Closed loop obstruction
Closed loop obstruction is a specific type of small bowel obstruction in which two points along the course of a bowel are obstructed at a single location thus forming a closed loop. Closed loop usually rotates around its axis, forming a small intestinal volvulus.
This is usually secondary to adhesions, a twist of the mesentry or herniation. A similar related pathology is the large bowel volvulus (either sigmoid or caecal). In closed loop obstruction, there is a high risk of strangulation and bowel infarction (10-35%).
Some or all of the following signs may be demonstrated on CT:
- marked distension of a segment of small bowel
- radially distributed, C or U-shaped small bowel loops
- "beak sign": of the tapering bowel loops at the point of obstruction
- "whirl sign": of the tightly twisted mesentery
- two adjacent collapsed loops of bowel
- if strangulation is present, signs of bowel ischaemia
- 1. Delabrousse E, Lubrano J, Jehl J et-al. Small-bowel obstruction from adhesive bands and matted adhesions: CT differentiation. AJR Am J Roentgenol. 2009;192 (3): 693-7. doi:10.2214/AJR.08.1550 - Pubmed citation
- 2. Balthazar EJ, Birnbaum BA, Megibow AJ et-al. Closed-loop and strangulating intestinal obstruction: CT signs. Radiology. 1992;185 (3): 769-75. Radiology (abstract) - Pubmed citation
- 3. Brant WE, Helms CA. Fundamentals of diagnostic radiology. Lippincott Williams & Wilkins. (2007) ISBN:0781761352. Read it at Google Books - Find it at Amazon
- 4. Federle MP, Jeffrey RB, Woodward PJ et-al. Diagnostic Imaging: Abdomen, Published by Amirsys®. Lippincott Williams & Wilkins. (2009) ISBN:1931884714. Read it at Google Books - Find it at Amazon
- 5. Duda JB, Bhatt S, Dogra VS. Utility of CT whirl sign in guiding management of small-bowel obstruction. AJR Am J Roentgenol. 2008;191 (3): 743-7. doi:10.2214/AJR.07.3386 - Pubmed citation