When evaluating a patient with acute glomerulonephritis, pulmonary-renal syndrome (PRS) is often on the differentials. PRS is used to describe a life-threatening condition characterized by the combination of rapidly progressive glomerulonephritis and diffuse alveolar hemorrhage (DAH). Common causes include anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis, anti-glomerular basement membrane (anti-GBM) disease and systemic lupus erythematosus.

The gold standard for diagnosing DAH is bronchoalveolar lavage, which is usually reserved for patients who have alternative reasons for pulmonary symptoms and signs. Imaging findings are non-specific but highly suggestive in the appropriate clinical context. Plain X-ray typically shows patchy or diffuse opacities; high-resolution thoracic CT scan characteristically shows diffuse ground glass or consolidative opacities bilaterally.

On lung ultrasound, DAH can look very similar to that of ARDS (acute respiratory distress syndrome) or viral pneumonia such as COVID-19. Click here for the previous post describing these findings in detail. Below are the images obtained from a patient with PRS in the setting of p-ANCA vasculitis (antibody titer 1:2560). Note thickened (>2-3 mm), irregular pleural line with hypoechoic subpleural areas likely corresponding to consolidations/hemorrhagic areas. Sliding appears to be reduced. Pleural line is better examined using a linear transducer in transverse plane. Diffuse B-line pattern is seen in the images obtained using a phased array transducer (with some spared areas). These B-lines do not seem to be homogeneous and appear more prominent at some places. CT image from the same patient shown.