D-Dimer Tests in the Emergency Department: Current Insights

Abstract

In the Emergency Medicine setting, D-dimer is currently employed in the diagnostic assessment of suspected venous thromboembolism and aortic syndrome. The nonspecific symptoms reported by patients, like chest pain, dyspnea or syncope, uncover a wide range of differential diagnosis, spanning from mild to life-threatening conditions. Therefore, we assumed the perspective of the Emergency Physician and, in this narrative review, we reported a brief presentation of the epidemiology of these symptoms and the characteristics of patients, in whom we could suspect the aforementioned pathologies. We also reported in which patients D-dimer gives useful information. In fact, when the probability of the disease is high, the D-dimer level is futile. On the contrary, given the low specificity of the test, when the probability of the disease is very low, a false-positive value of the D-dimer only increases the risk of overtesting. Patients with low to moderate probability really benefit from the D-dimer testing, in order to prevent the execution of expensive and potentially dangerous imaging tests. In the second part of the review, we focused on the prognostic value of the test in septic patients. The early prognostic stratification of septic patients remains a challenge for the Emergency Physician, in the absence of a definite biomarker or score to rely on. Therefore, we need several parameters for the early identification of patients at risk of an adverse prognosis and the D-dimer may play a role in this demanding task. SARS COVID-19 patients represent an emerging reality, where the role of the D-dimer for prognostic stratification could be relevant. In fact, in patients with severe forms of this disease, the D-dimer reaches very high values, which appear to parallel the course of respiratory failure. Whether the test may add useful information for the management of these patients remains to be determined.

Keywords: COVID-19; aortic syndromes; diagnostic assessment; prognostic stratification; sepsis; venous thromboembolism.

Figure 1

The process of D-dimer generation: 1) Thrombin cleaves fibrinopeptides from fibrinogen monomer (A); 2) Fibrin monomers aggregate (B); 3) Fibrin monomers are cross-linked by factor XIIIa, that stabilizes the fibrin polymer (C); 4) fibrin is degraded by plasmin, releasing D-dimer and fibrinogen degradation products (FDP) (D).

Figure 2

Diagnostic pathways in patients with suspected PE based on WELLS and GENEVA scores.

Figure 3

Diagnostic pathway in patients with suspected AAS.

Figure 4

Coagulation abnormalities during sepsis.

Figure 5

Trends of PaO₂/FiO₂ (P/F) ratio (A) and D-dimer (B) in survivors and non-survivors during the first days of the treatment with non-invasive ventilation for acute respiratory failure, in patients affected by SARS COVID-19.