What is congenital microtia? Congenital microtia is a birth defect of the auricle with an incidence of about 5.18 per million, and the incidence varies by country and region. The typical microtia is divided into three degrees: Grade 3 microtia presents with a bologna-like wrinkled or peanut-like appearance; Grade 2 microtia presents with a milder lesion that resembles a reduced model of a normal auricle, with some of the structures of the auricle missing; and Grade 1 microtia is a malformed ear with a smaller profile. The vast majority of microtia involves only one side, with the right side being more common than the left. The percentage of boys is double that of girls.