Mesenteric venous embolism

　　Superior mesenteric vein thrombosis accounts for 5% to 15% of all mesenteric vascular ischemic diseases. The disease has relatively concealed clinical manifestations. Diagnosis is often delayed, and most cases are diagnosed only when laparotomy is performed. Superior mesenteric vein thrombosis can be divided into primary and secondary types. The etiology is clear for secondary thrombosis, accounting for the majority, such as tumors, intra-abdominal inflammation, postoperative cirrhosis, and portal hypertension. The proportion of those taking oral contraceptives among young female patients with superior mesenteric vein thrombosis is 9% to 18%. The etiology is unknown for primary thrombosis, and the most common cause is a hypercoagulable state caused by hereditary or acquired diseases.

　　There is faint bloody fluid in the abdomen, and hospitals with conditions can use laparoscopy to observe the blood supply of the intestinal tubes and the distribution of the mesentery under direct vision. ④If this disease is considered, pay attention to searching for the cause, whether there are genetic factors, the patient has hypertension, coronary heart disease, myocardial infarction, lower limb phlebitis, lower limb deep vein thrombosis, abdominal tumor, pancreatitis, surgical history, etc.

　　Thrombosis often occurs secondary to: ①Hepatic cirrhosis or extrinsic compression causing portal hypertension and blood stasis; ②Intra-abdominal suppurative infection, such as gangrenous appendicitis, ulcerative colitis, strangulated hernia, etc.; ③Certain blood abnormalities, such as polycythemia vera, a hypercoagulable state caused by oral contraceptives; ④Injuries or surgical injuries caused by trauma or surgery, such as mesenteric hematoma, splenectomy, right hemicolectomy, etc. About 1/4 of the patients have no obvious predisposing factors and are called primary mesenteric vein thrombosis.

　　After the formation of thrombosis, it can continue to spread towards the proximal and distal ends. When the venous return of the involved intestinal loops is completely blocked, the intestinal tubes become congested and edematous, with pinpoint hemorrhage under the serosa, which then spreads into patches. The intestinal wall and mesentery become thickened and edematous. Subsequently, hemorrhagic infarction occurs in the intestinal loops, presenting a dark purple color.

　　A large amount of bloody fluid exudes from the intestinal wall and mesentery into the intestinal lumen and peritoneal cavity. The acute occlusion of veins can also reflexively cause vasoconstriction and thrombosis of visceral arteries, accelerating the process of intestinal necrosis. Finally, it also leads to hypovolemia, infection, and toxic shock.

　　Abdominal pain, characterized by colicky nature, nausea, decreased appetite, and vomiting, the clinical manifestations of superior mesenteric vein thrombosis can be divided into acute, subacute, and chronic three types. Acute cases have an abrupt onset and quickly develop peritonitis and intestinal necrosis. Subacute refers to those patients with persistent abdominal pain for several days or weeks without intestinal necrosis.

　　Chronic mesenteric venous thrombosis is actually a prehepatic portal hypertension, the focus of its treatment is on the management of portal hypertension complications such as variceal bleeding and ascites, and intestinal ischemia is not the key to treatment. Most patients present with a subacute process without intestinal necrosis or variceal bleeding. However, some patients may develop intestinal necrosis after a long time of abdominal pain, so the so-called acute and subacute manifestations cannot be completely separated. Regardless of arterial or venous thrombosis, the clinical manifestations of mesenteric vascular ischemia are inconsistent with physical examination findings, such as abdominal pain. The pain from mesenteric venous thrombosis is usually located in the middle abdomen and is of colicky nature, indicating that the lesion originates from the small intestine. The duration of symptoms varies greatly, with more than 75% of patients presenting with symptoms lasting more than 2 days. Nausea, decreased appetite, and vomiting are common. 15% of patients have hematemesis, melena, or black stools, and nearly 1/2 of patients have positive occult blood tests in the stool.

　　Due to the relatively low incidence and non-specific symptoms, diagnosis is often delayed. The initial physical examination can be completely normal. In the later stages of the disease, fever, abdominal muscle tension, and rebound pain may appear, indicating the occurrence of intestinal necrosis. About 1/3 to 2/3 of patients have signs of peritonitis. The渗出 from the intestinal lumen or peritoneal cavity can lead to a decrease in blood volume and circulatory dynamics instability, systolic blood pressure

　　①There is no obvious reason for anorexia and nausea;

　　②Abdominal distension, abdominal dull pain and discomfort, with a persistent and progressive trend, sometimes with relief, but the pain increases after relief;

　　③Abdominal signs and symptoms do not match, there is no fixed tenderness point;

　　④Bowel sounds can be hyperactive, or they can be diminished;

　　⑤White blood cell and platelet counts are elevated;

　　⑥General antispasmodics and analgesics are ineffective.

