Obstructive Bowel Gas Pattern on X-ray

Obstructive bowel gas pattern means the small or large intestine is obstructed.  This can be a complete high grade obstruction where nothing gets through or a partial obstruction.  Patients often present with abdominal pain, distention and vomiting.

What does X-ray show in bowel obstruction?

X-rays of the abdomen are sometimes ordered to investigate a bowel obstruction.  Bowel obstruction will classically show dilated bowel loops, air-fluid levels within, with transition to normal appearing bowel at the site of blockage.

Not all bowel obstructions will show on X-ray.  This is because the bowel only shows up on X-ray when there is some air within.  A bowel obstruction can still occur when the bowel loops are filled with fluid.  This will be seen as an abdominal X-ray with little to no gas seen in the bowel.

Partial obstructions may show up with some of the classic findings of dilated bowel, air fluid levels and transition to normal bowel at the obstruction or may show few to none of these findings.   Some of the obstructions will fall into the non specific bowel gas pattern.

Causes of bowel obstruction


The cause of the obstructive bowel gas pattern on X-ray will rarely be apparent on X-ray.  The most common cause of an obstruction of the small intestine is fibrous adhesions or scar tissue.  These occur most commonly after you have had prior abdominal surgery or bouts of peritonitis.  We can not see this finding on X-ray and CT.  The absence of a visible cause of the blockage often indicates adhesions.


Additional causes of obstructive bowel gas pattern on X-ray can be abdominal hernias.  This occurs when bowel or other contents protrudes externally through the abdominal or pelvic wall.  This can also occur internally when contents of one abdominal compartment extends into another.


Cancer is another cause of bowel obstruction.  This can involve the small or large intestine.  The cancer will cause the blockage. We can not see the cancer on X-ray because it blends in with the surrounding tissues.   But further testing with CT and colonoscopy will provide the diagnosis.

Bowel inflammation

Inflamed bowel from various causes like inflammatory bowel disease, diverticulitis, ischemia (bowel starved of blood flow) are some of the causes.  This will cause the bowel to thicken and possibly become obstructed.

Other rarer causes of bowel obstruction can include intussusception when one segment of bowel telescopes into another.  Volvulus or twisting of the bowel.  Endometriosis can involve the bowel and cause a blockage.  Cancer can spread to the bowel and cause a blockage.

Since X-rays will not show all bowel obstructions, CT is often ordered when it is suspected.  CT will show all the bowel and most obstructions will be diagnosed.  Treatment consists of surgical consult and possible surgery, especially when there is bowel peroration or ischemia.

An obstructive bowel gas pattern on X-ray will often be further evaluated with CT as well.  This is to get more information about the cause and to see if there are any complications such as perforation or ischemia.




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