Mesenteric vein thrombosis

Background

The abdomen viewed from the front, showing the portal venous system, showing the superior mesenteric vein and its tributaries. (Lienal vein is an old term for splenic vein.)

• A rare (< 5% of all cases) subset of mesenteric ischemia that has a high rate of mortality approaching 50%.
• Risk factors include intrabdominal inflammation and hypercoaguability.

Intestinal Ischemic Disorder Types

• Ischemic colitis
  • Accounts for 80-85% of intestinal ischemia
  • Due to non-occlusive disease with decreased blood flow to the colon.
  • Causes decreased perfusion leading to sub-mucosal or mucosal ischemia only.
  • Typical to the "watershed areas" of the colon (Splenic flexure or Sigmoid)

• Acute mesenteric ischemia
  • Due to complete occlusion of mesenteric vessels
  • Complete transmural ischemia

• Mesenteric venous thrombosis
• Chronic mesenteric ischemia ("intestinal angina")

Clinical Features

Depends on subtype and disease can exist along a continuum.

• Acute-expect typical features such as severe abdominal pain that is out of proportion to exam findings. Rebound and guarding may occur. Time course usually over days.
• Subacute- abdominal pain can be vague and symptoms may be insidious over a period of days to weeks.
• Chronic- patients usually are asymptomatic and thrombosis is usually found on imaging incidentally. Some patients may have post prandial colicky abdominal pain that resolves.

Differential Diagnosis

Diffuse Abdominal pain

• Abdominal aortic aneurysm
  • Aortocaval fistula
• Acute gastroenteritis
• Aortoenteric fisulta
• Appendicitis (early)
• Bowel obstruction
  • Large bowel obstruction
    • Ogilvie's syndrome
  • Small bowel obstruction
  • Malignant bowel obstruction
• Bowel perforation
• Diabetic ketoacidosis
• Gastroparesis
• Hernia
• Hypercalcemia
• Inflammatory bowel disease
• Mesenteric ischemia
  • Mesenteric vein thrombosis
• Pancreatitis
• Peritonitis
• Sickle cell crisis
• Spontaneous bacterial peritonitis
• Volvulus

Evaluation

CT scan showing acute superior mesenteric vein thrombosis (black arrow) with bowel wall thickening (white arrowhead), mesenteric edema (black arrowhead) and ascites. Note the normal SMA enhancement (white arrow) and ratio of SMV to SMA diameters > 2.

Contrast enhanced CT (axial and coronal views) of the abdomen demonstrated a filling defect in the superior mesenteric vein (arrow), suggesting thrombus.

Workup

• Labs- CBC, CMP, Lipase, UA, HCG(when applicable), Lactate, Coags.
• imaging
  • from the ED stand point a multiphase contrast CT is the most accurate and timely.(Non-contrast, arterial phase, and venous phase).
  • oral contrast can help dilineate bowel thickness.
  • Magnetic resonance venography is another option if testing is non-diagnostic.

Diagnosis

• meseteric vein filing defect, bowel thickening, bowel hypoattenuation, bowel enhancement, pneumatosis, potential ascites.
• labs, other forms of imaging, and physical exam do not have high enough sensitivity to reliably exclude this diagnosis.

Management

Non-Operative

• • IVF
  • Bowel Rest
  • Bowel decompression
  • ABX
  • Anti-coagulation

Operative

• Reserved for patients with overt signs of intestinal necrosis or perforation