　　Preoperative diagnosis is still difficult, and angiography is of little value. The main focus is on the prevention and treatment of diseases that cause thrombosis. It is often diagnosed during laparotomy due to acute intestinal obstruction complicated by peritonitis. Thrombectomy can be performed, and if there is intestinal necrosis, it is necessary to perform intestinal resection at the same time, carry out effective prevention and treatment, and avoid the further development of the disease to occur MVT.

　　Prevention is also necessary after childbirth. Postpartum venous thrombosis is a disease that is prone to occur in puerperae during the postpartum period, especially in the first week after childbirth, which is the peak period for thrombosis. Generally speaking, venous thrombosis is most common in the lower extremities, but it can also occur in the portal vein, mesenteric vein, renal vein, ovarian vein, and pulmonary vein, etc.

　　One of the main obstacles to the prevention strategy of thrombosis is the concern about bleeding complications. However, a large number of meta-analyses and placebo-controlled, double-blind, randomized clinical studies have confirmed that low-dose unfractionated heparin (LDUH), low molecular weight heparin (LMWH), or vitamin K antagonists (VKA) at preventive doses almost do not increase the risk of bleeding complications of clinical significance. There is also increasing evidence for new anticoagulants such as pentasaccharide. There is good evidence that adopting the correct preventive strategy can achieve ideal risk/benefit and cost-effectiveness. The prevention strategy for thrombosis can not only improve the prognosis of patients but also reduce the total hospitalization costs.

　　After the diagnosis of this disease, in addition to gastrointestinal decompression, blood volume supplementation, and the use of broad-spectrum antibiotics, anticoagulation therapy should be carried out. At the same time, the changes in abdominal signs should be closely observed. In case of suspected intestinal necrosis, an immediate laparotomy should be performed to remove the necrotic intestinal tract along with the entire mesentery containing the venous thrombus, in order to prevent the spread of thrombus and affect other intestinal tracts. Postoperative anticoagulation therapy should continue for 6 to 8 weeks.

　　There have been multiple venous thromboembolic diseases, so you may need long-term anticoagulation and combined antiplatelet prevention of venous and arterial thromboembolic diseases (pay attention to the INR range when taking warfarin). If there are symptoms such as leg swelling and weakness, you can take blood circulation capsules, Dai奥斯明 tablets, etc., especially in summer. It is recommended to follow up regularly on the status of the whole body arteries and veins, and to have a systematic evaluation every year.

　　During physical examination, abdominal distension, abdominal tenderness, rebound tenderness, and abdominal muscle tension can be observed. Bowel sounds are weakened or absent. Abdominal puncture can draw blood-containing fluid. There are often fever, increased white blood cell count, and hematocrit. Abdominal X-ray films can show dilated and aerated involved small intestine with air-fluid levels. During fluoroscopy, intestinal peristalsis disappears. Usually, blood tests are not helpful for the diagnosis of superior mesenteric vein thrombosis, but metabolic acidosis and increased serum lactate levels can be used to determine the presence of intestinal necrosis, but they are often manifestations of late-stage disease.

　　Laboratory examination shows a significant increase in white blood cell count. There are signs of blood concentration and metabolic acidosis.

　　Abdominal X-ray films show mild or moderate distension and bloating of the large and small intestines. In the late stage, due to a large amount of fluid accumulation in the intestinal lumen and abdominal cavity, the abdominal density is generally increased. 50% to 75% of patients have normal abdominal X-ray films, and only 5% of patients show special signs of intestinal ischemia: the appearance of finger pressure sign indicates intestinal mucosal ischemia, intestinal wall emphysema, or free air in the portal vein are characteristic manifestations of intestinal infarction caused by mesenteric vein thrombosis.

　　Abdominal color Doppler ultrasound examination can detect mesenteric vein thrombosis, but for cases suspected of having mesenteric vein thrombosis, computerized tomography (CT) should be chosen.

　　CT examination can provide a diagnosis for 90% of patients, but the accuracy of diagnosis for small thrombi in the early portal vein decreases.

　　Selective mesenteric angiography can show thrombi located in large veins or delayed contrast enhancement of the superior mesenteric vein.

　　Magnetic resonance imaging has high sensitivity and specificity for diagnosing superior mesenteric vein thrombosis, but its examination process is relatively complex and has poor popularity. With the advancement of technology, magnetic resonance imaging may occupy a place in the diagnostic methods for superior mesenteric vein thrombosis.

　　Patients with mesenteric venous thrombosis may have serous hemorrhagic ascites. In this case, diagnostic paracentesis may be helpful for diagnosis. The pneumoperitoneum procedure during laparoscopy may increase intraperitoneal pressure and reduce mesenteric blood flow, so it should be avoided. Since the colon and duodenum are rarely involved, the value of colonoscopy and gastroenteroscopy is limited. Endoscopic ultrasound can detect mesenteric venous thrombosis, but due to intestinal distension during the examination, it is best used for patients without acute symptoms.

