Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A large retrocardiac opacity with an air - fluid level represents a large hernia containing stomach and transverse colon . The hernia has minimally increased in size since ___ . The aortic knob is calcified . Left upper lobe opacity most likely represents atelectasis due to mass effect from the hernia . Vascular congestion has slightly increased since ___ . There is no pulmonary edema , pleural effusion or pneumothorax .
    OUTPUT:
    
Large hernia containing stomach and transverse colon . Left upper lobe atelectasis likely from mass effect . Vascular congestion slightly increased since ___ . No overt pulmonary edema .