Imaging Pearls ❯ Small Bowel ❯ SMA Syndrome
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- “In conjunction with an appropriate clinical history, several CT findings can suggest the diagnosis of SMA syndrome. These findings include narrowing of the aortomesenteric angle and distance, distension of the stomach and duodenum, and dilatation of the left renal vein with left-sided venous collaterals.”
Superior mesenteric artery syndrome: spectrum of CT findings with multiplanar reconstructions and 3-D imaging
Raman SP, Neyman EG, Horton KM, Eckhauser FE, Fishman EK
Abdom Imaging 2012 Feb 12 (Epub ahead of print)
- Epidemiology of SMA syndrome:
- 0.013–0.78% incidence based on upper gastrointestinal barium studies
- Females are more commonly affected
- Two thirds of patients are between 10 and 39 years old, although it has been reported even
in octogenarians (Figure 12).
- Most commonly associated with severe, debilitating illnesses such as malignancy,
malabsorption syndromes, AIDS, trauma and burns; and with scoliosis surgery - Indirect Radiologic Signs Helpful on Axial Images
- If multiplanar or 3D reconstructions typically performed only after an analysis of the axial
images, these indirect signs are helpful in deciding on further evaluation:
- Dilated left renal vein prior to passing between aorta and SMA
- Dilated venous collaterals, such as lumbar or gonadal vein
- Disease processes in the region - SMA Syndrome Pathophysiology and Direct Radiologic Findings
- Mean angle formed by the superior mesenteric artery and the aorta varies between 38 and
56° with range of 20 to 70° reported
- In SMA syndrome it diminishes to 6-16°
- Mean aortomesenteric distance is 10–28 mm . In SMA syndrome it diminishes to 2-8 mm - Superior Mesenteric Artery (SMA) Syndrome
- SMA syndrome is an uncommon but well recognized clinical entity characterized by
compression of the third, or transverse, portion of the duodenum (D3) between the aorta
and the superior mesenteric artery.
Other terms used for this condition:
– cast syndrome
– Wilkie syndrome
– arteriomesenteric duodenal obstruction
– aortomesenteric artery compression
– duodenal vascular compression
– chronic duodenal ileus