Normal blood D-dimer concentrations: do they exclude pulmonary embolism?

Area of Science:

• Medical Diagnostics
• Cardiology
• Pulmonology

Background:

• Pulmonary embolism (PE) diagnosis often relies on D-dimer (DD) testing.
• Normal DD concentrations typically rule out PE, but cases with normal DD may be underestimated.
• Overlooking PE can lead to severe consequences.

Purpose of the Study:

• To investigate the incidence and clinical characteristics of PE in patients with normal DD concentrations.
• To compare patients with PE and normal DD to those with PE and abnormal DD.

Main Methods:

• Retrospective analysis of 29 patients with PE and normal DD over seven years.
• Comparison of clinical features between PE patients with normal vs. abnormal DD.
• Evaluation of pretest probability scores (Wells, revised Geneva).

Main Results:

• The incidence of normal DD in PE patients was 4%.
• Patients with normal DD and PE were more likely to have a prior PE history.
• Fever, tachycardia, and tachypnea were less frequent; symptom onset to DD testing interval was longer in the normal DD group.

Conclusions:

• PE with normal DD is rare but occurs, with a 4% incidence in this study.
• A combination of pretest probability scores and normal DD aids diagnosis but doesn't exclude PE.
• Consider PE in patients with prior PE or prolonged symptom onset to testing intervals, especially if clinical manifestations are unexplained.