Small bowel obstruction

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Small bowel obstruction, abbreviated SBO, is a common pathology managed by general surgeons.

This article gives an overview of SBOs. Its primary focus is benign causes of SBO that have nonspecific pathologic findings.

Specific causes definitively identified by pathology, e.g. adenocarcinoma, or by clinical history/pathology, e.g. Crohn's disease, are dealt with separately.

General

  • Radiologic/clinical diagnosis.
  • The conventional thinking is the sun should never set on a SBO in a virgin abdomen, i.e. a laparotomy is required to exclude serious pathology in an unoperated abdomen.
    • Approximately 10% of virgin (or previously unoperated) abdomens (in a series from 2014) had an unknown malignancy as the underlying cause.[1]

The usual causes of bowel obstruction (large & small) are (mnemonic) SHAVING:

  • Strictures (think IBD).
  • Hernias.
  • Adhesions.
  • Volvulus.
  • Intussusception.
  • Neoplasia.
  • Gallstone ileus.

The top three are:[2][3]

  • Adhesions > hernias > neoplasms.

In the context of bowel obstructions and IBD, pathologists often see resected stomas (that were put in place emergently). These specimens are usually fairly straight forward.

Radiology

  • Air-fluid levels.

Gross

  • +/-Adhesions.
  • +/-Bowel contorted.
  • +/-Luminal narrowing +/-proximal dilation.
  • +/-Serosal exudate.
    • Suggestive of perforation.

Microscopic

Features:

  • +/-Adhesions (serosal).
    • Dense fibrous tissue replaces the adipose tissue.
    • +/-Increased vascularity.
  • +/-Submucosal fibrosis.
  • +/-Serositis - seen in small bowel perforation.
  • +/-Foreign body-type granuloma - due to previous surgical intervention.

DDx:

Sign out

Small Bowel, Resection:
     - Small bowel wall with focal ischemia and fibrous adhesions, surgical
       margins appear viable.
     - NEGATIVE for significiant vascular disease in vessels examined.
     - NEGATIVE for malignancy.

Block letters

SMALL BOWEL, RESECTION:
- SMALL BOWEL WITH FIBROUS ADHESIONS (EXTENSIVE) ASSOCIATED WITH FOCAL LUMINAL
  NARROWING.
- NEGATIVE FOR DYSPLASIA AND NEGATIVE FOR MALIGNANCY.
SMALL BOWEL, RESECTION:
- SMALL BOWEL WITH FIBROUS ADHESIONS (EXTENSIVE), FOCAL LUMINAL NARROWING AND A
  FOREIGN BODY-TYPE GRANULOMA.
- NEGATIVE FOR DYSPLASIA AND NEGATIVE FOR MALIGNANCY.

Ischemic changes

SMALL BOWEL, RESECTION:
- SMALL BOWEL WITH ISCHEMIC CHANGES, FIBROUS ADHESIONS, FOCAL SEROSITIS AND MURAL
  MICROABSCESS FORMATION.
- NO SIGNIFICANT VASCULAR PATHOLOGY APPARENT.
- NEGATIVE FOR MALIGNANCY.

See also

References

  1. Beardsley, C.; Furtado, R.; Mosse, C.; Gananadha, S.; Fergusson, J.; Jeans, P.; Beenen, E. (Aug 2014). "Small bowel obstruction in the virgin abdomen: the need for a mandatory laparotomy explored.". Am J Surg 208 (2): 243-8. doi:10.1016/j.amjsurg.2013.09.034. PMID 24565365.
  2. URL: http://www.emedicine.com/EMERG/topic66.htm. Accessed on: 19 April 2011.
  3. Greenwald, J.; Heng, M. (2007). Toronto Notes for Medical Students 2007 (2007 ed.). The Toronto Notes Inc. for Medical Students Inc.. pp. GS21. ISBN 978-0968592878.