Deep vein thrombosis laboratory tests

Editors-in-Chief: C. Michael Gibson, M.S., M.D. Associate Editor-In-Chief: Ujjwal Rastogi, MBBS [mailto:urastogi@perfuse.org]

Overview
Deep vein thrombosis is a common condition seen in the Emergency Department. Standard of care for diagnosis of DVT includes a combination of a clinical pre-test probability rule known as Well's criteria, D-dimer blood testing, and Radiology department ultrasound.

D-dimer
 In a low-probability situation, current practice is to commence investigations by testing for D-dimer levels. This cross-linked fibrin degradation product is an indication that thrombosis is occurring, and that the blood clot is being dissolved by plasmin. A low D-dimer level should prompt other possible diagnoses (such as a ruptured Baker's cyst, if the patient is at sufficiently low clinical probability of DVT.

It should be noted that latex D-dimer assays are insensitive and have no role in screening for deep vein thrombosis.

Other blood tests
Other blood tests usually performed at this point are:
 * complete blood count
 * Primary coagulation studies: PT, APTT, Fibrinogen
 * liver enzymes
 * renal function and electrolytes
 * prostate specific antigen measurement in men over the age of 50.