ECCO Caring For Patients With Cardiovascular Disorders Part 1 Practice Test

D-dimer testing is most useful for ruling out thromboembolism rather than confirming it. The test is very sensitive for clot formation and breakdown, so a negative result strongly argues against a PE or DVT in patients who are low risk. This gives a high negative predictive value, meaning you can often avoid imaging in those low‑probability cases. However, D-dimer has low specificity. Many non-thrombotic factors—such as infection, inflammation, cancer, recent surgery, age, or pregnancy—can raise D-dimer levels. Because of that, a positive result does not confirm PE or DVT; it simply raises suspicion and usually leads to imaging to establish a diagnosis. In practice, you combine pretest probability with D-dimer results: if risk is low and the D-dimer is negative, you can rule out clot. If risk is intermediate or high, or if the D-dimer is positive, you proceed to definitive imaging (like CT pulmonary angiography for PE or compression ultrasound for DVT). Age-adjusted thresholds can help improve specificity in older patients.