Home :: D-dimer
A D-dimer is an asymmetrical carbon compound fragment formed after thrombin converts fibrinogen to fibrin, factor XIIIa stabilizes it into a clot, and plasma acts on the cross-linked, or clotted, fibrin. The test is specific for fibrinolysis because it confirms the presence of fibrin split products.
- To diagnose disseminated intravascular coagulation (DIC).
- To differentiate subarachnoid hemorrhage from a traumatic lumbar puncture in spinal fluid analysis.
- Obtain the patient's history of hematologic diseases, recent surgery, and the results of other tests performed.
- Explain to the patient that the test is used
to determine if the blood is clotting normally.
- Tell him that the test requires a blood sample. Explain who will perform the venipuncture and when.
- Reassure him that drawing a blood sample will take less than 3 minutes.
- Explain that he may feel slight discomfort from the tourniquet pressure and the needle puncture
Procedure and posttest care
- Perform a venipuncture and collect the sample in a 5-ml blue-top tube.
- For a spinal fluid analysis, the sample is collected during a lumbar puncture and placed in a plastic vial.
- Apply pressure to the venipunclure site for 5 minutes or until bleeding stops.
- If a hematoma develops at the venipuncture site, apply warm soaks.
- Completely fill the collection tube, invert it gently several times, and send it to the laboratory immediately.
- For a patient with coagulation problems, you may need to apply additional pressure at the venipuncture site to control bleeding.
Normal D-dimer test results are negative or < 250 ug/ml).
Increased D-dimer values may indicate DIC, pulmonary embolism, arterial or venous thrombosis, neoplastic disease, pregnancy (late and postpartum), surgery occurring up to 2 days before testing, subarachnoid hemorrhage (spinal fluid only), or secondary fibrinolysis.
- Failure to fill the collection tube completely or to send the sample to laboratory immediately.
- Hemolysis due to rough handling of the sample.
- High rheumatoid factor titers or increased CA-125 levels (possible falsepositive).
- Spinal fluid analysis in infants under age 6 months (possible false-negative).