| Abstract: | Pulmonary embolism is a potentially fatal condition that is extremely difficult to accurately diagnose clinically, usually relying on radiological investigations to make the diagnosis. These confirmatory tests are expensive, time consuming and may be associated with considerable morbidity. Thus, the utility of a blood test that reliably makes or refutes the diagnosis is apparent. Most blood tests involve the later stages of thrombolysis. Of these, the D-Dimer tests are the most sensitive, and when combined with monoclonal antibody technology, are of clinical value. Enzyme-linked immunosorbent assay D-Dimer tests have good sensitivity (95%) and moderate specificity (30–45%), but technical considerations prevent their routine use. Latex agglutination tests overcome these technical problems, but their sensitivity is variable (46–100%). Two recently introduced tests show promise. The NYCO-CARD D-Dimer test is a semiquantitative modified enzyme-linked immunosorbent assay test. Relatively few clinical studies have been performed and further validation studies are required. The SimpliRED D-Dimer test uses a new bispecific antibody technique, allows bed-side testing, and has good sensitivity (84–100%) and negative predictive values (92–99%). These tests could be used to screen low risk patients, thus avoiding ventilation-perfusion scans, or in combination with ventilation-perfusion scans and lower limb studies to avoid angiograms in intermediate probability pulmonary embolism patients. Future research will define where these tests show greatest utility, particularly in which patient subgroups, or symptom time intervals. |
