[Epidemiology and risk factors for microtia in Colombia]

Microtia is a major malformation of the auricle, comprising a clinical spectrum ranging from a slight reduction in the size of the auricle or one of its parts to the complete absence of the pinna (anotia). Its prevalence varies according to the region of the world it is evaluated in. We analyzed a range of maternal, neonatal, and familial variables in a case group and a control group, and compared them with the existing literature.

We collected information from the Latin-American Collaborative Study on Congenital Malformations (ECLAMC) gathered between 2001 and 2006, where we found 27 cases of isolated microtia; we also collected information from 103 control subjects. Data were analyzed using Student's t and odds ratio (OR).

Microtia distribution was 3 (11.1%) patients with grade I microtia, 19 (70.4%) with grade II microtia, 2 (7.4%) with grade III microtia. We found no patients with anotia. Regarding laterality, the right side was involved more often. Male-to-female ratio was 1.7:1. Birthweight pound 2,500 g produces an OR of 3.25 (95% CI, 1.11-9.58) for the development of microtia.

Microtia may be directly or indirectly associated with the early onset of labour. Future studies should include long-term follow up of the patients in order to detect possible anomalies of the oculo-auriculo-vertebral spectrum. It is also important to take anthropometric measurements to increase the likelihood of detecting cases of grade I microtia and mid-face hypoplasia, and to define with greater accuracy whether isolated microtia is the mildest form of the oculo-auriculo-vertebral syndrome.