Shifting dullness is the characteristic sign of
Hydropneumothorax is collection of both fluid(lower pa) and air(upper pa) in the pleural cavity.The hallmark diagnosis in hydropneumothorax is 3 'S':Shifting dullness(due to the presence of free fluid & air within the pleural cavity,dullness of fluid shifts from one place to other within chest with the change of posture of the patient),Succussion splash,and Straight fluid level(upper limit of dullness is horizontal).
Hydropneumothorax
Pneumothorax
Consolidation
Collapse
Respiratory system