What is a mesenteric artery ultrasound?
Ultrasound of the mesenteric artery/arteries is used to demonstrate disease that impacts the health and survival of the intestines and portions of the stomach. The arterial supply to the intestines consists of:
- The superior mesenteric artery (SMA)
- The inferior mesenteric artery (IMA)
Both of these are branches off the descending abdominal aorta. Because the collateral circulation to the organs supplied is not briskly confluent and therefore only functions for transient periods of inadequate perfusion, prolonged hypoperfusion due to mesenteric artery disease can risk devastating ischemia and tissue death over time. The arterial supply at the splenic flexure and the rectosigmoid junction are particularly susceptible areas.
The Superior Mesenteric Artery
The superior mesenteric artery, via its branches, supplies blood perfusion to the pancreas, a portion of the stomach, the small intestines (duodenum, jejunum, and ileum), and portions of the large bowel.
The Inferior Mesenteric Artery
The inferior mesenteric artery, via its branches, supplies blood to the transverse, descending, and sigmoid colon and the rectum.
Mesenteric Artery Ultrasound
Ultrasound of the mesenteric arteries is used to identify stenosis, plaque, or embolic occlusions that can interrupt the blood supply to the entire intestinal system, spleen, and portions of the liver and stomach. Duplex ultrasound, a combination of:
- B (brightness) mode: Renders an image based on the differences of tissue density reflected back and of
- Doppler ultrasound technology: Which reflects high frequency sound waves off of red blood cells to discern motion and blood flow is useful to identify arterial stenosis or occlusion in the superior mesenteric artery from atherosclerosis or arterial thromboembolic disease.
- CT and MRI imaging: Used to confirm the diagnosis of acute mesenteric ischemia. Contrast is generally not used in these advanced imaging protocols, due to its tendency to obscure mesenteric vessels and bowel wall integrity, which can delay the diagnosis. Such a diagnosis is a true life-threatening emergency for which any delay can create unnecessary mortality. Of CT and MRI, CT is preferred due to its ready availability in most settings and its speed of rendering results where speed is a priority.
- Direct imaging: Is done via endoscopic colonoscopy or rectosigmoidoscopy to confirm a diagnosis of ischemic colitis.