Assessment of thoracic ultrasound in complementary diagnosis and in follow up of community-acquired pneumonia (cap)

Background: Chest X-ray (CXR) is the primary diagnostic tool for community-acquired pneumonia (CAP). Some authors recently proposed that thoracic ultrasound (TUS) could valuably flank or even reliably substitute CXR in the diagnosis and follow-up of CAP. We investigated the clinical utility of TUS in a large sample of patients with CAP, to challenge the hypothesis that it may be a substitute for CXR. Methods: Out of 645 consecutive patients with a CXR-confirmed CAP diagnosed in the emergency room of our hospital over a three-years period, 510 were subsequently admitted to our department of Internal Medicine. These patients were evaluated by TUS by a well-trained operator who was blinded of the initial diagnosis. TUS scans were performed both at admission and repeated at day 4-6th and 9-14th during stay. Results: TUS identified 375/510 (73.5%) of CXR-confirmed lesions, mostly located in posterior-basal or mid-thoracic areas of the lungs. Pleural effusion was detected in 26.9% of patients by CXR and in 30.4% by TUS. TUS documented the change in size of the consolidated areas as follows: 6.3 ± 3.4 cm at time 0, 2.5 ± 1.8 at 4-6 d, 0.9 ± 1.4 at 9-14 d. Out of the 12 patients with delayed CAP healing, 7 of them turned out to have lung cancer. Conclusions: TUS allowed to detect lung consolidations in over 70% of patients with CXR-confirmed CAP, but it gave false negative results in 26.5% of cases. Our longitudinal results confirm the role of TUS in the follow-up of detectable lesions. Thus, TUS should be regarded as a complementary and monitoring tool in pneumonia, instead of a primary imaging modality.