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Large Bowel Obstruction

The most common cause of this is a Tumour. Other causes include:

  • Strictures - Secondary to Diverticular disease, IBD, Surgical anastomosis

  • Volvulus - Sigmoid (more common in older patients), Caecal (more common in younger patients)

  • Hernias

  • Adhesions

Patients typically present with:

  • Crampy abdominal pain

  • Abdominal distension

  • Absolute constipation (no faeces or flatus)

  • Bilious vomiting – More common in SBO, but occurs in late LBO


Closed-Loop Obstruction:

This occurs when there are 2 points of obstruction along the bowel. It can be caused by:

  • Adhesions in 2 areas

  • Hernias

  • Volvulus

  • 1 point of obstruction in large bowel with a competent ileocaecal valve


This is a surgical emergency as the closed loop will continue to expand, leading to ischaemia and perforation.


Investigations:

  • A-E assessment

  • Bloods - FBC, U&Es, Lactate, VBG

    • U&Es to check for any electrolyte imbalances

    • Lactate will be raised in bowel ischaemia

    • VBG will show metabolic alkalosis due to vomiting (loss of acid)

  • AXR - Shows dilated bowel loops and Haustral markings

  • Erect CXR - To check for pneumoperitoneum if suspected perforation

  • CT Abdo – May establish cause e.g. tumour

“Flat abdominal film of a patient with a large bowel obstruction” © James Heilman (Licensed under CC BY-SA 3.0) https://creativecommons.org/licenses/by/3.0/


Management:

Conservatively with NBM, Drip and Suck (IVF and NG aspiration for decompression), Antiemetics

  • Metoclopramide should be avoided as it's a prokinetic, therefore may worsen the obstruction and increase the risk of perforation.


Decompression of sigmoid with flexible sigmoidoscope can be done to treat a volvulus.


Surgical option is a bowel resection, which can involve primary anastomosis or stoma formation.

  • Malignant LBO patients, who aren’t candidates for surgery, can have palliative stenting to relieve symptoms



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