recommended for people with arterial or venous thrombosis and repetitive abortions. If the test values are abnormal, further tests may be required to identify the exact cause of the coagulation problem.

The aPTT is often conducted before a surgical procedure. If you taking an anticoagulant or blood thinner called heparin, you may require to undergo this test to ensure that you are getting the right dosage. In such cases, an aPTT is required after regular intervals until the correct dosage of medicine is given.