Disease Information for Mesenteric vein thrombosis: Definition

Mesenteric venous thrombosis (also known as visceral venous thrombosis) is a rare but lethal form of mesenteric ischemia; Antonio Hodgson first described mesenteric ischemia in the latter part of the 15th century; In 1895,

Elliot first described mesenteric venous thrombosis as a cause of mesenteric ischemia; By the turn of the 19th century, many review articles and texts were describing the recent advances in the characterization and treatment of mesenteric ischemia, particularly venous thrombosis; In 1935, Warren and Eberhard reported that intestinal infarction resulted from ischemia due to venous thrombosis, and they reported a mortality rate of 34% in patients with venous thrombosis after resection; Unfortunately, this mortality rate still holds despite improvements in therapy; Problem: Mesenteric venous thrombosis is an insidious disease with a high mortality rate typically attributed to the long delay in diagnosis; Patients with this condition benefit from rapid diagnosis and expedient surgical therapy; Mesenteric venous thrombosis is one of many causes of mesenteric ischemia, and the mechanism has been well described; Once treated, patients with this condition have a fairly good prognosis, and long-term outcomes are good if patients receive long-term anticoagulant therapy; Frequency: Mesenteric venous thrombosis accounts for approximately 10-15% of all cases of mesenteric ischemia; This accounts for 0; 006% of hospital admissions, and venous thrombosis is found in approximately 0; 001% of patients who undergo exploratory laparotomy; Etiology: The risk of acute mesenteric venous thrombosis increases in patients with hypercoagulable states (eg, polycythemia vera, protein C and S deficiencies), visceral infection, portal hypertension, perforated viscus, blunt abdominal trauma, malignancy, previous abdominal surgery (open or laparoscopic), or pancreatitis and in patients who smoke; Women taking oral contraceptives are also at increased risk of venous thrombosis; Patients who have undergone splenectomy, colectomy, and Roux-Y gastric bypass are at increased risk of subsequent portal venous thrombosis, which rarely results in bowel infarction; Malignancy may cause thrombosis because of a hypercoagulable state or by direct extension of the tumor; The most common cause seems to be intra-abdominal sepsis; No underlying cause is found in 25-50% of patients diagnosed with mesenteric venous thrombosis; Pathophysiology: While the mesenteric arterial system may carry 25-40% of the cardiac output at one time, the venous system typically carries 30%; The mechanism that causes ischemia is a massive influx of fluid into the bowel wall and lumen, resulting in systemic hypovolemia and hemoconcentration; Resulting bowel edema and decreased outflow of blood secondary to venous thrombosis impede the inflow of arterial blood, which leads to bowel ischemia; While bowel ischemia is detrimental to the patient, the resulting multiple organ system failure actually accounts for the increased mortality rate; Clinical: Patients with mesenteric venous thrombosis have an insidious onset of symptoms described as vague abdominal discomfort that typically evolve over 7-10 days; Patients may have a condition that predisposes them to a hypercoagulable state, which may be elicited by taking a thorough history; Cancer, polycythemia vera, or a history of deep vein thrombosis or pulmonary embolus are important risk factors that should be elicited from the history; Patients presenting with pancreatitis or signs of intra-abdominal infection should be considered predisposed to developing mesenteric venous thrombosis;

Patients may have a distended abdomen and guaiac-positive stool samples; If the patient has an underlying intra-abdominal infection, peritoneal signs may be elicited and a palpable abdominal mass may be felt; As with acute mesenteric ischemia, patients may report pain disproportionate to that normally elicited during a physical examination;

Paracentesis may demonstrate bloody peritoneal fluid; however, this occurs after bowel infarction and, therefore, is a late sign; Unfortunately, laboratory examinations are not much help for confirming the diagnosis of venous thrombosis; Laboratory studies help more to suggest, rather than exclude, the diagnosis; Requisite laboratory studies include prothrombin time (PT), activated partial thromboplastin time (aPTT), CBC count (which may reveal leukocytosis and/or hemoconcentration), and chemistries (which may show metabolic acidosis); Leukocytosis and acidosis are the most specific laboratory findings in patients with ischemia; -------------------[Emedicine website 2007]--------------------

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