Acute abdominal series

Technique

3 Films:

1. Upright chest film
   • Rule-out free air
2. Upright abdominal film
   • Look for air-fluid levels
3. Supine abdominal film (KUB = just supine film)
   • Width of bowel loops most visible (estimate of amount of distention)

If pt does not tolerate upright position, left lateral decubitus abdominal film can substitute

Images

Normal

Small bowel obstruction

Upright chest radiograph demonstrating free intra-abdominal air below the diaphragm. (Black arrows demonstrate the air below the diaphragm)

Cecal volvulus. Featureless dilated gas filled viscus, representing the volved caecum, in the left upper quadrant (black arrows) and small bowel obstruction (white arrows). No colonic gas is identified.

Multiple foreign bodies in the bowel; body-packing with multiple "balls" of hashish.

Button battery foreign body in the stomach.

Interpretation

Differentiating large and small bowel

• Small bowel has lines (plica circulares) all the way through the bowel
• Large bowel has lines (haustra) only halfway through the bowel

Bowel Diameters: 3/6/9 rule

• Small bowel - 3 cm
• Colon - 6 cm
• Cecum - 9 cm

Small bowel obstruction

• Air in colon or rectum makes complete obstruction less likely (esp if symptoms >24hr)

Abdominal x-ray has poor Sn and Sp for SBO

• If concerned need CT

Indications

• Ruling out free air under the diaphragm (e.g. perforated ulcer)
• Ruling out radio-opaque abdominal foreign body
• Ruling in SBO (i.e. to avoid need for CT scan)

Do NOT use as the sole study to rule out SBO (poor sensitivity)

Do NOT use to rule out generalized peritonitis (almost no sensitivity for diagnoses such as appendicitis)

Do NOT use to diagnose constipation (many patient with acute abdomen will have "copious stool")

See Also

• SBO