This condition affects all major structures within the thorax and abdomen.

  • The heart is located on the right side of the thorax, the stomach and spleen on the right side of the abdomen, and the liver and gallbladder on the left side of the abdomen. 
  • The left lung and the right lung are switched, and blood vessels, nerves, lymphatics, and the intestines are also transposed.  

Situs Inversus is generally an autosomal recessive genetic condition, found in identical "mirror" twins. One slight difference in anatomy is that normally the left lung is smaller than the right lung in order to accommodate the heart. 

Source of Picture: http://www.myhealthyfeeling.com/situs-inversus-dextrocardia-situs-solitus/ 

The differences in anatomy, the normal body placement of figure A compared to the reversal placement of figure B.