Abdominal aortic aneurysm, which is an arterial dilatation disease, is the most common type of aneurysm. In recent years, the incidence of abdominal aortic aneurysm in China has shown an increasing trend. Some statistics show that the incidence of abdominal aortic aneurysm is about 8.8% in elderly people over 65 years old. Moreover, there are many patients who will have sudden aneurysm rupture without any symptoms, and the mortality rate of such aneurysm rupture can be more than 90%. Therefore, the medical profession also calls abdominal aortic aneurysm a “time bomb” in the human body. So, how do abdominal aortic aneurysms form? Atherosclerosis is the most common and major cause of abdominal aortic aneurysms. When atherosclerosis occurs in the arterial vessels, the local wall of the artery thickens, causing an impairment of the nutrient supply to the vessel, and the endothelium of the artery then undergoes degenerative changes, resulting in abdominal aortic aneurysm. There is also a portion of abdominal aortic aneurysms that are confined bulges of the arterial wall caused by trauma, infection, and other causes. Abdominal aortic aneurysms can occur in all parts of the abdominal aorta. Clinically, abdominal aortic aneurysms are usually divided into two categories using the level of the renal artery as the boundary: those below the level of the renal artery, which may involve one or both of the patient’s iliac arteries; and those above the level of the renal artery, which are also called thoracoabdominal aortic aneurysms, which often involve the arteries supplying the patient’s abdominal organs. Abdominal aortic aneurysms are unlikely to heal on their own, and if left untreated, they can easily rupture and bleed, leading to death. Therefore, clarifying the clinical manifestations of abdominal aortic aneurysm is the key to early diagnosis of the disease. The clinical manifestations of the disease include: 1. A pulsatile mass in the abdomen. Most patients can find a pulsating mass around the umbilicus and in the left mid-upper abdomen, and the pulsation has a multidirectional swelling, accompanied by tremor and vascular murmurs. 2. Pain. Most patients only have mild discomfort or distension in the abdomen, but when the tumor erodes into the vertebral body or compresses the spinal nerve roots, there will be obvious pain in the low back. If severe abdominal pain or low back pain suddenly appears, it is a sign that the tumor has involved the blood supplying artery in the abdominal cavity or caused rupture and bleeding of the retroperitoneal vessels. 3. Compression of adjacent organs. If the tumor compresses the duodenum and proximal jejunum, it may cause gastrointestinal symptoms; if it compresses the ureter, it may lead to urinary tract obstruction; and a few patients may have obstructive jaundice because the tumor compresses the common bile duct. 4.Arterial embolism. If the thrombus inside the aneurysm cavity is dislodged, it can cause acute embolism of abdominal aortic branches, such as mesenteric artery embolism and lower limb artery embolism, and even cause ischemic necrosis of the corresponding parts. 5. Aneurysm rupture. This is the most dangerous symptom for patients with abdominal aortic aneurysm. Rupture of the aneurysm can lead to massive bleeding, and such patients often die of hemorrhagic shock within a short period of time. If a patient is suspected of having an abdominal aortic aneurysm, imaging tests such as ultrasonography, abdominal aortography or digital subtraction angiography (DSA), and CT can help confirm the diagnosis, and they can also determine the size and extent of the aneurysm, the presence of atherosclerosis and attached thrombus in the wall, and the relationship between the aneurysm and its surrounding organs. Ultrasonography is particularly useful for the early diagnosis of abdominal aortic aneurysms below the level of the renal artery. When a patient is diagnosed with an abdominal aortic aneurysm, he or she should be treated aggressively, and the only effective way to treat the disease is to perform surgery. In principle, patients with abdominal aortic aneurysms should undergo elective surgery, but those who do not tolerate surgery well should first be actively treated with medication in order to improve the patient’s physical condition and create favorable conditions for surgery. However, for those whose aneurysm ruptures, immediate surgery is required. In addition, the ability to rupture an abdominal aortic aneurysm is directly related to the size of the diameter of the aneurysm. Studies have shown that the incidence of rupture is 10% when the diameter of the aneurysm is less than 4 cm, and 30% to 50% when the diameter of the aneurysm is greater than 5 cm and less than 10 cm. If the diameter of the tumor is larger than 1O cm, the incidence of rupture is 80%. Therefore, a tumor with a diameter of 5 cm is currently used as a uniform clinical standard for performing surgical treatment. However, even if the aneurysm is small, there is a risk of acute rupture. Therefore, patients with abdominal aortic aneurysms should still undergo surgery as early as possible. Patients with small aneurysms should have regular imaging examinations (e.g., ultrasound), and if there is a tendency for the aneurysm to increase in size, surgery should be performed to prevent serious consequences.