Small bowel obstruction vs Large bowel obstruction
How to tell Small bowel obstruction and Large bowel obstruction apart when a board question makes them look alike.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
Predominant colonic dilation with distal obstructing lesion indicates large bowel obstruction.
Side by side
Early vomiting with crampy pain and multiple dilated central small-bowel loops suggests small bowel obstruction.
Marked abdominal distension with delayed feculent vomiting and peripheral colonic dilation suggests large bowel obstruction.
Adhesions or hernia most often block small-intestinal transit causing proximal fluid and gas accumulation.
Colonic tumor or volvulus blocks distal large bowel causing progressive closed-loop distension.
CT shows transition point with small-bowel diameter above 3 cm and collapsed distal bowel; common causes include postoperative adhesions and incarcerated hernia.
CT shows colonic dilation above 6 cm, cecum often above 9 cm in severe cases, and obstructing lesion such as left-sided cancer or sigmoid volvulus.
The trap
All bowel obstruction is managed identically with prolonged conservative care. Large bowel obstruction from malignancy or closed-loop volvulus often needs urgent decompression or surgery to prevent perforation.
The repair move
Next best step: begin IV fluids, electrolyte correction, and bowel rest for any obstruction, then branch by level and cause. Suspected adhesive small bowel obstruction without peritonitis can receive trial nonoperative management with NG decompression. Large bowel obstruction from tumor or volvulus needs urgent surgical or endoscopic decompression planning.
Try a free question
CoreA 52-year-old man with prior appendectomy has crampy abdominal pain, vomiting, and CT showing multiple dilated small-bowel loops with a single transition point and no peritoneal signs. What is the next best step in management?
Show answer and explanation
Answer: A. Trial nonoperative management with NG decompression and IV fluids. Uncomplicated adhesive SBO without strangulation signs can be managed initially with nonoperative decompression and resuscitation.
Why the other choices are tempting
- B. Wrong. Colectomy targets colonic pathology, not straightforward adhesive SBO.
- C. Wrong. Untreated SBO risks ischemia and dehydration.
- D. Wrong. Bowel prep is unsafe in mechanical obstruction.
- E. Wrong. Antimotility drugs can worsen obstruction.
Flashcards
Tap a card to flip it.
Which imaging distribution favors large bowel rather than small bowel obstruction?
Peripheral colonic dilation with distal colonic transition point.
What common etiology should be assumed first in postoperative small bowel obstruction?
Adhesive disease.
Quick answers
What is the fastest way to tell Small bowel obstruction from Large bowel obstruction?
Predominant colonic dilation with distal obstructing lesion indicates large bowel obstruction.
What is the key clue for Small bowel obstruction?
Early vomiting with crampy pain and multiple dilated central small-bowel loops suggests small bowel obstruction.
What is the key clue for Large bowel obstruction?
Marked abdominal distension with delayed feculent vomiting and peripheral colonic dilation suggests large bowel obstruction.
What is the common trap with Small bowel obstruction vs Large bowel obstruction?
All bowel obstruction is managed identically with prolonged conservative care. Large bowel obstruction from malignancy or closed-loop volvulus often needs urgent decompression or surgery to prevent perforation.