China’s famous geologist Li Siguang and the great physicist Albert Einstein both passed away due to ruptured abdominal aortic aneurysms. Although abdominal aortic aneurysm is not a tumor and is not as scary as cancer. However, a ruptured abdominal aortic aneurysm is more dangerous than a malignant tumor. Readers must have many questions in their mind: what kind of disease is abdominal aortic aneurysm? What are its clinical manifestations? Why is it so dangerous? Is there any good way to detect an aneurysm before it ruptures? Can an aneurysm be effectively treated before it ruptures? An aneurysm is a permanent abnormal expansion of an artery formed after localized weakness. It is caused by atherosclerosis, infection, necrosis of the middle layer of the artery, or congenital factors that cause the arterial wall structure to lose its normal integrity, and rupture when it expands and deforms to the limit like a balloon under the effect of intra-arterial blood pressure, resulting in instantaneous hemorrhage and death. With the arrival of aging population and the change of diet structure, the incidence of aneurysm, especially abdominal aortic aneurysm, is on the rise in China. Statistics show that the incidence of abdominal aortic aneurysm is about 8.8% among people over 65 years old. Many patients suddenly rupture the aneurysm without any symptoms and die of hemorrhage, with a mortality rate of more than 90%. Therefore, the medical profession refers to aneurysm as a “time bomb” in the body. Abdominal aorta is the largest artery in the human body. Abdominal aortic aneurysm is a limited bulging of the arterial wall caused by lesions and damages, and it is not a tumor in the usual sense. Abdominal aortic aneurysm can be divided into: ① true aneurysm: atherosclerosis is the main factor, due to the deposition of lipids in the arterial wall, the formation of atheromatous plaques and calcium deposits, so that the artery loses its elasticity, in the impact of the pressure of the blood flow, the aneurysm body is progressively increasing, most of them are pike-shaped. ② Pseudoaneurysm: caused by trauma, direct or indirect violence (such as shrapnel, puncture), penetrating trauma rupture of the artery, dissection, surrounded by soft tissue and the formation of a pulsatile hematoma, the surrounding fibrous tissue to become the wall of the aneurysm, mostly in the form of a capsule. (iii) Clip aneurysm: cystic necrosis or progressive degenerative lesion in the middle layer of the artery, which may be related to old age, specific inflammation, metabolic abnormalities, and so on, and is a systemic lesion. Abdominal aortic aneurysms are unlikely to heal on their own and often rupture and bleed easily leading to patient death if left untreated. Therefore, clarifying the clinical manifestations of abdominal aortic aneurysm is the key to early diagnosis of the disease. The clinical manifestations of the disease mainly include: ① The appearance of pulsatile mass in the abdomen. Most patients can find a pulsating mass around the umbilicus and the left middle and upper abdomen, and its pulsation has a multidirectional swelling feeling, which can be accompanied by tremor and vascular murmur at the same time. Pain. Most patients only have mild abdominal discomfort or distension, but when the tumor erodes into the vertebral body or compresses the spinal nerve root, there will be obvious low back pain. If severe abdominal pain or low back pain occurs suddenly, it is a sign that the tumor has involved the blood-supplying arteries in the abdominal cavity or caused rupture and bleeding of retroperitoneal vessels. (iii) Compression of neighboring organs. When the tumor presses the duodenum and proximal jejunum, it can cause digestive symptoms; when it presses the ureter, it can lead to urinary tract obstruction; there are also a few patients with obstructive jaundice due to the compression of the tumor on the common bile duct. ④Arterial embolism. If the thrombus in the cavity of the aneurysm is dislodged, it can cause acute embolism of the branches of the abdominal aorta, such as mesenteric artery embolism, lower limb artery embolism, and even cause ischemic necrosis of the corresponding parts. ⑤ Aneurysm rupture. This is the most dangerous symptom in patients with abdominal aortic aneurysm. Rupture of the aneurysm will lead to massive bleeding, and such patients often die of hemorrhagic shock in a short period of time. The wall of the vessel in the aneurysm lumen has an irregular geometric shape and varies in thickness, and the blood flow becomes swirling and slow, often accompanied by thrombus formation. Formation of thrombus adheres to the wall, sometimes the base is mechanized, known as attached wall thrombus. Sometimes the thrombus is dislodged and easily produces arterial embolism. In addition, the aneurysm can also be secondary to infection. Once an infection occurs, symptoms worsen and the aneurysm is more likely to rupture. How to rule out a “time bomb” early? When an aneurysm is suspected, a non-invasive color Doppler ultrasound is performed to detect the size of the aneurysm and the presence of atherosclerosis and thrombus in the wall of the aneurysm. This test is particularly useful for early detection of abdominal aortic aneurysms below the renal arteries. Abdominal aortography or digital subtraction angiography (DSA) and CT can help in diagnosis and differentiation, and in determining the size and extent of the aneurysm, as well as in ruling out disease in other organs. Abdominal aortic aneurysms cannot be cured with medications, and surgery is the only effective treatment for aneurysms. When is the best time to operate? Domestic literature reports that the rate of rupture increases significantly when the maximum diameter of the aneurysm is greater than 4 centimeters. Therefore, 5 cm is currently used as a uniform standard for surgical intervention. However, acute rupture is also possible even in smaller tumors. Whether an abdominal aortic aneurysm ruptures is directly related to the size of the tumor diameter. Studies have shown that the incidence of rupture is 10% for diameters less than 4 centimeters, 30%-50% for diameters greater than 5 centimeters, and 80% for diameters greater than 10 centimeters. There is disagreement as to whether intraluminal adnexal thrombus increases the risk of rupture. If thrombosis is detected, thrombolytic agents should be used early in order to achieve a reduction in complications caused by thrombus dislodgement. Traditional abdominal aortic aneurysm surgery is performed with general anesthesia, a large incision in the middle of the abdomen, placing the large and small intestines aside, and then removing the aneurysm and reconstructing the blood vessels through the retroperitoneum. It is already a high-risk surgery when no rupture occurs, and if rupture occurs in the event of hemorrhage and shock, it is conceivable that the surgery will be more difficult and complicated. This surgical method is highly traumatizing and has a long recovery time.