Spectral gradient acoustic reflectometer (SGAR) is a technology to assist in the detection of middle ear fluid occurring in the context of diagnosing acute otitis media (AOM) and otitis media with effusion (OME). The technology involves sending a harmless, inaudible sonar-like sound wave from the emitter that goes through the tympanic membrane, hits the posterior wall of the middle ear space, and bounces back to the sound detector in the device. If there is only air in the middle ear space, the sound wave bounces back quickly, and you get a high reading. If the sound wave bounces back more slowly, there is middle ear effusion. The thicker the effusion, the more likely it is pus and an AOM or a chronic OME (depending on the clinical situation), causing the sound wave to bounce back more slowly and giving a low reading.
The specificity of a high reading is remarkable at around 95%, so a high reading is a big reassurance that middle ear effusion is absent. A lower reading suggests effusion and the lower it is, the greater the sensitivity. When I get an unexpected higher or lower reading, I go back and reexamine the patient.
Dr. Michael E. Pichichero
I asked our nurses to compare the handheld tympanometer to the SGAR. They actually perform the testing, and I interpret it. The nurses said:
• The SGAR is easier to use because of how quickly a readout is obtained.
• If a child is crying or moving, they can still get a readout.
• You don’t have to change the tip of the SGAR for the size of the external ear canal.
• The SGAR is easier to read than the tympanometer.
• The SGAR is easier to interpret for the parents.
• You don’t have to get a seal with the ear canal with SGAR, as you do with a tympanometer.
• The SGAR uses a disposable tip.
I asked our office manager to look up our use of the SGAR and tympanometer during our everyday practice. We found that SGAR or tympanometry was used in 12% of patient encounters in which the diagnosis of AOM or OME was part of the chief complaint. The ratio of use was 3:1, favoring SGAR. The most frequent use was in 30% of patient encounters tied to the diagnosis of "otalgia" (388.70) because with that diagnosis, we are stating to parents and patients that there is no middle ear pathology seen on exam, and it is confirmed by a test using sonar waves with the SGAR device. Our nurse practitioners and physician assistants particularly find the use of the SGAR beneficial in helping to reassure the parents and patients that they have not missed an AOM or OME.
The billing code is the same for SGAR and tympanometry (92567), so the fee payment is the same for both tests. Our second most common use is in association with possible AOM (382.9) at 12% of visits. Third is OME (381.02) used in a follow-up visit to determine the presence and thickness of persisting effusion.
About one-quarter of children seen in our practice with a chief complaint of "earache" receive the diagnosis of otalgia, often confirmed by SGAR, and do not receive an antibiotic. Thus, they are offsetting the charge for the procedure by saving on the costs of antibiotics and the accumulation of excessive diagnoses of AOM and OME leading to ear tube surgeries and tonsillectomy/adenoidectomy. The diagnosis of AOM and OME requires a middle ear effusion to be accurate, and only SGAR measures detection of middle ear effusion. SGAR is a must own device for clinicians who exam ears. SGAR can help in conjunction with otoscopy for a difficult diagnosis of AOM. If I am having troubleremoving wax, or if the external ear canal is particularly curved, or if I’m on the fence or the parent seems to need further evidence of my diagnosis, I turn to the SGAR. If I can get a reading, then it can really help, and my nurses are successful in getting a reading about 90% of the time. The main issue is ear canal wax, because occlusion by wax of more than 50% of the external ear canal opening causes invalid readings.
We should prescribe antibiotics for AOM in my opinion, but not for otalgia and not if the diagnosis is uncertain. The SGAR device when properly used can help to reduce unnecessary use of antibiotics and their complications. In prior "ID Consult" columns, I have discussed improving the diagnostic accuracy of AOM and OME. Performing a good otoscopic exam with the best tools available and combining that exam with SGAR or tympanometry, in selected cases, is the best practice in my opinion, and what I do in my own practice.