There are two classification systems used to describe thoracic aortic dissections:

The DeBakey classification:

Type I: Dissection originating in the ascending aorta extending a variable length frequently into the aortic arch and/or descending thoracic aorta

Type II: Dissection originating in the ascending aorta remaining confined to this area.

Type III: Dissection originating in the descending thoracic aorta. This is further classified as IIIa which is confined to the thoracic aorta and IIIb which extends to the abdominal aorta.

The Stanford classification:

Type A: Dissection involving any part of the ascending aorta

Type B: Dissection remaining confined to the descending thoracic aorta