Bowel wall air or pneumatosis intestinalis on X-ray is seen as lucent dark air pockets along the bowel wall. This is an important finding because it can indicate that there is ischemia of the bowel. This means that the bowel is starved of blood and can eventually lead to infarction and bowel wall death. This is a life threatening condition. Other causes of bowel wall air can be benign or a finding that needs no treatment. Often the distinction is made by the clinical doctors based on the condition of the patient.
Bowel wall ischemia leads to gas in the wall from bacterial overgrowth which releases gas. Gas will eventually leave the bowel wall and enter the circulation, which can also be seen on X-ray in the portal vein and its branches. The bowel can perforate which will release air into the abdomen. Eventually this can lead to sepsis or blood infection and death. The causes are varied but often are a result of arterial or venous blockage of the circulatory supply of the bowel.
Benign causes of air in the bowel wall or pneumatosis intestinalis are multiple. Intestinal inflammation like colitis can lead to air in the bowel wall. Air in the bowel wall can be seen after procedures like colonoscopy or NG tubes. Certain drugs like steroids and chemotherapy agents can cause this. Pulmonary disease like asthma or emphysema can also cause this finding.
Often, a CT scan will be ordered to investigate further. Causes of more worrisome air in the bowel wall will be air in the portal vein or it’s branches, bowel wall thickening, inflammatory changes, blocked blood vessels and air in the abdominal cavity. The patients clinical condition will also often indicate if something life threatening is occurring. A mimicker of this finding is air trapped between the bowel wall folds or intestinal contents. A CT will be more definitive.