Air in the lesser sac

Clinical History

A 60-year-old male patient, previously autonomous, was brought unconscious to the emergency department and an acute intra-cerebral haemorrhage was diagnosed on CT.
Bloody drainage was also observed in the nasogastric tube. On upper endoscopy a deep bleeding ulcer was seen in the gastric lesser curvature. An abdominal CT was obtained.

Imaging Findings

The abdominal CT showed the presence of anomalous gas in the lesser sac, with communication with the gastric lumen consistent with a contained perforation at the level of the ulcer observed on upper endoscopy, in the lesser gastric curvature. The perforation was not apparent on the upper endoscopy.
As an incidental finding, an important anatomic arterial variant was detected: the presence of a coeliacomesenteric trunk.

Discussion

Gastrointestinal (GI) tract perforation is an emergency condition that usually requires surgery. CT is the most useful imaging modality for identifying the presence, site and cause of the GI tract perforation.

Direct CT findings of GI tract perforation include discontinuity of the bowel wall and the presence of extraluminal air. Indirect CT findings include bowel wall thickening, abnormal bowel wall enhancement, abscess and an inflammatory mass adjacent to the bowel [1-3].

The most frequent causes of gastric perforations include peptic ulcer disease and ulcerated malignancies (adenocarcinoma, lymphoma) [2]. Peptic ulcer disease is rarely diagnosed on CT, unless the ulcer is very large or has penetrated or perforated [3].

In the present case, a focal gastric wall discontinuity was obvious and this sign is highly specific for perforation. However, it is only seen in a small percentage of gastrointestinal tract perforations, being more often present in the upper tract. The relatively infrequent detection of this finding is partly due to the small size of the lesion [2].

Additionally, presence of free air in the lesser sac is commonly due to posterior perforation of the stomach or duodenum. Less commonly rupture of the lower oesophagus or transverse colon can present with free air in this location [1-3].

This patient was managed surgically, with suture of the perforation, as most patients with a perforated ulcer are. Preoperative confirmation of the ulcer location can impact the surgical technique [1, 2].

Furthermore, the radiologist should analyse the splanchnic vasculature, because the presence of anatomic variants could also affect surgery approach.

In this case, a rare arterial variant was detected. The coeliac trunk and superior mesenteric artery were noted to have a common anatomic origin from the aorta (Fig. 2). This variation is called common coeliacomesenteric trunk and accounts for less than 1% of all abdominal vascular anomalies [4].

Differential Diagnosis List

Final Diagnosis

Gastric contained perforationCoeliacomesenteric trunk

URL:	https://www.eurorad.org/case/13448
DOI:	10.1594/EURORAD/CASE.13448
ISSN:	1563-4086