Interesting Case - Small Bowel

Symptoms

Abdominal pain

Diagnosis

Long segment closed loop obstruction of the small bowel

Investigation

Left Image: Axial CT demonstrating some features of a closed loop bowel obstruction. The yellow arrow demonstrates beaking of bowel at the point of obstruction. The orange arrow shows extensive oedema in the small bowel mesenteric folds. The image also shows the dilated obstructed loop of small bowellying on the left side of the abdomen (to the right side of the image) and mesenteric vessels radiating to the point of obstruction (unlabelled).

Centre Image: Coronal CT showing oedema in the small bowel mesentery with vessels radiating towards the point of obstruction.

Right Image: Coronal CT in a different patient with closed loop small bowel obstruction and haemorrhagic infarction of the small bowel. The red arrow points towards a region of bowel wall thickening. Note the mesenteric oedema.

Discussion

Closed loop small bowel obstruction is a specific type of bowel obstruction that occurs when a segment of bowel is obstructed at two points by a single constrictive lesion. It involves the bowel and its mesentery. The obstruction may involve a short or long segment of small bowel.

This is usually due to an internal hernia, twisting of the small bowel and its mesentery (volvulus) or adhesions.

Because closed loops small bowel obstructions involve a single lesion and the small bowel mesentery is involved in the process, they are particularly prone to strangulation, defined as obstruction associated with vascular compromise.

CT is the radiological investigation of choice in assessing the presence of small bowel obstruction and its cause.

The most important finding in a closed loop small bowel obstruction is demonstrating a loop of dilated bowel, the ends of which narrow in close proximity, a collapsed efferent limb, and an afferent limb. The latter is frequently not significantly dilated. Other imaging findings include a twisting or twirling of the mesenteric vessels, mesenteric vessels radiating out from a single point, and a beak or point of the small bowel where it is twisted.

CT is also useful for detecting strangulation or vascular compromise. Important findings include bowel wall thickening, absent enhancement (although enhancement is highly variable), oedema in the mesentery and pneumatosis (gas in the bowel wall).