What is Bowel Gas on X-ray?

Bowel gas is seen on many X-rays of the abdomen and is often a normal expected finding. Gas is either swallowed or formed by the breakdown of foods in your colon. Bowel gas looks dark on an X-ray in a bowel loop. A few or many bowel loops will have gas on an X-ray and can be entirely normal.

Mostly only those loops which contain gas are seen on an X-ray. The bowel loops which do not contain gas blend with the other soft tissues and fat of the abdomen which are white. Therefore, bowel gas is very helpful to diagnose conditions such as inflamed bowel or obstruction since it makes the bowel visible. Sometimes the bowel in these conditions will not contain gas. In these cases, an X-ray will often not be able to see these conditions.

Bowel gas therefore greatly aids in the diagnosis of abnormalities on X-rays. Gas allows the bowel loops to be visible on X-ray. This allows us to see how big the loops of bowel are. In the case of bowel obstruction, we will see dilated bowel loops filled with gas and fluid. Often a CT is done to confirm the diagnosis since other conditions can also result in dilated small bowel loops.

Bowel gas also allows us to see the wall of the bowel in some cases. Inflamed bowel will have thickened wall. This can sometimes be seen on X-ray but a CT is much better for this condition. Gas in the bowel can also allow us to see twisted colon or volvulus.

Bowel gas which escapes the bowel into the abdominal cavity is called free air. This means that there has been a perforation of the bowel or there is a disruption or tear of the wall. This is a surgical emergency. The abdominal cavity is sterile while the bowel has food and bacteria. This will cause peritonitis or an inflammation of the abdominal cavity if the contents of bowel spill. This can be a deadly condition and needs to be diagnosed rapidly.

Simply having bowel gas can also cause pain or discomfort and mimic more dangerous conditions like appendicitis or heart attack. Therefore, many times, simply having bowel gas alone is normal. Its more concerning when we see see associated findings like dilated or thickened bowel loops.

Having no bowel gas at all can also be abnormal in the right setting. Sometimes bowel which is obstructed or blocked will be filled with fluid and not seen on an X-ray at all. This can also be a normal finding. Your clinical doctor will determine based on his findings whether you need a CT.

Bowel gas alone is a normal finding in many cases. Depending on the appearance of the bowel, it can also represent a more dangerous condition like bowel obstruction or inflammation. It is important for your clinical doctor to consider How your doing and what any other tests are showing. This will determine the need for further testing with CT, any specialty consults and whether you need to be admitted to the hospital.