X-rays of the abdomen are important in diagnosing the presence of small bowel obstruction. When obstruction occurs, both fluid and gas collect in the intestine. They produce a characteristic pattern called "air-fluid levels". The air rises above the fluid and there is a flat surface at the "air-fluid" interface.
Update Date 7/25/2012
Updated by: Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, Washington; and Joshua Kunin, MD, Consulting Colorectal Surgeon, Zichron Yaakov, Israel. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.