Acoustic reflectometry in the detection of middle ear effusion

Acoustic reflectometry, a new technique for detecting middle ear effusion, was compared with results from tympanocentesis or myringotomy in 75 patients (141 ears). There was a highly significant association (P less than .0001) for ears having middle ear effusion with high reflectivity (5 through 9 units) and for ears having no middle ear effusion with low reflectivity (0 through 4 units). In a pediatric population with middle ear effusion present in 98 of 141 ears and using reflectivity readings greater than 4 to indicate middle ear effusion, the sensitivity of this technique was 86.7% and the specificity was 69.8%. False-positive errors usually occurred in ears with thick tympanic membranes, or in ears in which reflectivity was determined prior to the induction of anesthesia. False-negative errors usually occurred in ears with both air and fluid. This technique was validated by direct comparison with tympanocentesis or myringotomy and can be used with pneumatic otoscopy and impedance tympanometry to follow children with middle ear effusion.