D-dimer test

A blood test called a D-dimer can be used to assist in ruling out the possibility of a dangerous blood clot. Your body performs a number of actions to cause your blood to clot when you get cut. Without it, you’d keep bleeding and have a much bigger issue. It’s a standard component of healing. You no longer require the clot once the bleeding has stopped. Your body then moves in a number of opposite directions to dissolve the clot.

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After all of that, you still have certain things floating about in your blood, just like how you would have wood dust all over the place during a construction project. D-dimer is the name of one of such byproducts. It is a protein component. Usually, it disappears with a little bit of time. However, if you have a significant clot, such as deep vein thrombosis, you may see elevated amounts of D-dimer in your blood (DVT). When you have a deep vein clot (DVT), it commonly occurs in your legs and can cause significant issues.

In order to determine whether you might have a blood clot, your doctor may conduct this test, which measures the amount of D-dimer in your blood. This test may also be referred to as:

• D-dimer fragment test
• Test for fibrin degradation fragments

What Happens During the D- Dimer Test?

A D-dimer test does not require any extra preparation on your part. Your doctor takes a little blood with a fine needle. When the needle is inserted, you can feel a squeeze or stinging. Where the blood is drawn, you might have some soreness or bruising, but that is typically all.

Usually, you get results right away. In emergency rooms, this test is frequently applied.

What Do the Findings Indicate?

The test may be performed differently by different labs, therefore be aware that what is normal may change. Your doctor can explain your results to you in more detail.

If your test result is “negative,” you probably don’t have a blood clotting issue, such as DVT.

You will require more tests to determine whether you have a blood clot if your result is “high.” Your presence of DVT or PE cannot be verified by this test. It can only aid in eliminating them.

In addition to a clot, additional conditions like these could potentially cause a high result:

• Infection
• liver illness
• some cancers

Pulmonary embolism (PE), deep vein thrombosis (DVT), or disseminated intravascular coagulation are examples of probable diagnosis (DIC).

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Clinical significance

D-Dimer test for Pulmonary Embolism (PE)

A blood clot within the pulmonary vasculature that causes a reduction in blood flow downstream of the clot is referred to as a pulmonary embolism. While some individuals may experience tiny pulmonary emboli with few symptoms, others may experience big pulmonary emboli that completely obstruct one or more of the main pulmonary arteries. A saddle embolism is a type of pulmonary embolism that occurs when the main pulmonary arteries are involved bilaterally. A saddle embolus patient has a high chance of cardiopulmonary arrest and passing away. When a patient exhibits symptoms or signs such as chest discomfort, breathlessness, or hypoxia, getting a D-dimer might aid in examining the differential diagnosis.

Low-risk patients should have a D-dimer test performed, and PE can be reasonably ruled out in these patients if the test results are negative. Instead of using the D-dimer as a screening test in high-risk patients (which includes those in whom you have a strong clinical suspicion for PE), imaging should be acquired. In patients at moderate risk, one can either get a D-dimer (a negative D-dimer would rule out PE) or, if clinical suspicion is still strong, proceed directly to imaging.

A CT angiography or ventilation-perfusion scan should be used for further evaluation in patients who are at high risk for PE or who have a positive D-dimer.

D-Dimer test for Deep Vein Thrombosis (DVT)

A deep venous thrombus (DVT) is a blood clot that develops in the arms or legs. The legs are where they are most frequently found. Erythema, discomfort, oedema, and increased temperature in the afflicted extremity are all signs of DVT. The Wells Criteria for DVT also provides a risk-stratification score for DVT. This scoring method takes recent cancer, recent immobility (including recent surgery), asymmetric leg oedema, the existence of collateral veins, discomfort around the suspected vein’s location, previously identified DVT, and a strong clinical suspicion for DVT into account.

With the help of this scoring method, one can be categorized as “likely” or “unlikely” to develop DVT or as having low, moderate, or high risk. In either case, a negative D-Dimer in the low-risk or “unlikely” groups can rule out a DVT. A positive D-Dimer requires ultrasound imaging in the moderate-risk, high-risk, or “likely” groups to assess for DVT. Again, though, one can schedule an ultrasound without first acquiring a D-Dimer if there is a strong clinical suspicion of DVT.

D-Dimer for Disseminated Intravascular Coagulation (DIC)

A malfunction with the coagulation cascade leads to diffuse intravascular coagulation. If the process develops slowly, it may result in excessive clot formation, while if it develops quickly, bleeding may result. The mortality rate for DIC is substantial. One of the numerous various studies that can be requested as part of the diagnostic workup for DIC is a D-dimer.

If a patient has DIC, their D-dimer will be highly increased. The platelet count (low), PT/INR (normal to extended), fibrinogen (depressed to normal), and PTT are other labs that one might think about getting (normal or elevated). These labs can also be used to track how DIC treatment is working because they should start to return to normal with recovery and ideally DIC.

Diagnostic algorithm based on initial D-dimer testing for the exclusion of VTE with additional imaging tests only in patients with a positive D-dimer result. Image source: Prisco, D., & Grifoni, E. (2009, February). The role of D-dimer testing in patients with suspected venous thromboembolism. In Seminars in thrombosis and hemostasis (Vol. 35, No. 01, pp. 050-059). © Thieme Medical Publishers.

Do I need to know anything else about a D-dimer test?

Your doctor may request one or more imaging tests to determine whether you have a clotting disorder if the findings of your D-dimer test were abnormal. These consist of:

Doppler ultrasound is a technique that produces images of your veins using sound waves.
angiograms using CT. You undergo this test after receiving an injection of a specific dye that makes your blood vessels more visible on a certain kind of x-ray machine.
V/Q scan for ventilation-perfusion. These two tests can be performed separately or jointly. Both of them employ trace amounts of radioactive materials to aid a scanning device in determining how well your lungs function.

Summary

A blood test called a D-dimer can be used to assist in ruling out the possibility of a dangerous blood clot. Your body performs a number of actions to cause your blood to clot when you get cut. Without it, you’d keep bleeding and have a much bigger issue. If you have a clot, such as deep vein thrombosis, you may see elevated amounts of D- dimer in your blood (DVT). This test may also be referred to as the D-dimer fragment test

Low-risk patients should have a D-dimer test performed, and PE can be reasonably ruled out in these patients if the test results are negative. CT angiography or ventilation-perfusion scan should be used for further evaluation in patients who are at high risk for PE. The Wells Criteria for DVT also provides a risk-stratification score. A negative D-Dimer in the low-risk or “unlikely” groups can rule out a DVT. The platelet count (low), PT/INR (normal to extended), fibrinogen (depressed to normal), and PTT are other labs that one might think about getting.

Keep reading for more!

Team MBD

Watch more- What the D Dimer test tells you. – YouTube