Prediction of serous versus purulent otitis media by otoscopy and tympanometry in an animal model.

Non-invasive methods for distinguishing different types of otitis media would have clinical value in predicting otologic morbidity. Two such methods, otoscopy and tympanometry, were used in two experimental models of otitis media to determine whether there are unique otoscopic and tympanometric characteristics of serous and purulent otitis media. A flat (type B or B+) tympanogram and yellow tympanic membrane each had a high likelihood of predicting middle ear effusion in these models, and the best prediction was obtained using both parameters simultaneously. A yellow tympanic membrane color predicted purulent otitis media in one model but did not distinguish purulent from serous ears in the other model. In one model, serous otitis media was frequently associated with a type C (negative pressure) tympanogram. Tympanometry provided a valuable adjunct to otoscopy in detecting effusion and in distinguishing serous and purulent disease. These observations may apply to otitis media in humans, although the variable etiologies of otitis media in humans may confound the ability of otoscopy and tympanometry to distinguish middle ear effusion types.