Mesenteric Ischemia

  • Celiac truck supplies blood to the stomach and duodenum
  • SMA supplies blood to the rest of the small bowel and proximal colon
  • IMA supplies blood to the distal colon and rectum

Arterial flow can be blocked because of emboli (atrial fibrillation)

Venous flow can be blocked because of thrombosis (hypercoagulable states)

Effective flow can be severely decreased in shock states (sepsis, hemorrhage)

  • Atrial fibrillation
  • Pain with PO intake (intestinal angina)
  • SEVERE pain

The most classic finding is “Pain out of proportion to exam”

  • Lactic acid reportedly 100% sensitive according to some texts
  • CT scan WITH contrast (or even better, a CTA) for additional confirmation if your pretest suspicion is high

Analgesics and antibiotics. Surgery consult if intestines necrotic on imaging. Potentially vascular surgery consult as well if intestines salvageable.

Small Bowel Obstruction

  • QUESTION: What is the most common cause of mechanical small bowel obstruction?
    • ANSWER: Adhesions

Not all small bowel obstructions are mechanical, don’t forget that ileus can cause a similar pattern as well (electrolyte abnormalities, recent surgery, opiates, multi-system trauma)


Severe crampy pain with vomiting, bloating, and decreased bowel movements/flatus. History of multiple abdominal surgeries (high risk for adhesions)


Abdominal distention and tenderness. If peritoneal signs develop, this is a very bad condition and patient may be developing ischemic/necrotic bowel.

  • Most common test is CT scan with IV contrast
  • Abdominal x-ray sometimes gets ordered but has fallen out of favor for multiple reasons (decreased sensitivity, difficulty localizing obstruction, unable to rule out alternative diagnoses
  • Using oral contrast with the CT scan is also falling out of favor primarily due to the time constraints demanded of modern medicine.

Fluids, Analgesics, Antiemetics +/- Antibiotics if ischemia is developing. Obtain a surgery consult.

  • QUESTION: Should you order an NG tube?
    • ANSWER: NG tubes have been reported to be one of the most painful procedures one can endure. On the other hand, you can find online videos of people putting these in without any discomfort. It will end up being a risk/benefit discussion with your attending. The benefit is that decompressing the stomach will frequently improve the patient’s symptoms to a significant extent.
Additional Reading
  • American College of Radiology mesenteric ischemia imaging (ACR)
  • American College of Radiology small bowel obstruction imaging (ACR)