Thrombosis is often secondary to: (1) portal venous congestion and depressed portal blood flow caused by hepatic steatosis or extrahepatic compression; (2) intra-abdominal purulent infections, such as gangrenous appendicitis, ulcerative colitis, strangulated hernia, etc.; (3) certain blood abnormalities, such as true erythrocytosis, hypercoagulable state caused by oral contraceptives; (4) injuries caused by trauma or surgery, such as mesenteric hematoma, splenectomy, right hemicolectomy, etc. What are the examination methods for portal vein blood flow depression caused by hepatic sclerosis or extrahepatic compression? 1.General fluoroscopy Fluoroscopy is simple and easy to perform, and the examination results can be obtained immediately, and the morphology and function of the organ can be observed at the same time. 2.Abdominal vascular ultrasound examination Abdominal vascular ultrasound examination of abdominal aortic aneurysm can measure the anterior-posterior diameter, long diameter and wide diameter of the aneurysm, which can be the preferred method for entrapped abdominal aortic aneurysm. Abdominal ultrasound is of great value for the diagnosis and differential diagnosis of inferior vena cava obstructive disease and the judgment of treatment effect. 3.Abdominal MRI examination MRI examination of the abdomen is an MRI examination of the abdomen, and for the neck and breast, MRI examination has considerable value. It is superior to CT in early demonstration of malignant tumors, invasion of blood vessels, and staging of tumors. There are often triggers of depressed portal blood flow, hypercoagulation, or vascular injury. The onset of disease is slow. It presents as abdominal discomfort, constipation, or diarrhea. After a few days or weeks, as the thrombus spreads and expands, the venous blood flow is obstructed, affecting the intestinal curvature, then sudden onset of severe abdominal pain, persistent vomiting, diarrhea and bloody stools are more common than arterial embolism. On physical examination, abdominal distension, abdominal pressure pain, rebound pain and abdominal muscle tension are seen. Bowel sounds are diminished or absent. Hemorrhagic fluid may be drawn by laparotomy. Fever and increased white blood cell count and red blood cell pressure are often present. Abdominal radiographs may show dilated and inflated affected small bowel with air-fluid planes. Intestinal peristalsis is absent on fluoroscopy.