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GI -- Bowel obstruction

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When you come upon a case of bowel obstruction, what are the things YOU must assess for?
Level of obstruction



Cause of obstruction



Presence of enhancement of all small bowel loops (can always see enhancement in normal small bowel), and in large bowel if possible.
What are the three most common causes of small bowel obstruction in adult?
1) Adhesions (65%)



2) External hernia (15%)



3) Neoplasm (15%)
What are they in the colon?
1) Colon CA (65%)



2) Diverticulitis (20%)



3) Volvulus (10%)
What is the point then?
Colonic obstruction and SBO have totally different etiologies, with SBO being benign causes usually, and colonic obstr malignant usually.
What is a common cause of bowel obstruction in younger patients (i.e. 20s)?
Inflammatory pseudotumor (inflammatory myofibroblastic tumor)
What do you do when encountered with SBO in a "virgin" abdomen?
Pretty much rules out adhesions. Must search hard for a cause, because there is always a good reason.


Hernia, mass, midgut volvulus with congenital Ladd bands, patient with cystic fibrosis with inspissated feces.
What additional abdominal finding do CF patients get?
FATTY replacement of pancreas
What is the cause of small bowel feces sign?
Stasis of material in the small bowel
What are the bowel obstruction situations most likely to result in strangulation?
1) Closed loop obstructons



2) Volvulus



3) High grade obstructions (due to increased perfusion pressure) -- high grade obs happens with CA
What is sufficient to make dx of closed loop obstruction?
1) Small bowel obstruction


2) U-shaped loop of distended bowel



3) Clouding of the adjacent mesentery


OR


See distended loop of bowel with two limbs in close contiguity and obstruction proximal to this region.
What is a sign of bowel ischemia that predates absence of enhancement?
Target sign: See mural stratification or just see thickening and prominent enhancement of the mucosal surface.
When the ischemia progresses to infarction, what occurs?
The wall goes from thickened and enhancing to non-enhancing and almost paper thin. Next comes pneumatosis.
Post-op patient with dilated ascending colon and SBO with collapsed descending colon. You want to r/o an obstructing lesion. CT is indeterminate. What do you do?
Put patient on fluoro table, do single contrast BE just to demonstrate normal transverse colon. If normal, you know patient just has a variant pattern of adynamic ileus.
When is enteroclysis preferred over CT?
Chronic recurrent obstruction. Enteroclysis is good for challenging the small bowel to look for areas of poor dilation, which may reflect adhesions that can be removed laparoscopically.

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