Small bowel ischaemia with intestinal and portomesenteric pneumatosis

Clinical History

Diabetes mellitus and arterial hypertension. Right iliopopliteal by-pass 7 years ago and left iliac stent 4 years ago. 24 hours of abdominal pain, with no prior abdominal pain, mainly in right lower quadrant, and abdominal distention. Nausea, normal stools. No fever, no leukocytosis.

Imaging Findings

An abdominal ultrasound (US) examination discovered multiple echogenic foci in the liver parenchyma, including subcapsular region (Fig. 1a). Further, several echogenic artifacts with hepatopetal direction were depicted within the main portal vein (Fig. 1b).
These imaging findings and the clinical data led to the suspicion of portomesenteric gas due to intestinal ischaemia. A subsequent contrast enhanced computed tomography (CT) demonstrated tiny bubbles within the small bowel wall (Fig. 2), a so-called "pneumatosis intestinalis". In addition, intestinal dilatation and faint wall enhancement were noticed in the affected jejunal loops. The stomach was dilated, while the proximal jejunum, ileum and colon appeared normal. Gas bubbles were also visible in both small peripheral mesenteric veins (Fig. 3a) and in the main mesenteric (Fig. 3b, 3c) and portal vein. The superior mesenteric artery and its branches showed intense ateromatosis (Fig. 4), explaining the cause of a deficient blood supply of jejunal bowel loops. Finally, in agreement with US findings, gas bubbles were seen in intrahepatic portal vein branches, mainly in subcapsular vessels of the left liver lobe (Fig. 5).
Laparotomy with resection of the ischaemic bowel segment was carried out, but no revascularisation of the occluded artery was performed. The initial response was good, although six days later the patient suffered from another episode of abdominal pain. A second laparotomy was performed and intestinal ischaemia distal to the anastomosis was detected. In spite of the resection of the ischaemic bowel loop, the patient died 24 hours later, seven days after the onset of abdominal pain.

Discussion

Pneumatosis intestinalis is a rare condition, defined as presence of gas bubbles within the bowel wall. A wide range of diseases may cause this radiological finding, from benign conditions to lethal processes. Pneumatosis intestinalis is often associated with mesenteric ischaemia, but other etiologies do occur. Causes of pneumatosis intestinalis can be classified into the following groups: a) mucosal erosion in bowel ischaemia (embolic or thrombotic origin, the case presented is an example of the latter) or perforation (peptic, neoplastic); b) mucosal disruption in ileus (paralytic or mechanic) or iatrogenic state (after gastrostomy, colonoscopy, enema, ...); c) infectious diseases (necrotizing enterocolitis, abdominal abscesses, ...); d) increased mucosal permeability (corticoid and cytostatic drugs); e) obstructive pulmonary disease.
The differential diagnosis of gas with a branching pattern in the liver parenchyma includes aerobilia and portal venous gas. Hepatic portal vein gas, due to hepatopetal flow, is characteristically associated with peripheral gas lucencies and noted within 2 cm of the liver capsule. By contrast, aerobilia - due to hepatofugal flow - is located more centrally in direction of the liver hilus.
CT findings in intestinal ischemia depend on the mechanism of impaired blood supply (arterial embolism, arterial thrombosis, venous thrombosis; hypoperfusion as a result from a combination of low flow and vasoconstriction). They include increased or lack of bowel wall contrast enhancement, contrast filling defect in mesenteric vessels, bowel distention, mesenteric fat stranding, ascites, pneumatosis intestinalis, and portomesenteric venous gas.
CT is considered as imaging modality of choice in suspected mesenteric ischaemia.
Teaching points:
a) Pneumatosis intestinalis is often related to mesenteric ischaemia.
b) Aerobilia and portal venous gas show a different distribution in the liver, the latter being more peripheral/subcapsular.

Differential Diagnosis List

Final Diagnosis

Intestinal ischemia with pneumatosis intestinalis and pneumoportogram

URL:	https://www.eurorad.org/case/9093
DOI:	10.1594/EURORAD/CASE.9093
ISSN:	1563-4086