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SonoPhile

Small bowel obstruction is a common disease; its incidence in patients who present to the emergency department (ED) is estimated at 2–8%, and about 15% of these patients are admitted to the surgical unit

Ultrasound of Small Bowel Obstruction

  • Ultrasound Examination Setup:

    • Patient position: supine, spontaneously breathing

    • Equipment: Convex probe (2-6 MHz), high-frequency linear probe (7-12 MHz) for detailed loop assessment

  • Purpose:

    • Confirm/exclude other pathologies (differential diagnosis)

    • Avoid satisfaction errors in ileus diagnosis

  • Assessment Technique: Global View

    • Panoramic assessment from bottom to top with vertical probe movements starting from the right iliac fossa

    • Horizontal movements from right to left

  • Evaluation Criteria:

    • Identify dilated small bowel loops

    • Measure diameter, kinesis, parietal, and valvulae conniventes thickness

    • Assess presence/absence of free liquid between loops

    • Look for ancillary signs (e.g., bowel jumps)

  • Obstruction Identification:

    • Identify obstructive fulcrum and potential causes (hernia, extraluminal mass)

    • Locate obstruction point by recognizing specific morphological criteria of intestinal portions

  • Specific Morphological Criteria:

    • Stomach: Located by pronounced muscular layer, visible mucous folds in fluid distension

    • Small Intestine: Smaller diameter than colon, presence of valvulae conniventes (keyboard sign)

    • Colon:

      • Cecum and sigma as landmarks

      • Follow large intestine from these points

      • Left colon haustra not always clear

      • Right colon often shows only anterior wall due to gas

  • Importance of Cecum:

    • Evaluate degree of distension, last loop involvement, and ileus-cecal valve continence

This streamlined approach ensures comprehensive and systematic evaluation of the abdominal area to accurately diagnose and locate intestinal obstructions.

Ultrasound is a highly accurate imaging method for the diagnosis and staging of mechanical ileus of the small bowel, and the ultrasound findings fully reflect the evolutionary patterns of the disease. Moreover, ultrasound can be used to evaluate intestinal peristalsis in real-time, playing a key role in diagnosis and patient monitoring.

Conclusion

A dilated small bowel loop with a caliber of more than 3 cm (dotted line) with trapped feces defines a ‘small bowel feces sign’. Bowel walls appear thin, and the folds flatten.

‘Caliber jump’: a difference in caliber between the swollen loops upstream (white arrows) (a,b) and the collapsed loops downstream of the obstruction (black arrows) (a,b).

Credit to: Rosano, N., Gallo, L., Mercogliano, G., Quassone, P., Picascia, O., Catalano, M., Pesce, A., Fiorini, V., Pelella, I., Vespere, G., Romano, M., Tammaro, P., Marra, E., Oliva, G., Lugarà, M., Scuderi, M., Tamburrini, S., & Marano, I. (2021). Ultrasound of Small Bowel Obstruction: A Pictorial Review. Diagnostics (Basel, Switzerland), 11(4), 617. https://doi.org/10.3390/diagnostics11040617

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