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

Interpretation

Differentiating large and small bowel

Location	Size	Lines
Small bowel	3 cm	All the way through the bowel (plica circulares)
Colon	6 cm	Only halfway through the bowel (haustra)
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

Images

• 

  Normal

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  Small bowel obstruction

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  Large bowel obstruction (Cecal volvulus; black arrows), with small bowel obstruction (white arrows).

• 

  Free intra-abdominal air below the diaphragm.

• 

  Body-packing with multiple foreign bodies ("balls" of hashish).

• 

  Button battery in stomach.

Indications

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

Do NOT use as the sole study to rule out bowel obstruction (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