blood clot

I have a question about a blood test I ahad a d-dimer done and it was negative I was wondering how accurate they are. My leg is a little swollen 1cm and some pain. what could it be please responde if you have any information for me thank you.

[Dr Vinod]

D-dimer testing is of clinical use when there is a suspicion of deep venous thrombosis (DVT) or pulmonary embolism (PE). In patients suspected of disseminated intravascular coagulation (DIC), D-dimers may aid in the diagnosis.In some hospitals, they are measured by laboratories after a form is completed showing the probability score and only if the probability score is low or intermediate. This would reduce the need for unnecessary tests in those who are high-probability.
Leg can swell due to hypertension/cellulitis/ etc. As you are also having pain, i think it is inflammed due to infection and you should get yourself examined and take an antibiotic course. What is the amount of pain? inflammation etc can only be clear with examination. Take care!