Intestinal vascular malformation

　　First, etiology

　　The etiology and pathogenesis of this disease have not been fully understood, and it is prone to occur in the jejunum, cecum, and right half of the colon. Vascular malformations in children and young adults are more common in the jejunum and ileum, while in middle-aged and elderly individuals, they are more common in the colon, especially the right half of the colon. The main clinical manifestations of patients are gastrointestinal bleeding and secondary anemia.

　　Second, pathogenesis

　　Congenital arteriovenous malformations, whose pathological changes are the communication between submucosal arteries and veins, venous arteriogenesis, thickening, expansion, twisting, and hardening of the venous wall. They often occur in the rectum and sigmoid colon, often accompanied by cardiovascular diseases, peripheral vascular diseases, and aortic stenosis; acquired ones are secondary to certain diseases, such as portal hypertension, intestinal disease, degenerative changes of the submucosal venous wall in the elderly with chronic constipation, causing the submucosal veins running through the muscular layer of the intestinal wall to be repeatedly compressed due to muscle contraction, leading to increased intraluminal pressure in the veins, venous expansion, decreased function of the precapillary sphincter, direct communication between arteries and veins, and the formation of a functional arteriovenous fistula. Intestinal vascular malformations often occur simultaneously with colonic vascular malformations.

　　For gastrointestinal bleeding and secondary anemia. Gastrointestinal tumors, gastric cancer, small intestinal lymphoma, colorectal cancer, and other malformations of the gastrointestinal tract can also be manifested. Gastrointestinal polyps may only present with gastrointestinal bleeding without other clinical manifestations. Endoscopy and biopsy tissue, pathological examination, and X-ray barium meal examination can be used to differentiate from vascular malformations. The rectum and sigmoid colon are often accompanied by cardiovascular diseases, peripheral vascular diseases, aortic stenosis, and acquired ones are secondary to portal hypertension.

　　1, The course of the vascular lesion varies in length, with most being long-term, and some lasting for decades.

　　2, The bleeding patterns are diverse, including acute massive hemorrhage, intermittent hemorrhage, and chronic small hemorrhage.

　　3, Most hemorrhages are self-limiting or can be temporarily stopped by hemostatic drugs, blood transfusions, etc., and hemoglobin can also return to normal.

　　4, There are almost no positive symptoms and signs when not bleeding.

　　If an active bleeding focus can be found during surgery, the intestinal segment where the focus is located can be resected, and the bleeding can stop immediately. However, it is necessary to inspect all intestinal tracts carefully and comprehensively to avoid missing any. Even so, there have been reports of rebleeding after the focus is resected, which is often due to the fact that other foci have not bled and were not detected during surgery. The recurrence rate of bleeding after surgery in cases of intestinal vascular malformation is 7% to 90%, and the difference in recurrence rate after surgery is so large, which is related to whether the bleeding location is accurately located and whether the focus resection is thorough.

　　One, selective intestinal vascular angiography:

　　Since 1960, selective or high-selective angiography has been the main method for diagnosing the disease, with a diagnostic rate of 75% to 90%. Vascular malformations in angiography can be divided into 3 types: Type I is arteriovenous fistula or submucosal vascular maldevelopment; Type II is vascular hamartoma; Type III is hemorrhagic capillary telangiectasia (if caused by genetic factors, it is called hereditary hemorrhagic telangiectasia, also known as Osler-Weber-Rendu syndrome). The main signs after angiography include:

　　1, Abnormally increased vascular plexuses, with disordered structure.

　　2, Proliferation of terminal blood vessels, showing a spider-like expansion and tortuosity.

　　3, During the arterial phase, the veins show early opacification, presenting as a 'double track' sign, indicating the presence of shunting between arteries and veins.

　　4, During the hemorrhage phase, the contrast agent can be seen to溢出积聚在肠腔内.Extrude and accumulate in the intestinal lumen.

　　5, The venous phase shows venous expansion within the intestinal wall on one side of the mesenteric margin, which is tortuous.

