Put simply a D-Dimer test is meant to detect the possibility of DVT (Deep Vein Thrombosis), PE (Pulmonary Embolism), or DIC (Disseminated Intravascular Coagulation).
D-Dimers are small protein fragments that are produced when your body dissolves clots. This is a normal process called fibrinolysis, your body uses the fibrinolytic system to repair blood vessels and small capillary ruptures constantly.
If they are increased, it points towards a thrombolytic event that should be investigated.
If the D-Dimer level is normal, then the presence of a thrombolytic event is reduced to 1%.