can a bloud test detect a bloud clot

Hi,
Blood tests may be done to check if there is chance of blood clotting or hypercoagulability. This type of testing includes Activated protein C resistance,Antithrombin III and Screening for disseminated intravascular coagulation (DIC). These test are not used to diagnosis a blood clot.
Blood clots are diagnosed with the use of ultrasound, venography, CT scan and a ventilation perfusion scan.
Sometimes, a blood test is used to screen for blood clots. D-Dimer is a breakdown product of a blood clot, and its levels in the bloodstream may be measured. Blood clots are not stagnant; the body tries to dissolve them at the same time as new clot is being formed. D-Dimer is not specific for a blood clot in a given area and cannot distinguish a "good” or needed blood clot, one that forms after surgery or due to bruising from a fall, from one that is causing medical problems. It is used as a screening test with hopes that the result will be negative and show that there is no need to look further for blood clots.
The D-dimer blood test is usually ordered with the expectation that it will be negative. It is a useful test in patients who have a low probability of having a blood clot, and the health care practitioner usually counsels the patient that a positive blood test will likely require additional tests being ordered.
Thanks for your question.
Maryann