According to the extent of aneurysm involvement, Ahn and Blum proposed different typing methods according to the length of the proximal neck of AAA and the extent of distal involvement of the aneurysm, and Thurnher proposed the Siegfried typing according to the relationship between AAA and renal artery. Schumacher’s typing In 1995, Schumacher et al. divided AAA into three main types according to the impact of aneurysm morphology and aneurysm on clinical decision making, among which, type II was divided into type IIA, IIB and IIC according to the different branches involved in AAA. Type I: proximal aneurysm neck length ≥ 1.5 cm, distal aneurysm neck length ≥ 1.0 cm; Type IIA: proximal aneurysm neck length ≥ 1.5 cm, AAA involvement of aortic bifurcation; Type IIB: proximal aneurysm neck length ≥ 1.5 cm, AAA involvement of distal common iliac artery; Type IIC: proximal aneurysm neck length ≥ 1.5 cm, AAA involvement of distal common iliac artery bifurcation; Type III: proximal aneurysm neck length < 1.5 cm In addition to the proposed staging, the study also pointed out that type I AAA patients are suitable for repair with a straight vascular stent; type II patients can be repaired with a "Y" vascular stent, and type IIC patients need to reconstruct the internal iliac artery on one side to provide blood supply to the pelvic organs and gluteal muscles while performing endovascular repair; type III patients are contraindicated for endovascular luminal repair because the AAA is at a short distance from the renal artery and the stent vessel will affect the renal artery blood supply. 2. Ahn typing In 1997, Ahn et al. divided AAA into four types according to the clinical needs of endovascular luminal treatment, among which, type II was further divided into type IIA and IIB according to the different branches involved in AAA. Type I: proximal neck length ≥1.5 cm, distal neck length ≥1.0 cm; Type IIA: proximal neck length ≥1.5 cm, distal neck length <1.0 cm, and the tumor does not significantly involve the common iliac artery; Type IIB: proximal neck length ≥1.5 cm, and the tumor is distally involved or connected to the common iliac artery; Type III: proximal neck length <1.5 cm, distal neck length ≥1.0 cm; Type IV: proximal neck length <1.5 cm, distal neck length ≥1.0 cm Type IV: proximal neck length <1.5 cm, distal neck length <1.0 cm, and the aneurysm does not obviously involve the common iliac artery. Among them, type I AAA patients are suitable for repair with straight stent vessels; type IIA and type IIB patients can be repaired with "Y" stent vessels; type III and type IV AAA are contraindicated for endoluminal treatment. In addition, because of the lateral expansion of AAA along the abdominal aorta, the neck of the aneurysm and the aneurysm are easily twisted into an angle. The angulation range is less than 120°. AAA grading has an important reference value in intracavitary repair. Type A: AAA distal and proximal aneurysm neck length >10mm, aneurysm diameter <25mm, no involvement of common iliac artery; Type B: AAA proximal aneurysm neck length >10mm, aneurysm diameter <25mm, internal diameter of common iliac artery on one side <12mm, aneurysm involvement of aortic branches; Type C: AAA proximal aneurysm neck length >10mm, aneurysm diameter <25mm, aneurysm involvement of common iliac artery and branches, and aneurysm involvement of common iliac artery. Type D: AAA involving internal iliac artery bilaterally; Type E: AAA with proximal neck length <10 mm and aneurysm diameter ≥25 mm. Thurnher proposed the Siegfried typing, which is now widely used in open surgery. Suprarenal type: AAA involving the opening of the renal artery or above; renal type: AAA located within 15mm below the renal artery; infrarenal type: AAA located more than 15mm below the renal artery.