Otolaryngology Coding Alert

Question: What diagnosis code should I use for audiology tests? The notes read as follows:

Left pinna malformation with atretic meatus exists. We wish to rule out right hearing loss due to the problem with the left. Impression: 1) Normal right conductive mechanisms 2) Right acoustic emission and behavioral responses consistent with that seen in normal hearing children.
 
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Answer: Audiology tests are always bilateral.  Therefore, the diagnosis for the problem on the left side may be used, which is 744.29 (other specified anomaly of ear, including prominence of auricle and ridge ear).
 
If the ear with the malformation is not tested (which is highly unlikely), modifier -52 (reduced services) probably should be attached to the appropriate audiology CPT code, When one side has a hearing problem, it is very common for the other side to be tested.