Intestinal Pneumatosis: Air Location

In intestinal pneumatosis, the air is located extraluminally within the bowel wall itself, not intraluminally. 1, 2

Definition and Characteristics

Intestinal pneumatosis (PI) is defined as the presence of extra-luminal gas confined to the bowel wall, representing gas that has dissected into the wall layers of the intestine 1
This condition should be distinguished from intraluminal air, which is the normal presence of gas within the hollow lumen of the intestinal tract 2
Pneumatosis can manifest as linear gas tracking along the bowel wall or as cystic collections of gas within the intestinal wall layers 3

CT scan is the most sensitive imaging modality for detecting intestinal pneumatosis, clearly showing gas within the bowel wall rather than in the lumen 4
On CT, pneumatosis appears as gas tracking within the bowel wall, which may be linear or bubble-like in appearance 4
Ultrasound may show pneumatosis as echogenic reflections within the bowel wall, though it is less sensitive than CT 4
Plain radiographs can sometimes detect pneumatosis but are less sensitive than CT for distinguishing between intraluminal and extraluminal air 4

Intestinal pneumatosis can occur as a result of colonoscopy, where mucosal injury and intraluminal pressure may dissect air inside the bowel wall 4
This condition may represent either a benign finding or indicate a potentially life-threatening condition such as bowel ischemia or perforation 5, 6
When pneumatosis is accompanied by pneumoperitoneum (free air in the peritoneal cavity), it may indicate rupture of the subserosal cysts into the peritoneal space 5
The presence of pneumatosis with portal venous gas is particularly concerning for bowel ischemia 6

Air can dissect into the bowel wall through mucosal defects or increased intraluminal pressure 4
In some cases, pneumatosis may extend beyond the bowel wall into adjacent structures such as the mesentery or even the greater omentum 6
Pneumatosis cystoides intestinalis is a specific subtype characterized by multiple gas-filled cysts in the submucosa and subserosa of the intestinal wall 3

The clinical management of intestinal pneumatosis depends on the underlying cause and the patient's clinical status 7
CT findings of pneumatosis with distant intraperitoneal free air often indicate perforation requiring surgical exploration 7
Laboratory tests including white blood cell count and C-reactive protein should be obtained to assess for inflammatory markers that might indicate infection or ischemia 4, 8
Not all cases of pneumatosis require surgical intervention; stable patients without signs of peritonitis may be managed conservatively with close monitoring 5, 6

Distinguishing between benign pneumatosis (pneumatosis cystoides intestinalis) and life-threatening pneumatosis is crucial for appropriate management 3
Additional CT findings such as bowel wall thickening, mesenteric stranding, portal venous gas, and free fluid may suggest a more concerning etiology requiring urgent intervention 2, 3
In cases where pneumatosis is found incidentally in an otherwise stable patient, conservative management with close observation may be appropriate 6