Microtympanometry, microscopy and tympanometry in evaluating middle ear effusion prior to myringotomy.

OBJECTIVE

To determine the accuracy of a hand-held microtympanometer (Microtymp, Welch Allyn) used by a general practitioner when compared with findings at myringotomy.

METHOD

Independent preoperative assessment of children's ears using microtympanometry by a general practitioner, microscopy and pneumatic otoscopy by a specialist otologist and impedance bridge tympanometry by a specialist audiologist were performed and compared with findings at myringotomy.

SUBJECTS

Fifty children (100 ears) on the waiting list for bilateral myringotomies and ventilation tube insertion for recurrent acute otitis media or otitis media with effusion.

RESULTS

Microscopy with pneumatic otoscopy had a 90.9% sensitivity and a 92.9% specificity in detecting middle ear effusions. Impedance bridge tympanometry had a 94.4% sensitivity and a 71.8% specificity if type B and C2 were combined to predict middle ear effusion. Microtympanometry had 100% sensitivity and 75% specificity if type B and C tympanograms were combined; if type B tympanograms alone were used, a sensitivity of 83.4% and specificity of 75% in predicting middle ear effusions was obtained.

CONCLUSION

The Microtypm is a useful instrument in general practice for assessment of middle ear effusions as no ears with fluid were missed in this study if type B and C tympanograms were considered abnormal. The Microtymp would also be useful as a screening instrument by suitably trained personnel.