Clinically, there can be various kinds of bleeding: 1. by bleeding site, there are cerebral bleeding, epistaxis, hemoptysis, vomiting blood, blood in stool, blood in urine, vaginal bleeding, subcutaneous bleeding and subarachnoid hemorrhage; 2. by bleeding degree, there are heavy bleeding, moderate bleeding and small bleeding; 3. by onset, there are acute bleeding and chronic bleeding; 4. by bleeding cause, there are trauma, surgery, tumor, congenital malformation, Infection causes, etc. 5.According to the blood vessel where bleeding occurs, it can be artery, vein or capillary. Acute hemorrhage is often life-threatening within a short period of time and requires emergency treatment. Common hemorrhages include: hemoptysis, vomiting blood, blood in stool, blood in urine, vaginal bleeding and subarachnoid hemorrhage. This type of bleeding is often difficult to control with medications, and surgical hemostasis is often difficult to perform because the patient is in hemorrhagic shock or the cause of the bleeding is unknown. In such cases, interventional treatment is the best choice: first, digital subtraction angiography, as the gold standard for the diagnosis of vascular lesions, can quickly and accurately identify the site of bleeding; and embolization of the target vessel for bleeding can immediately seal the bleeding rupture and achieve immediate hemostasis. At the same time, because interventional embolization is performed only under local anesthesia, without incision, patients are generally able to accept it. I. Hemoptysis: 9%-15% of respiratory diseases can cause hemoptysis, of which hemoptysis accounts for 1.5%, and the mortality rate is extremely high, reaching 60%-80%. Mainly hemorrhagic shock or death by asphyxiation due to large amounts of blood from the airways blocking the trachea. Hemoptysis of 200-300 mL or more in 24 hours is usually considered as hemoptysis. Significant impairment of oxygen exchange can occur when the volume of blood in the alveoli reaches 400 mL. The patient’s symptoms are closely related to the rate of bleeding, and hemoptysis can be considered when the patient develops life-threatening symptoms such as pallor, increased pulse, rapid breathing, decreased blood pressure and cyanosis, or when blood transfusions are required to maintain blood volume. There are about 100 causes of hemoptysis, with tuberculosis (38%), bronchiectasis (30%), bronchopulmonary carcinoma (9%), chronic lung inflammation and lung abscess (9%) being the most common, while pulmonary arterio-venous fistula, pulmonary embolism, pulmonary isolation, pulmonary trauma, congenital heart disease, mitral stenosis, pulmonary hypertension, bronchial aneurysm, bronchial artery-pulmonary artery fistula, and coagulation abnormalities are less less common. The first selective bronchial arteriography was successfully performed by Viamonle in 1963, and the first successful application of bronchial artery embolization to macrohemoptysis due to chronic inflammatory lesions of the lung was reported by Remy in 1974. The most common source of hemorrhage in hemoptysis is the bronchial artery, which accounts for more than 90% of the hemorrhage. The bronchial arteries are responsible for the blood supply to the bronchial wall, interstitial lung, pleura, pulmonary artery wall and part of the mediastinum. Whether chronic inflammatory process, fibrosis or tumor tissue growth, they can cause damage or erosion to the bronchus or interstitial lung, and once the affected bronchial artery branches rupture, hemoptysis or even hemoptysis can occur. The literature reports that the hemostasis rate of bronchial artery embolization for hemoptysis is 76.7%-96%, which shows that bronchial artery embolization is a reliable and effective method to stop hemorrhage in emergency. Currently, after decades of continuous development and improvement, this technique has become increasingly mature and has become the treatment of choice for hemoptysis in major hospitals. It is important to note that in about 5% of people there is traffic between the spinal artery and the intercostal artery, intercostal-bronchial artery trunk or bronchial artery; therefore, the most serious complication of bronchial artery embolization is spinal cord injury, with an incidence of about 0.4%-2.3%. When the segmental blood flow of the spinal cord is reduced by more than 50%, due to ischemia and hypoxia, transverse spinal cord injury manifestations may gradually appear, such as transient spinal cord pain, back discomfort, abdominal muscle contraction, muscle spasm of both lower limbs, weakness, and difficulty in urination. The severity and clinical manifestations depend mainly on the degree, speed and duration of ischemia and the vulnerability of neurons. To avoid this, it is necessary to make adequate preparation before