Does everyone with any grade of microtia have hearing loss? also should they have their hearing tested regularly and should they all have an abr test?

No, not always: Microtia refers to abnormalities of the external ear, and not a direct cause of hearing loss. However, hearing loss can be associated with microtia, particularly if atresia (an absence of the ear canal) is present. Regular hearing tests are a good place to start. An abr may not be necessary. Early identification of hearing loss is always important, particularly if both ears are involved.

Essentially yes: A baseline hearing test is recommended and if abnormal an MRI or abr may be necessary. Annual screenings of hearing loss especially if there is some evidence of hearing loss is often times recommended. An evaluation with an ENT doctor is the first step.