Which lab test is critical in the assessment of a suspected pulmonary embolism (PE)?

The D-dimer test is critical in the assessment of a suspected pulmonary embolism (PE) because it measures the level of fibrin degradation products in the blood. When a thrombus (or clot) is present, such as in the case of a pulmonary embolism, fibrin is broken down, resulting in elevated levels of D-dimer. This test is particularly useful because it can help rule out PE; low D-dimer levels are associated with a very low probability of PE, allowing healthcare providers to effectively exclude the diagnosis in patients with a low clinical probability of the condition.

In higher-risk patients, elevated D-dimer levels can further prompt the need for imaging studies (such as a CT pulmonary angiography) to confirm the presence of a PE. While other tests like the complete blood count, creatinine level, and coagulation profile are important for assessing different aspects of a patient’s condition, they do not have the same direct relevance in specifically diagnosing or ruling out pulmonary embolism as the D-dimer test does.