7. Small Bowel Obstruction Ultrasound

Small Bowel Obstruction Ultrasound

Small Bowel Obstruction (SBO) is a common type of mechanical GI obstruction, representing 80% of cases (versus 20% large bowel obstruction). Ultrasound can be used to detect SBO (Taylor).

Classic signs and symptoms for SBO include cramping abdominal pain, and abdominal distension with nausea.

The ultrasound technique for detecting SBO is known as “mowing the lawn” or the “lawnmower technique”. Starting in the RLQ and using graded compression, slowly scan the abdominal quadrants as depicted below.

lawnmower technique for Ultrasound for SBO

Ultrasound findings for small bowel obstruction include:

  • Dilated bowel loops (diameter > 3cm)
  • Ineffective or absent peristalsis, which will be seen as a “whirling” of intra-luminal contents
  • Collapsed colonic lumen

When 2 of 3 of these findings are present, POCUS has sensitivities and specificities of over 90% to detect SBO (Unlüer et al).

Abdominal Ultrasound Small Bowel Obstruction Dilated Loops Haustra
Dilated bowel loops in the small bowel with haustra.