Central and lateral abdominal wall defects are probably distinct and likely arise from different pathogenetic mechanisms. An autopsy study was done using data from a total of 45 central and lateral abdominal wall defect cases to evaluate if they are indeed separate entities and to suggest possible mechanisms involved in their formation. Central defects were found to be statistically different from lateral defects; malformations that co-existed with central defects were mainly bilateral and internal and also involved "inferior" organs in relation to fetal-embryonal blood flow. Patients with lateral defects were more often female, and their coexistent defects were usually unilateral and external, with only 1 defect occurring in an "inferior" organ. These results indicate mechanisms of a vascular perfusion deficit for the majority of the central defects and of external disruption for the lateral defects.