Surgery (small bowel obstruction)

Where the cause of small bowel obstruction is indeterminate, a paramedian incision is used to gain access to the abdominal cavity. Caution must be exercised when incising the peritoneum - a distended loop of bowel may lie below.

The first step is to decide whether small or large bowel obstruction is present. The caecum is sought; this frequently requires the displacement of overlying coils of small intestine. An enlarged caecum is indicative of large bowel obstruction whereas a flaccid caecum usually confirms the presence of small bowel obstruction.

When small bowel obstruction has been confirmed, discovering the site of the lesion is the next objective. As much of the small intestine as possible is delivered from the wound and a thorough examination is undertaken. The locale is characterised by the abrupt transition between distended and collapsed loops of bowel. In some cases of extrinsic obstruction, e.g. due to adhesions, one site of pathology may not be obvious and decompression may be advantageous.

Decompression may be through one of several routes:

• manual manipulation of gas and fluid back to the stomach where it is removed via nasogastric aspiration
• insertion of a large-bore tube proximal to the point of obstruction, suction, and then careful closure of the wound - becoming less popular because of the risk of contamination
• insertion of a fine needle obliquely through the taenia coli to drain gas

Definitive management of the cause of obstruction is then indicated, e.g.:

• resection and anastomosis for tumours and strictures
• dividing adhesive bands
• manually coaxing an obstructive bolus to the caecum