The Terminology- SNOMED CTÂ®, an Evolving Clinical Reference Terminology. SNOMEDÂ® is the Systemized Nomenclature of Medicine. It is a controlled medical terminology (CMT). At its simplest, a SNOMED is a coded vocabulary of medical concepts and expressions used in healthcare.
The partial thromboplastin time (PTT) is a screening test that helps evaluate a person's ability to appropriately form blood clots. It measures the number of seconds it takes for a clot to form in a person's sample of blood after substances (reagents) are added.
What It Is. A partial thromboplastin time (PTT) test measures how long it takes for a clot to form in a blood sample. A clot is a thick lump of blood that the body produces to seal leaks, wounds, cuts, and scratches and prevent excessive bleeding. The blood's ability to clot involves platelets (also called thrombocytes) and proteins called clotting factors.