surgery, use non-ionic contrast agent as much as possible during surgery, be familiar with vascular anatomy, avoid spinal artery branches during embolization, and prevent embolic agent reflux. Once symptoms of spinal cord injury appear, the catheter tip is first repositioned to reduce bronchial artery obstruction, while heparin and lidocaine are injected via the catheter to dilate the vessels and dissolve microthrombi. Postoperatively, mannitol is given for dehydration and cytarabine for nerve nutrition. The vast majority of patients can gradually recover from these treatments. Although bronchial artery embolization is an effective treatment for hemoptysis, it is still a palliative treatment and does not cure the primary disease such as bronchiectasis and tuberculosis. Therefore, when the bleeding is controlled and the condition is stable, active treatment of the primary disease is necessary. Gastrointestinal hemorrhage: Gastrointestinal hemorrhage is one of the common clinical emergencies, mainly manifested as vomiting blood, black stool or bloody stool, accounting for 1% of hospital emergencies, and its lethality is as high as 10%. Common causes include peptic ulcers, tumors, portal hypertension leading to bleeding esophageal varices in the fundus, acute gastric mucosal lesions, and peptic diverticula. In 1960, Nusbaum et al. first reported that selective angiography can determine the site of gastrointestinal bleeding, especially for vascular diseases such as gastrointestinal aneurysm, vascular malformation and intestinal vascular dysplasia, angiography is significantly better than other examinations. Not only can the site of bleeding be clearly identified, but also the nature and extent of the lesion, and the site of bleeding can be treated immediately and directly through the catheter. In 1972, Roesch successfully treated a patient with gastrointestinal bleeding by selective embolization of the gastroretinal artery via catheter. In recent years, DSA (digital subtraction angiography) examination of the GI tract and interventional treatment have become one of the clinically important diagnostic and therapeutic tools. The indications for interventional diagnosis and treatment of gastrointestinal bleeding include: 1. unexplained gastrointestinal bleeding, where the bleeding site cannot be clearly identified by fiberoptic gastroscopy. 2.Gastrointestinal bleeding caused by various reasons, and the conservative treatment by internal medicine is ineffective. 3.Acute gastrointestinal hemorrhage, clinical temporarily can not perform surgical procedures. 4.Biliary tract bleeding caused by liver injury due to surgical operation, interventional operation, percutaneous liver puncture and other medical factors. 5, cirrhotic portal hypertension leading to bleeding esophageal varices in the fundus of the stomach. Pelvic haemorrhage: Pelvic haemorrhage is commonly caused by pelvic trauma, fracture, pelvic tumor (including bladder, rectum and gynecological tumor) erosion of blood vessels, after pelvic surgery, after tumor radiotherapy, after delivery and other medical factors. In recent years, with the development of transportation, there has been an increase in car accident trauma; with the boom in construction, there has been an increase in fall from height injuries; and the increase in cesarean deliveries has led to an increase in postpartum hemorrhage. in 1972, Margulis first used internal iliac artery embolization to treat a case of arterial hemorrhage due to a pelvic fracture. Subsequently, it was rapidly accepted for its rapid hemostasis, safety, effectiveness, simplicity, and minimal trauma, and was successfully applied to pelvic haemorrhage due to various causes. The bleeding volume of pelvic haemorrhage is very large and often leads to rapid change in condition within a short period of time. According to statistics, 69% of the direct causes of pelvic fracture death are bleeding, and 30% die from acute renal insufficiency and sepsis caused by bleeding. Compared with traditional treatment, in interventional therapy, angiography not only can accurately find the bleeding site, but also can be super-selectively cannulated to directly embolize the bleeding artery, which should be the first choice for the following diseases: 1. pelvic haemorrhage caused by pelvic trauma and fracture. 2.Intrapelvic hemorrhage caused by benign tumor in the pelvis (such as uterine fibroids, etc.). 3.Pelvic bleeding caused by malignant tumor (such as bladder cancer, ovarian cancer, cervical cancer and rectal cancer, etc.), such as blood in urine, blood in stool and vaginal bleeding. 4.Postpartum hemorrhage caused by weak contractions, retained placenta, soft birth canal injury and postpartum infection. 5.Pelvic hemorrhage after surgery. 6.Intra-pelvic hemorrhage of unknown cause.