Situs ambiguus

Situs ambiguus or situs ambiguous (the former spelling is more correct etymologically, but the latter spelling is very common), also known as heterotaxy or heterotaxia, is a rare congenital defect in which the major visceral organs are distributed abnormally within the chest and abdomen. Heterotaxy in general refers to any defect of left-right laterality and arrangement of the visceral organs. This includes the congenital defect situs inversus, which results when arrangement of the organs in the abdomen and chest are mirrored, so the positions are opposite the normal placement. Situs inversus is the mirror image of situs solitus, which is normal asymmetric distribution of the abdominothoracic visceral organs. Patient's with situs ambiguous are considered isomeric in that they have organs with 2-right-sides or 2-left-sides, most commonly observed in relation to the atria of the heart.