Acute suppurative otitis media, an infection of the middle ear. In this view along the external ear canal, the posterior part of the eardrum (tympanic membrane) is bulging (at left) & there are two bullae (blisters) on the lower parts of the membrane (the dark purple areas at bottom of the image). Otitis media occurs as a sequel to viral or bacterial infection of the upper respiratory tract spreading up the eustachian tube into the middle ear. The subsequent blockage of the eustachian tube results in a build-up of fluid & pus; the increased pressure distorts & may perforate the eardrum, causing temporary deafness.