Mesenteric venous thrombosis a rare but lethal form of mesenteric ischemia.
Estimated incidence 2.7 per 100.000 patient years.
An insidious disease with a high mortality rate typically attributed to the long delay in diagnosis.
The superior mesenteric vein follows the arterial circulation.
The superior mesenteric vein drains the bowel from the second portion of the duodenum to approximately the right two-thirds of the transverse colon.
The superior mesenteric vein joins the splenic vein posterior to the neck of the pancreas to form the portal vein.
Mesenteric vein thrombosis is an important cause of intestinal ischemia.
MVT responsible for up to 15% of all mesenteric ischemic events.
The left gastric vein drains the lower half of the esophagus and the upper half of the lesser curve of the stomach and enters at the formation of the portal vein.
The fundus of the stomach is drained by the short gastric veins and enters the splenic vein.
The inferior mesenteric vein drains the left colon and enters into the splenic vein.
Rapid diagnosis and expedient surgery is efficacious.
CT angiography of abdomen/pelvis with intravenous contrast highly sensitive and specific up to 93% and 96%, respectively, for diagnosis.
One of many causes of mesenteric ischemia.
Superior MVT impairs venous return from the bowel, with venous engorgement and ischemia.
Complete occlusion of mesenteric veins can result in transmural bowel infarction, if there is insufficient time for the development of collateral circulation.
Treated patients have a good prognosis, with long-term anticoagulant therapy.
Accounts for approximately 10-15% of all cases of mesenteric ischemia.
Accounts for 0.006% of hospital admissions.
Found in approximately 0.001% of patients who undergo exploratory laparotomy.
Risk increases in patients with hypercoagulable states such as polycythemia rubra vera, protein C deficiency, visceral infection, portal hypertension, perforated viscus, blunt abdominal trauma, malignancy, previous abdominal surgery, pancreatitis and in smokers.
Patients on oral contraceptives are also at increased risk of venous thrombosis.
Patients who have undergone splenectomy, colectomy, and Roux-en-Y gastric bypass are at increased risk of subsequent portal venous thrombosis.
Cancer may cause thrombosis because of a hypercoagulable state or by direct extension of the tumor.
Prevalence is higher in cirrhotic patients, probally due to turbulent venous bloodflow, and increased tendency for thrombosis.
MVT is reported in approximately 15% of patients awaiting liver transplantation.
The most common cause seems to be intra-abdominal sepsis.
Most commonly associated with thrombophilia or local intraabdominal infections.
No underlying cause is found in 25-50% of patients diagnosed with mesenteric venous thrombosis.
Mesenteric venous system carries 30% of cardiac output.
May be associated with portal vein thrombosis.
The venous system, for the most part, parallels the arterial system.
The superior mesenteric vein is formed by the jejunal, ileal, ileocolic, right colic, and middle colic veins, which drain the small intestine, cecum, ascending colon, and transverse colon.
The right gastroepiploic vein drains the stomach into the superior mesenteric vein.
The inferior pancreaticoduodenal vein drains the pancreas and duodenum.
The inferior mesenteric vein drains the descending colon, the sigmoid colon, and the rectum through the left colic vein, the sigmoid branches, and the superior rectal vein, respectively.
Inferior mesennteric vein thrombosis represents only 0-11% of cases of mesenteric venous thrombosis.
The inferior mesenteric vein joins the splenic vein, which then joins the superior mesenteric vein to form the portal vein, which enters the liver.
Thrombosis of the mesenteric vein results in bowel wall edema which decreases outflow of arterial blood flow of the mesenteric artery and causes bowel ischemia.
Mortality related to the development of colonic ischemia and to the development of the short bowel syndrome.
Patients usually present with insidious onset of symptoms described as vague abdominal discomfort that typically evolve over 7-10 days.
Abdominal pain is the most common symptom in acute mesenteric venous thrombosis.
In chronic mesenteric venous thrombosis.patients present with portal hypertension and esophageal varices.
Patients may have a distended abdomen and guaiac-positive stools.
Paracentesis may demonstrate bloody peritoneal fluid, a late sign of bowel ischemia.
Laboratory studies help to suggest diagnosis and include: CBC, prothrombin time, activated partial thromboplastin time, chemistries and evaluation for thrombophilia.
Abdominal CT and angiography confirm the diagnosis of acute venous occlusion.
Abdominal CT scan considered to be the diagnostic test of choice.
The diagnosis of venous thrombosis is usually confirmed during laparotomy or autopsy.
After a hypercoagulable state has been excluded the patient be considered to have idiopathic venous thrombosis.
Anticoagulation is the initial approach to therapy.
Indications for surgery in patients with acute mesenteric venous thrombosis include signs of peritonitis, bowel perforation, possible bowel infarction, and hemodynamic instability.
Surgery includes bowel resection.
With chronic mesenteric venous thrombosis management is aimed at reducing complications of portal hypertension.
In the presence of bowel infarction, acute mesenteric thrombosis is a surgical emergency and should be treated emergently.
After stabilization long-term anticoagulants indicated.