Which tympanogram finding is most consistent with middle-ear effusion?

• A. Type B flat
• B. Type A
• C. Type C
• D. Type As

Answer: (A)

A tympanogram measures how the tympanic membrane moves as air pressure changes in the ear. When a middle-ear effusion is present, fluid behind the eardrum dampens its movement so there’s little change in compliance across the pressure sweep. The resulting tracing is flat, with no distinct peak, which reflects the membrane and ossicles not moving normally because of the fluid. This flat pattern is the hallmark of fluid in the middle ear. By contrast, a normal, healthy middle ear shows a peak indicating good mobility, negative pressure with a peak shifted toward the negative side suggests eustachian tube dysfunction, and a reduced-peak pattern indicates a stiffer system. So the flat tympanogram best matches middle-ear effusion.