Sensitivity and specificity of chest ultrasound in the diagnosis of pulmonary embolism in the emergency department: A case-control study

OBJECTIVES: The present study was designed to evaluate the role of chest ultrasound in the diagnosis of acute pulmonary embolism (PE) and determine its accuracy using multi-detector CT-pulmonary angiography (MD-CTPA) as a gold standard technique for PE diagnosis. PATIENTS AND METHODS: A prospective case-control study was performed with 75 patients who presented to the emergency department of Minia Cardiothoracic University Hospital with clinical suspicion of PE. All patients were evaluated clinically and by laboratory tests to assess the risk of PE. Thoracic ultrasound (TUS) was then performed for all patients for signs suggestive of PE. Finally, MD-CTPA was performed to confirm or exclude the presence of PE. RESULTS: Patients were subdivided into two groups according to the result of MD-CTPA; group I (patients with PE) and group II (control group without PE). In our study, PE was present in the lower lobe in 75% of cases, then in the middle in 13% and in the upper lobe in 3.8% of cases. The majority of lesions in TUS were wedge-shaped lesions. No vascular flow was detected in 83% of PE-confirmed patients. The current study revealed that TUS has 81.25% sensitivity, 95% specificity, 98.3% positive predictive value, 77.2% negative predictive value and 87% accuracy in the diagnosis of PE. Univariate regression analysis revealed that the presence of wedge-shaped pleural-based lesions in grayscale US and the absence of flow signals by colour Doppler sonography (CDS) increase the possibility of PE. Wedge-shaped pleural-based lesions increase the possibility of PE by 1.48 times (P=0.0001), and the absence of flow signals by CDS increases the possibility of PE by 92.89 times (P=0.00001). Multivariate regression analysis revealed that adding absent flow signals by CDS to wedge-shaped pleural-based lesions by grayscale US increases the possibility of a PE diagnosis by 50.28 times (P=0.001). CONCLUSION: Chest ultrasound is a simple, safe, noninvasive, inexpensive, bedside diagnostic radiological technique that can be used in the emergency department for suspected PE or as an alternative to MD-CTPA when CTPA is contraindicated. Wedge-shaped lesions and the absence of flow signals by CDS increase the diagnostic value of ultrasound for PE.