　　Two, endoscopic examination

　　Since 1970, with the development of endoscopy and the improvement of operator skills, electronic gastroscopy, small bowel endoscopy, colonoscopy, and other endoscopic examinations have become the first choice for the diagnosis of vascular malformations. In recent years, capsule endoscopy has been developed, and the positive rate for the diagnosis of small intestinal vascular malformations can reach over 90%, but vascular malformations can be divided into:

　　1, Localized type (Type I):呈局限型血管扩张，与周围正常黏膜分界清楚，包括区域内的血管扩张(Ⅰa)和蜘蛛痣样血管扩张(Ⅰb).Vascular expansion is localized, clearly demarcated from the surrounding normal mucosa, including regional vascular expansion (Ⅰa) and spider nevus-like vascular expansion (Ⅰb).

　　2, Diffuse type (Type II):血管扩张呈弥漫性，范围广，色鲜红，与正常黏膜分界较模糊.Vascular expansion is diffuse, with a wide range, bright red color, and less clear demarcation from the normal mucosa.

　　3, Hemangioma-like type (Type III):呈紫红色或灰蓝色团块，稍隆起于黏膜面，与周围正常黏膜分界清楚.Purple or blue-gray masses, slightly elevated on the mucosal surface, clearly demarcated from the surrounding normal mucosa.

　　Three, radionuclide imaging

　　Radionuclide imaging using 99mTc-labeled red blood cells for radioactive nuclide scanning is relatively sensitive for the localization diagnosis of active hemorrhage caused by intestinal vascular malformation, but it cannot make a definitive diagnosis and can only be used as an auxiliary method for angiography and endoscopic diagnosis.

　　Four, surgical exploration

　　The intestinal vascular malformation hemorrhage has both diagnostic and therapeutic effects. It is proposed that patients under 50 years old with recurrent hemorrhage should undergo surgery as soon as possible, and intraoperative endoscopy and/or intraoperative angiography can be used to help locate the lesion.

　　Diet should include foods rich in protein, such as lean meat, beef, mushrooms, jujube, sesame, etc. In addition, foods for the prevention and treatment of deficiency syndromes include black fungus, yam, coriander, chive, eggplant, euryale, lotus root, fennel, lychee, chicken, lamb, fig, etc.

　　I. Treatment

　　Vascular malformations without symptoms do not require treatment. For patients with bleeding, routine treatment is the same as that for upper and lower gastrointestinal bleeding. In addition, endoscopic treatment, surgical treatment, catheter treatment, and hormonal therapy can also be performed.

　　1. Endoscopic treatment can be performed by endoscopic coagulation, laser, and injection of sclerosing agents for lesions accessible to the endoscope.

　　2. Surgical treatment is only suitable for patients with bleeding who have failed multiple endoscopic treatments and for patients with massive bleeding that endangers life. It should be avoided to perform blind surgical treatment, as the incidence of rebleeding after surgery has not decreased.

　　3. Catheter treatment is based on the discovery of the focus through angiography, and the drug (such as posterior pituitary hormone, terlipressin, thrombin or tranexamic acid, etc.) is infused through the catheter and the gelatin sponge is cut into small pieces of about 2mm and mixed with the contrast agent, then injected into the feeding artery of the lesion through the catheter to achieve hemostasis. However, complications such as intestinal ischemia and intestinal necrosis may occur, so a cautious attitude should be held towards the vascular embolism of the intestine. If it is the terminal branch vessel, embolization therapy should be禁忌.

　　4. Hormonal therapy Recently, some scholars have applied estrogen-progesterone therapy to treat intestinal vascular malformation and bleeding, achieving certain efficacy, but the mechanism is not yet fully understood. Electron microscopy studies have shown that estrogen can restore the integrity of abnormal vascular endothelial cells; in addition, it may also have certain improvements on the microcirculatory state and coagulation mechanism.

　　II. Prognosis

　　If an active bleeding focus can be found during surgery, the intestinal segment where the focus is located can be resected, and the bleeding can stop immediately. However, it is necessary to inspect all intestinal tracts carefully and comprehensively to avoid missing any. Even so, there have been reports of rebleeding after the focus is resected, which is often due to the fact that other foci have not bled and were not detected during surgery. The recurrence rate of bleeding after surgery in cases of intestinal vascular malformation is 7% to 90%, and the difference in recurrence rate after surgery is so large, which is related to whether the bleeding location is accurately located and whether the focus resection is thorough.