This classification is related to the surgical treatment and complications of aneurysms, especially spinal cord ischemic injury.

Type I involves most of the descending aorta and proximal abdominal aorta, celiac trunk, superior mesenteric artery, and ends at the proximal renal arteries, accounting for 29% of thoracoabdominal aneurysms.

Type II involves the entire descending aorta and abdominal aorta and its visceral branches, accounting for 30%.

Type III involves the distal descending aorta and entire abdominal aorta and its visceral branches, accounting for 21%.

Type IV involves the abdominal aorta and its visceral branches, accounting for 20%.

Crawford classification does not clearly define the "distal descending aorta." Safi et al. used T6 as the anatomical marker for the upper and lower descending aorta based on Crawford classification, adding Type V thoracoabdominal aneurysm, which starts from the T6 intercostal level and involves the aorta above the renal arteries. Safi classification refines the content of Crawford classification.