Bowel obstruction / Ileus

Bowel obstruction / Ileus

What are the sites of bowel obstruction?

Small bowel
Large bowel

What is ileus?

Dilated bowel which may be from:

Paralytic
Obstructive

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 common causes of small bowel obstruction?

Post-op adhesions
Gallstone ileus
Intussusseption
Tumors

What are the common causes of large bowel obstruction?

Cancer colon
Fecal impaction
Diverticulitis

What are the anticipated imaging findings of bowel obstruction?

Dilated loops of bowel
Air fluid levels in the small bowel loops.

How do you distinguish small from large bowel?

Small bowel is in central abdomen
Large bowel is in the periphery of abdomen
Valvulae Connieventes crosses the entire width of small bowel
Haustra are seen partially across the width of large bowel
Bubbly appearance of feces indicates large bowel
Diverticula are present only in large bowel

Normal Bowel

Large bowel is identified by the sacculations called haustra scattered all along the colon.
The colon has fat filled tags called appendices epiploicae on its surface.
These haustra and epiploicae separate the large from the small intestine.
Colon is filled with feces which has bubbly appearance

The small bowel is located in the center of abdomen
Fairly narrow about 2.5 cm tube like structure winds compactly back and forth within the abdominal cavity
The small intestine is identified by valvulae circulares or circular folds on oral contrast study.

Plain film in a case with Small bowel obstruction

Multiple dilated small bowel loops are seen (white arrowheads).
There is fecal material in the right and left colon
(arrows).
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.

CT scan of another patient showing findings of small bowel obstruction:

A: Post op changes in abdominal wall. Arrowheads: Normal size of distal small bowel and Recto sigmoid (RS)
B: Arrowheads: Dilated small bowel loops. Arrow: Area of obstruction

Gall stone Ileus

Air in Bile duct
Dilated small bowel
Gall stone is not seen in this film and may overlie the sacrum where the dilated bowel seems to end. [Black arrow ]

Lower GI in a patient with Large bowel Obstruction

Dilated bowel loops proximal to the obstruction.
Arrow points to the etiology of obstruction.