Is a Nonspecific Bowel Gas Pattern Normal?

The gastrointestinal system frequently contains gas.

A nonspecific bowel gas pattern may be caused by factors, such as:

• Microorganisms in the colon that produce gas
• Carbonated beverages
• Swallowed air
• Complications after surgery
• Abscess
• A growth/tumor (often due to scirrhous carcinoma or lymphoma)
• Obstruction
• Gastritis
• Hiatal hernia (either stomach or duodenal)
• Neurological bowel dysfunction
• Harmful megacolon
• Volvulus
• Lack of or diminished peristalsis (wave-like muscular contractions that transport food through the digestive tract)

A plain abdominal radiograph or X-ray is one of the most frequently needed tests in emergency care. The term “nonspecific abdominal gas pattern” is frequently used by emergency physicians in their initial interpretations.

• A recent survey of radiologists at community-based teaching hospitals revealed that 70 percent of the radiologists used this term
• 65 percent of these radiologists believed the phrase to mean “normal or probably normal”
• 22 percent said they couldn’t tell if the findings were normal or abnormal
• 13 percent said they used the term to indicate that the findings were “abnormal but it was unclear whether they were caused by mechanical obstruction or a dynamic ileus (due to spasm of a bowel segment)”

In the same study, 44 percent of the responding physicians who got the report classified it as “normal,” 51 percent classified it as “normal or abnormal” and 5 percent classified it as abnormal, denoting either mechanical obstruction or adynamic ileus. The phrase can mean several different things to radiologists and referring doctors. At one extreme, it seems to denote a normal situation, whereas, at the other extreme, it is seen as a pathologic state, such as obstruction.

The use of the phrase “nonspecific abdominal gas pattern” has been discouraged in previous communications, but it is still in use today. Reasons for this should be considered.

According to a study, there are some patients whose abdominal radiographs do not exhibit "normal," "possible small intestinal obstruction," or "definite small bowel obstruction" gas patterns. It may be tough to "ignore" or give up this interpretation because there isn't a recommendation that can be used in its place.

Different intestinal gas patterns include:

• A "normal" intestinal gas pattern is characterized as either the lack of small intestinal gas (without an aberrant rise in abdominal density or loss of soft tissue planes) or the presence of gas within a few (three to four) variously shaped small intestine loops with a diameter of less than 2.5 cm. Additionally, a non-distended colon has a typical distribution of gas and/or feces.
• "Mild small bowel stasis" is defined as cases exhibiting single or multiple loops of the borderline or a slightly dilated small intestine (2.5 to 3 cm) with three or more air-fluid levels on upright or decubitus films. The small intestine does not have an excessive amount of colonic distention. A colon that is not distended contains gas and/or feces. Although it does not distinguish between a mechanical obstruction and a minor reflex or dynamic ileus, the phrase is used to denote an irregular gas distribution. The individuals in this group may have the reflex or reactive ileus related to a variety of events, such as trauma, severe illness, or urinary tract calculus, or they may have a low-grade obstruction that is difficult to diagnose clinically. Some might be connected to air swallowing and medication-induced hypoperistalsis.
• The definition of a “possible” small bowel obstruction (SBO) pattern is unequivocally the presence of dilated numerous gaseous and/or fluid-filled loops of the small intestine with a mild quantity of colonic gas, but the degree of distention of the small intestine relative to the colon is insufficient to render a conclusive diagnosis. Although air-fluid levels are usually apparent, diagnosing SBO involves some uncertainty.
• A "definite" SBO pattern refers to an abnormal and disproportionate gaseous and/or fluid distention of the small bowel compared to the colon (or other segments of the small intestine). The diagnosis of SBO is seen as being unambiguous because air-fluid levels are obvious.