Surgeons are accustomed to categorizing the birth defects they treat surgically according to morphology rather than pathogenesis. Commonly used classification systems fail to take into account the cause or developmental pathology of a given structural defect. Furthermore, surgeons often select operative procedures without considering the evolution of specific defects. Dysmorphology is a fairly new discipline that seeks a better understanding of the cause and pathogenesis of birth defects, not only to ensure optimum treatment but also to encourage prevention of birth defects.