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.)

• Local thrombus formation in mesenteric veins, which impairs venous return of the bowel
  • A rare (< 5% of all cases) subset of mesenteric ischemia that has a high rate of mortality approaching 50%.
  • Can be associated with concurrent portal vein thrombosis
• Risk factors include intraabdominal inflammation (pancreatitis, IBD) and hypercoagulability (protein C/S deficiency, malignancy).
• A previous history of DVT is reported in approximately 20-40 percent of patients with mesenteric venous thrombosis

Intestinal Ischemic Disorder Types

• Ischemic colitis
• Acute mesenteric 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.
• Exam may show distended abdomen or positive fecal occult blood
• Rebound and guarding may occur if bowel wall edema progresses to ischemia

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 standpoint a multiphase contrast CT is the most accurate and timely (Non-contrast, arterial phase, and venous phase).
  • Oral contrast can help delineate bowel thickness.
  • Magnetic resonance venography is another option if testing is non-diagnostic.
  • Doppler ultrasonography can detect thrombosis in larger veins but is less sensitive

Diagnosis

• Mesenteric vein filling defect is diagnostic
  • Bowel thickening, bowel hypoattenuation, bowel enhancement, fat-stranding pneumatosis, potential ascites may also be seen
• Labs, other forms of imaging, and physical exam do not have high enough sensitivity to reliably exclude this diagnosis.

Management

Non-Operative

• Anticoagulation is the mainstay of treatment
  • Depending on disposition, can utilize unfractionated heparin, LMWH, or DOACs
  • Consider if there are no planned operative management
• IVF, electrolyte repletion, and pain control
• Bowel Rest
• Bowel decompression
• Antibiotics

Operative

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

Disposition

• Consider admission depending on clinical status

See Also

• Portal vein thrombosis