　　For cases of mesenteric superior venous thrombosis, CTA is a good examination method, which can not only show mesenteric vessels and determine the range of involved intestinal segments but also exclude other diseases that cause abdominal pain. Mesenteric angiography should be used for patients suspected of having a tendency to thrombosis, as thrombosis often occurs in smaller vessels within the mesenteric venous system.

　　1. It is recommended to eat more watermelons because they not only have the effects of clearing heat and detoxifying but also diuretic and hypotensive effects, rich in a large amount of sugar, vitamins, and proteases, and are very helpful for patients with mesenteric superior venous thrombosis.

　　2 It is recommended to eat more potassium-rich foods such as kelp and bran, as they can significantly reduce blood lipids and anticoagulant effects. Mushrooms, onions, and garlic are also helpful for the recovery from this disease. In addition, avoid drinking stimulants such as coffee and strong tea before going to bed.

　　3 In addition, during this period, fluid or semi-fluid light foods, so I often make delicious congee for patients to drink, such as lean meat congee and egg congee are quite good choices! It is禁忌 eating hard, salty, and spicy foods that may damage and irritate the oral mucosa.

　　4 It is recommended to eat more foods rich in vitamins and proteins, such as fruits, vegetables, lean meat, milk, etc., and avoid eating overly fatty foods to prevent increasing blood viscosity and aggravating the condition.

　　Finally, for long-distance travel, it is advisable to drink plenty of water, reduce alcohol consumption, and dilute the blood; do not wear corsets or tight clothing, and wear elastic stockings to prevent poor blood flow; avoid long periods of sleep, and move around more, even if sitting, should often massage the lower limbs to promote blood circulation. For patients who have been lying in bed for a long time, family members should strengthen their passive limb movements. Pregnant and postpartum women should pay attention to reasonable exercise, and if possible, they can refer to the practice of foreign pregnant women wearing anti-thrombosis stockings. In summary, high-risk groups should enhance their preventive awareness and be prepared for emergencies.

　　The treatment of this disease includes the treatment of the primary disease and symptomatic treatment. Patients with portal hypertension can undergo splenectomy or shunt surgery. The treatment for mesenteric venous thrombosis includes anticoagulant therapy and anticoagulant combined surgical treatment. For patients with acute or subacute mesenteric ischemia, heparin therapy should be started immediately upon diagnosis. Not all patients with mesenteric venous thrombosis require surgical exploration, but those with definite signs of peritonitis should undergo emergency surgery.

　　If the diagnosis of mesenteric vein thrombosis during surgery is confirmed, anticoagulation therapy should be started immediately.

　　Due to the lack of a clear boundary between ischemic intestinal segments and normal intestinal segments, emphasizing obtaining a normal intestinal segment for resection may lead to the resection of too much viable intestinal tissue. Therefore, the attitude towards intestinal resection for this disease should be more cautious, with the principle of preserving as much viable intestinal tissue as possible.

　　To avoid resecting too much potentially viable intestinal tissue, it is best to adopt a secondary exploration method 24 hours later. Secondary exploration is particularly suitable for patients with extensive involved intestinal segments and a certain amount of mesenteric blood flow. In some cases, it is also possible to choose to perform conservative intestinal resection without primary anastomosis of the intestinal segment, and instead, pull the distal end out through an abdominal wall stoma, using the stoma as a window to observe the viability of the intestinal segment, which can allow some patients with poor conditions to avoid secondary exploration.

　　In rare cases, if the thrombosis formation time is short and limited to the superior mesenteric vein, thrombectomy can be performed. Thrombosis with a more extensive range is not suitable for thrombectomy. Arterial spasm is a common condition, and it can be avoided by using a combined approach of intravascular opium injection, anticoagulation, and secondary exploration to prevent the resection of ischemic intestinal segments that may recover.

　　If intestinal necrosis does not occur, membranous vein thrombosis can be treated without surgery but with medication. However, there are currently no indicators that can accurately indicate the risk of patient intestinal necrosis. For patients without peritonitis or perforation, intravenous antibiotic treatment is not required. However, immediate heparin anticoagulation therapy at an early stage of the disease can significantly improve patient survival rates and reduce recurrence rates, even if it is applied during surgery. The initial treatment of systemic heparin can be given as a 5,000U intravenous injection, followed by continuous infusion to maintain the activated partial thromboplastin time at more than twice the normal level. Even if there is gastrointestinal bleeding, if the risk of intestinal necrosis is greater than the risk of gastrointestinal bleeding, anticoagulation therapy can be given.