A pulsatile mass is palpable in the abdomen with the same rhythm as the heart rate, accompanied by vague abdominal pain. Examination: a throbbing mass can be palpated in the midline of the abdomen, shuttle shape, unable to move, with deep pressure pain; blowing-like murmur can be heard on auscultation. If the abdominal pain is sudden or intensified, it often suggests that the tumor may rupture. If the rupture is small and in the posterior wall, retroperitoneal hematoma can be formed, and the bleeding can be stopped automatically after compression; if the rupture enters into the abdominal cavity, hemorrhagic shock can occur, and the patient can die if no timely operation is performed. If the tumor ruptures into the abdominal cavity, hemorrhagic shock may occur, and the patient may die if timely surgery is not performed. Sometimes, the tumor ruptures into the retroperitoneal space, resulting in swelling of the waist and hypochondrium and subcutaneous petechiae. Sometimes the tumor ruptures into the intestine, abdominal aortic-intestinal fistula can be formed, and gastrointestinal hemorrhage and shock can occur; individual tumor ruptures into the inferior vena cava to form abdominal aortic-inferior vena cava fistula, and the patient can have right heart hypertension, and in severe cases, it can be followed by right heart failure. According to the clinical manifestations of abdominal aortic aneurysm, combined with auxiliary examinations such as ultrasound, CT, MRI and abdominal aortography, the diagnosis can be clearly defined. Auxiliary examination can not only clarify whether the abdominal aortic aneurysm is suprarenal or infrarenal; but also clarify the size and scope of the abdominal aortic aneurysm and whether it is accompanied by iliac artery lesions, which can provide a reliable basis for the choice of treatment. Etiology and pathology Abdominal aortic aneurysm is the most common type of aneurysm. The incidence rate is getting higher and higher, and the condition is so dangerous that it can lead to death if not treated in time. Generally, patients do not have obvious clinical symptoms, and they are often found in physical examination or abdominal surgery, especially in ultrasound examination. Some emaciated patients can sometimes feel a pulsatile abdominal mass on their own. Individuals may sometimes have abdominal pain, mostly located around the umbilicus or in the mid-upper abdomen. Its etiology is not yet completely clear, but it is known to be mostly related to atherosclerosis, which is more than 95% in western developed countries and about 70% in China. It can also be caused by infection, melphalan, trauma, tuberculosis, leukoaraiosis or congenital dysplasia, etc. Marfan syndrome, polyarteritis and Ehlers-Danlos syndrome can also complicate this disease. Abdominal aortic aneurysm can occur the following pathological changes and consequences: 1, aneurysm rupture The wall of the aneurysm is often irregular, varying in thickness, and there is often calcification or atheromatous plaques, and the blood passes through the relatively narrow lumen to the enlarged body of the aneurysm, and the jet-like blood flow becomes a vortex. According to Laplace’s law, the more the artery expands, the greater the pressure on its wall. In this way, the long-term repeated effect, the tumor is progressive increase, in addition to aggravate the pain and pressure and other symptoms, due to the continuous impact of the blood flow, and ultimately inevitable in the weak point of the tumor body penetration, causing serious bleeding; 2, aneurysm attached wall thrombosis, the lumen of the tumor due to the rough wall and the slow flow of blood, often with wall thrombus. The wall thrombus can sometimes be dislodged and produce arterial embolism at the distal end of the aneurysm. Occasionally, a wall thrombus may completely block the aneurysmal lumen, usually only in the peripheral arteries. In the case of atherosclerosis of the arterial endothelium, the shedding of atheromatous plaques and the outflow of semi-liquid cholesterol-like substances from the aneurysm cavity may also cause distal arterial embolism. 3. Secondary infection Aneurysms may also be infected, which may be characterized by a sudden increase in the severity of the symptoms, accompanied by inflammation. Aneurysm in the infection and distal arterial embolism is often easy to accelerate the rupture of the basis; 4, the formation of the tumor wall of the sandwich hematoma The wall of the tumor due to the role of eddy current, the force of the impact of the blood flow to withstand the obvious increase, often make the endothelium or the middle layer of the rupture, separation of the formation of a sandwich aneurysm-like hematoma. At this time, the tumor may rapidly increase in size, and the symptoms are aggravated.