Study for evaluation of using transthoracic lung ultrasound in diagnosis of pulmonary embolism

Background: As pulmonary embolism (PE) could be fatal, its early diagnosis is crucial. Its diagnosis depending on pre-test probability necessitates a combination of clinical, laboratory, and imaging data. Aim: To determine the reliability of lung ultrasound (LUS) in diagnosis of PE in hemodynamically stable patients. Methodology: In this prospective clinical study, 30 hemodynamically stable patients (19 men, 11 women, age 22-70 years) with suspected PE and moderate to high clinical probability on Wells score were investigated using LUS by a pulmonologist. PE was confirmed if at least a single hypoperfused (by color doppler imaging), hypoechoic, round or wedge-shaped pleural based consolidation was detected with or without pleural effusion,(figure1). Final diagnosis was made by CT pulmonary angiography (CTPA) (reference method). Results: PE was diagnosed in 18 patients. LUS was found true positive in 11 patients, false positive in 1 patient, true negative in 11 patients, false negative in 7 patients. Sensitivity, specificity, positive predictive value, negative predictive value was 61%, 91.6%, 91.6%, 61% respectively. Conclusion: LUS is a reliable diagnostic method in clinically stable patients with moderate to high suspicion for PE when used with color doppler imaging. Although, a negative LUS study cannot rule out PE with certainty, but positive findings may decrease the current abuse of CTPA with unnecessary contrast exposure.