When the diagnosis of otitis media has been made on the basis of skilled clinical observation and the tympanic membrane is intact, it is practical to assume that an effusion is present. However, this can be confirmed only by recovery of fluid from the middle ear on tympanocentesis or myringotomy. Several methods will confirm the diagnosis of effusion with the indicated accuracy, as generally reported in the literature (Table 1).
Acute Otitis Media
A common error in the diagnosis of otitis media with effusion (OME) is equating an "injected" or "red" eardrum with OME. Acute otitis media may present with an injected drum, but the critical factor is not drum color but the presence of fluid in the middle ear cavity. The drum frequently is suffused and red when an infant or toddler is crying from either fear or pain during the otoscopic examination. A bulging eardrum, on the other hand, usually is regarded as defining acute otitis media (also called suppurative or purulent otitis media) with or without symptoms (pain, sleeplessness, fever, irritability) of systemic illness.
Experienced clinicians try to avoid the "red ear" error with either tympanometry or acoustic reflectivity (Table 1) or by careful removal of all external ear contents to visualize fully the landmarks (eg, both ends of the malleolus) and their mobility with the pneumatic otoscope.