Final answer:
Partial thromboplastin time (PTT) is a laboratory test used to evaluate the blood's ability to form clots. It is commonly used to monitor the effectiveness of anticoagulant medications like heparin and to diagnose and monitor bleeding disorders.
Step-by-step explanation:
Partial thromboplastin time (PTT) is a laboratory test used to evaluate the blood's ability to form clots. It measures the time it takes for clot formation after adding specific reagents to the blood sample. PTT is commonly used to monitor the effectiveness of anticoagulant medications like heparin and to diagnose and monitor bleeding disorders. For example, if a person has hemophilia, they may have an abnormally prolonged PTT.