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3-6-9 rule (bowel)

Last revised by Dr Mohamed Saber on 19 Oct 2020

The 3-6-9 rule is a simple aide-memoire describing the normal bowel caliber:

Above these dimensions, the bowel is generally considered dilated, and obstruction or an adynamic ileus should be considered.

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Cases and figures

  • Small bowel obstruction
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  • Large bowel obstruction
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  • Dilated appendix
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  • Cecal bascule
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