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.
The PTT may be ordered along with other tests such as a PT when a person has: 1  Unexplained bleeding or easy bruising. 2  A blood clot in a vein or artery. 3  An acute condition such as disseminated intravascular coagulation (DIC) that may cause both bleeding and clotting as coagulation factors are used up at a rapid rate.he PTT may not be prolonged until the factor levels have decreased to 30% to 40% of normal. Also lupus anticoagulant may be present but may not prolong the PTT result. If the lupus anticoagulant (LA) is suspected, a more sensitive LA-sensitive PTT or a dilute Russell viper venom time (DRVVT) can be used to test for it.