ID Consult

Improving diagnosis of otitis media


 

The diagnosis of otitis media absolutely requires visualization of the tympanic membrane. So it may be time to upgrade your tools to do a better job in diagnosing. Think about how often you use your otoscope. Are you using the best available technology, or are you using the otoscope you got in medical school, perhaps quite a few years ago? It may be time for an upgrade. Considering how often you might use an otoscope, you can afford it. You deserve it.

The improved features of new otoscopes include remarkably better illumination. The quality of the light not only has to do with the lumens, but also the color of the light. Also there is a version of an otoscope called a Macro View (Welch Allyn, Skaneateles Falls, N.Y.). It allows you to increase the magnification on the tympanic membrane (TM) as needed. There is an option to purchase a lighter and smaller handle for the scope, and that can improve ease of use for persons with small hands.

For all otoscopes, the bulb should be replaced when illumination begins to fade and you cannot get back the intensity of light with a battery recharge. For most primary care practitioners, bulbs usually require replacement annually.

Speculum size is key to getting the most light onto the TM; the bigger the speculum, the better. Advancing the speculum as far into the external ear canal as you can without causing discomfort helps improve the intensity of the light shone on the TM. While it is convenient to use disposable specula, they are not as good as reusable ones because the finish on the inside of disposable specula is duller than on reusable specula, thus decreasing the amount of light shone on the TM. Also, disposable specula often are too short, and that too reduces the light shone on the TM.

Many clinicians have not been trained on using pneumatic otoscopy, or even if trained, they find it inconvenient and/or problematic to use because it requires a seal of the speculum against the external auditory canal; this makes children cry. The problem is that you really need to use pneumatic otoscopy in some cases to determine if the TM is retracted (no acute infection) or bulging (acute infection, or AOM). I use pneumatic otoscopy in about one-third of cases, and to this day I am surprised sometimes when the negative pressure pulls a retracted TM forward when I was pretty sure the TM more likely was bulging. There are specula with a semisoft sleeve midway down the shaft, but I have not found they are any less likely to cause the child to cry, because as anyone knows who has stuck a Q-tip swab into their ear canal, it is sensitive skin.

Then there is the wax! Clinical studies show that about half of children have wax in their external auditory canal blocking 25% of the view, and one-quarter have wax blocking 50% of the view. The best tool I have found to clear the wax is a plastic cerumen spoon (called a safe ear curette) made by Bionix Medical Technologies (Toledo, Ohio). I use the white ones as they are the most flexible. Ninety percent of the time I can scoop the wax out of the way and get a good view. For the remaining difficult cases, the ear canal needs to be irrigated with warm water (code 69210), and then the remaining wax can be scooped out.

Tympanometry (code 92567) is another tool to aid in accurate diagnosis and follow-up of otitis media. A key aspect of the diagnostic algorithm advocated by the American Academy of Pediatrics is a determination of whether the TM is bulging (AOM) or not (no AOM). A retracted TM is inconsistent with the diagnosis of AOM. Tympanometry requires a seal with the external auditory canal because a pressure is applied to the TM to determine TM movement. After positive and negative pressure are applied by the instrument, the readout will be a positive peaked curve (bulging), a negative peaked curve (retracted), a normal peaked curve (normal), or flat, no curve (stiff TM).

The first three readouts are very helpful in distinguishing AOM from no AOM. The flat curve indicates three possibilities: The TM is stiff, perhaps due to thickening; the TM is not moving because the middle ear space is filled with pus behind it, meaning it is AOM; or the TM is not moving because the middle ear space is filled with effusion fluid behind it, meaning the patient has otitis media with effusion. In the case of a flat readout, the tie breaker should come from the visual exam and/or the use of spectral gradient acoustic reflectometry (code 92567).

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