Mesenteric vein thrombosis is an invisible killer threatening human health because of its lack of specificity and relatively insidious clinical manifestations, and the diagnosis is often delayed, and the definitive diagnosis is only obtained in most cases during open exploration, thus the mortality rate is high.
I. Etiology
Superior mesenteric vein thrombosis is associated with hemodynamic abnormalities, hypercoagulable state and vascular wall damage. It can be divided into primary and secondary according to its causes. Those with clear etiology are called secondary, while those with unknown etiology are called primary or idiopathic. Secondary superior mesenteric vein thrombosis has multiple triggers: thrombophlebitis, visceral inflammatory disease, post-abdominal surgery, liver disease (cirrhosis), portal hypertension, malignancy, heart disease, congestive splenomegaly, oral contraceptives, hematological disorders, constipation, diabetes, trauma, and ectopic pregnancy. With the increased ability to diagnose hereditary coagulation disorders and to identify hypercoagulable states, the proportion of idiopathic cases in this disease is gradually decreasing, and now about 75% of mesenteric vein thrombosis can be diagnosed etiologically. The most common causes are hypercoagulable states resulting from hereditary or acquired diseases, such as malignancy, abdominal inflammation, post-surgery, liver cirrhosis and portal hypertension. Those using oral contraceptives account for 9% to 18% of young women with superior mesenteric vein embolism.
II. Clinical manifestations
Lack of specific clinical manifestations, the main symptoms are
1, abdominal pain. Intermittent or persistent abdominal cramps that are difficult to locate and difficult to be relieved by antispasmodic or analgesic drugs, and the clinical symptoms do not match the signs are the characteristics of the disease.
2. nausea and vomiting are frequent concomitant symptoms.
3, vomiting blood or blood in the stool, black stools
4, fever and peritonitis. For the middle and late manifestations, once appeared, suggesting the possibility of intestinal necrosis.
5, other. Acidosis, anemia and shock may occur in the late stage. There may be abdominal distension, muscle tension, active bowel sounds, and ascites signs in case of intestinal necrosis.
Third, the auxiliary examination
1, abdominal plain film examination: only 5% of patients show special signs of intestinal ischemia: the presence of acupressure signs in the intestinal lumen suggests intestinal mucosal ischemia, and intestinal wall emphysema or free gas in the portal vein is a characteristic manifestation of intestinal infarction caused by mesenteric vein thrombosis.
2.Abdominal color Doppler ultrasonography: mesenteric vein thrombosis can be detected, but CT examination should be further selected for cases suspected of mesenteric vein thrombosis.
3.Enhanced CT examination of abdomen: it can make the diagnosis in more than 90% of patients, which can not only show the mesenteric vessels and determine the scope of the involved intestinal canal, but also exclude other diseases that cause abdominal pain.
4.Selective mesenteric angiography: It can show thrombus located in large veins or delayed visualization of the superior mesenteric veins.
5.MRI examination: It has high sensitivity and specificity for the diagnosis of superior mesenteric vein thrombosis, but its examination procedure is more complicated.
Diagnosis
Superior mesenteric vein thrombosis is mostly subacute in onset, and because of its atypical clinical manifestations, it is difficult to make a clear diagnosis in most cases before surgery or before death. Therefore, for patients with acute abdomen who present with clinical symptoms and severe abdominal pain without obvious signs, this disease should be considered and early diagnosis is possible by performing enhanced abdominal CT examination.
V. Treatment
Preoperative general treatment includes gastrointestinal decompression, fluid replacement, correction of dehydration, correction of acidosis, and transfusion of blood for anemia and shock should be given. There is less agreement on the use of antibiotics, but prophylactic application is advocated in view of the disruption of the intestinal mucosal barrier.
In patients with acute or subacute superior mesenteric vein thrombosis, heparin therapy should be started as soon as the diagnosis is made.
1. Surgical approach.
After the early diagnosis, early superior mesenteric vein dissection for thrombosis + continuous thrombolysis with pump placement in portal vein (or right gastroretinal vein) can remove the fresh thrombus in superior mesenteric vein and portal vein trunk, while continuous pumping of thrombolytic drugs such as urokinase or recombinant fibrinogen activator during and after portal vein placement can dissolve some tiny thrombus, which can improve the efficacy of thrombosis and avoid extensive small bowel necrosis This can improve the efficacy of embolization, avoid extensive small bowel necrosis, preserve as much small bowel as possible, and avoid short bowel syndrome. At present, the Department of Vascular Surgery of Peking University Hospital has saved the lives of a large number of patients with superior mesenteric vein thrombosis through this method.
2.Postoperative anticoagulation therapy.
The anticoagulant is low-molecular heparin as the first choice, and the oral anticoagulant warfarin is added for more than 3 months to maintain the international standardized ratio INR between 2~2.5. For those with hereditary disorders and chronic hypercoagulable blood, lifelong warfarin is required.