Interventional Radiology, Surat

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MESENTERIC VENOUS THROMBOSIS (MVT)

MVT refers to a blood clot that blocks off (occludes) the mesenteric vein, which is located in the tissue that connects the intestine to the back of the abdominal wall.

Incidence and Prevalence:

MVT is a rare but often lethal form of intestinal ischemia and makes up 5% to 15% of all cases of acute mesenteric ischemia.

While the true prevalence is unknown, the incidence of symptomatic mesenteric thrombosis is reported to be 2 per 100,000 individuals. This condition accounts for 0.006% of hospital admissions, and is found in approximately 0.001% of exploratory laparotomies (Tessier).

Causation and Known Risk Factors

Women who use estrogen-containing oral contraceptives and smoke are at greater risk for mesenteric thrombosis.

Individuals who have undergone previous abdominal surgery and individuals who suffer from hyper-coagulable states are at increased risk for mesenteric thrombosis. Other predisposing factors include inflammation, such as pancreatitis; portal hypertension; enlargement of the spleen (splenomegaly); sickle cell disease; decompression sickness; paroxysmal nocturnal hemoglobinuria; malignancy; blunt abdominal trauma; and visceral infection. However, in half the cases, no underlying cause is found.

Diagnosis:

A high index of suspicion based upon history and clinical findings is necessary to make an early diagnosis.

History: Individuals with mesenteric thrombosis are usually asymptomatic until the onset of late complications. Once symptoms begin, abdominal pain is the most common complaint. The pain is usually vague and slowly progressive, with eventual localization over the affected segment of bowel. Individuals may also complain of nausea, vomiting, diarrhea, and anorexia.

Physical exam: Upon examination, a low grade fever may be noted. Examination of the heart may reveal tachycardia. Other physical findings may include abdominal tenderness, decreased bowel sounds, abdominal distension, and blood in the stool. Late in the course of the disease, paracentesis may demonstrate bloody peritoneal fluid.

Tests: Laboratory examinations do more to suggest rather than confirm the diagnosis of mesenteric thrombosis. Recommended studies include prothrombin time (PT), activated partial thromboplastin time (aPTT), complete blood count (CBC), and chemistries (which may show metabolic acidosis). In general, laboratory studies are unremarkable, though a leukocytosis with a left shift and elevated lactic dehydrogenase are usually present.

Definitive diagnosis of mesenteric venous thrombosis relies upon the demonstration of thrombus within the mesenteric veins on imaging studies. Although magnetic resonance (MR) venography is overall the most accurate imaging study for the diagnosis of mesenteric venous thrombosis, we suggest computed tomography (CT) of the abdomen as an initial screening study for acute or subacute mesenteric venous thrombosis. Abdominal CT more reliably demonstrates findings of focal or segmental bowel-wall ischemia, in addition to excluding other causes of acute abdominal pain, and is inexpensive and widely available. For patients in whom the diagnosis of acute mesenteric ischemia is uncertain, but a suspicion remains high, angiography (CTA, MRA, or catheter based) should be performed, though uncommonly necessary. The diagnosis will necessarily be made in the operating room in patients who present with signs of bowel infarction.

TREATMENT:

Patients with clinical signs of bowel infarction require surgical intervention with an open approach rather than laparoscopic exploration. The extent of bowel edema and resulting abdominal distention make a laparoscopic approach difficult, and insufflation of the abdomen can exacerbate mesenteric venous hypertension. There should be a low threshold for leaving the abdomen open to facilitate second-look operation. Whenever the viability of the intestine is in question, a second-look operation should be planned and performed as scheduled.

For patients with acute or subacute mesenteric venous thrombosis without indications for surgery, we initiate systemic anticoagulation to minimize extension of thrombus, rather than expectant management alone (includes bowel rest and decompression, fluid therapy and serial abdominal examination).

An adjunct to anticoagulation may include CATHETER DIRECTED THROMBOLYTIC (CDT) THERAPY or other ENDOVASCULAR TREATMENTS.

Prophylactic antibiotics are given to minimize bacterial translocation.

(Source: https://www.uptodate.com/contents/mesenteric-venous-thrombosis-in-adults)

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