Bowel obstruction / Ileus
What are the sites of bowel obstruction?
What is ileus?
Dilated bowel which may be from:
What are the common causes of ileus?
- Paralytic ileus occurs when there is inflammation in the peritoneum, most often following abdominal surgery, or other inflammations, like appendicitis, pancreatitis, etc.
- Normal postoperative ileus lasts 48 hours.
- The absence of bowel sounds, flatus, or bowel movements beyond the expected period indicates delayed resolution, or obstructed ileus.
What are the radiological findings of ileus?
- Distended bowel with multiple air-fluid levels
- Gas seen in the rectum
How is it different from bowel obstruction?
- There will be paucity of gas in bowel beyond the site of obstruction, unlike in paralytic ileus where gas can be seen in the rectum.
- Distended bowel loops proximal to site of obstruction. This will depend on whether it is small bowel or large bowel obstruction.
- Air fluid levels noted in bowel.
What are the useful imaging procedures in the evaluation of bowel obstruction ?
- Plain film serves as a screening procedure to detect bowel obstruction.
- Supine and erect films are often done to look for dilated loops of bowel and air fluid levels.
- However, comparing various studies of the efficacy of plain abdominal films in working up SBO show a wide range of sensitivity and specificity.
- Sensitivities ranged from 41 to 86% and specificities range from 25 to 88%.
- CT abdomen provides detailed information including the possible etiology for obstruction.
- CT with PO and IV contrast has a sensitivity and specificity of 100 and 83%. If the bowel is ischemic, then specificity decreases to 61%.
- Lower GI is rarely done nowadays.
What are the radiological findings of small bowel obstruction?
The characteristics of small bowel obstruction include:
- Multiple air-fluid levels in dilated centrally located loops of intestine with
- Visible valvulae conniventes
- Absence or paucity of colon gas
Absence or paucity of colon gas
What are the common causes of small bowel obstruction?
- Post-op adhesions
- Gallstone ileus
What are the radiological findings of large bowel obstruction?
- Obstructed colon usually appears as a peripherally located distended bowel with haustral markings.
- No air distal to site of obstruction.
- Sometimes the mass may be seen.
What are the common causes of large bowel obstruction?
- Cancer colon
- Fecal impaction
Small bowel obstruction
- Multiple dilated small bowel loops are seen (white arrowheads).
- There is fecal material in the right and left colon
- Air is seen in the rectum.
- The surgical staples indicate recent abdominal surgery (black arrowheads).
Small bowel obstruction
Cross lateral view shows multiple dilated fluid filled loops of bowel with air fluid levels.
- A: The arrow points to post op changes in the abdominal wall. Arrowheads point to the normal size of distal small bowel and recto-sigmoid (RS).
- B: Arrowheads point to dilated small bowel loops. The arrows point to the area of obstruction.
Large bowel Obstruction
- Dilated bowel loops proximal to the obstruction
- Arrow points to the etiology of obstruction.