Diagnostic accuracy of D-dimer assay in suspected pulmonary embolism patients

BackgroundPulmonary embolism (PE) is a frequent and potentially severe disease. So objective testing is required to establish or exclude the presence of pulmonary embolism.AimThis study was carried out to evaluate the diagnostic accuracy of D-dimer test in suspected pulmonary embolism patients.Patients and MethodsThis study was carried out on 30 patients with clinical and radiological signs suspicious of PE. All cases were subjected to the following: evaluation of clinical probability by Revised Geneva Score, plain chest X-ray, CT pulmonary angiography (CTPA), electrocardiographic examination, arterial blood gases analysis, calculated alveolar arterial oxygen (PA-aO2) gradient, duplex ultrasonographic, D-dimer assay, and measurement of partial end tidal carbon dioxide (PetCO2).ResultsPE confirmed in 22 cases by CTPA, 20 cases of PE (91%) had positive D-dimer and 2 cases (9%) had negative D-dimer test. The sensitivity, specificity and accuracy of D-dimer in diagnosis of PE were (90%, 37.5%, and 26.6%) respectively. The sensitivity of D-dimer in evaluation of PE when clinical probability of PE low or intermediate was (100%), its specificity was (37.5%), its negative predictive value (NPV) was (100%) and its positive predictive value (PPV) was (67.7%), while in high clinical probability its sensitivity was (83.3%), specificity was (100%) and its PPV was (100%). There was statistically significant difference among the negative and positive PE cases as regards the PetCO2 result (P < 0.05). The sensitivity of PetCO2 in diagnosis of PE was (68%) its specificity was (87.5%), NPV was (50%) and its PPV was (93.7%).ConclusionD-dimer alone cannot exclude or confirm the presence of PE. The combination of D-dimer, PetCO2 ⩽28.5 mmHg and the clinical probability could improve diagnostic accuracy in patients with suspected PE.