Can the HS (high sensitivity or quantitative) D-dimer test replace the fibrin split products (FSP) test? Why or why not? Also in pregnancy, since the D-dimer is always elevated, has any one tested and compared FSP levels in pregnancy as well? Thanks. Mohamed Emara, PhD, MT (ASCP)
Hello, Dr. Emara, and thank you for your question. The quantitative D-dimer is preferred over the time-honored semiquantitative fibrin degradation products (FDP), also called the FSP, for its speed and accuracy. Quantitative D-dimer is available with all automated coagulometers and is thus available in most institutions that provide coagulation testing. In addition, at least one manual quantitative D-dimer is available, the SimpliRed assay. There is no real instance where the FDP assay provides information that improves on or amplifies the D-dimer.
The quantitative D-dimer assay may be used to rule out venous thromboembolism in patients who experience associated symptoms such as chest congestion, but because a number of inflammatory conditions raise the D-dimer level, it cannot be used as conclusive evidence of deep venous thrombosis or pulmonary embolism. According toKrivak TC, Zorn KK. Venous thromboembolism in obstetrics and gynecology. Obstet Gynecol 2007;109:761-77, neither the D-dimer nor FDP is effective in diagnosing abruptio placentae.
Of course, if you are using the D-dimer to diagnose and monitor disseminated intravascular coagulation (DIC), which is the primary application of the FDP assay, it is effective in all instances, as D-dimer elevations in DIC are profound and far exceed inflammation or venous thromboembolism levels.