Heterotaxy syndrome (situs ambiguous) is a disturbance in the usual left-right distribution of the thoracoabdominal organs. Unlike situs inversus, heterotaxy does not entirely translate into a complete mirror image. This syndrome can be disturbed into one of two subsets:

1. heterotaxy with isomerism of the right atrial appendages (asplenia syndrome)

2. heterotaxy with isomerism of the left atrial appendages (polysplenia syndrome)