Imaging description

Roux-en-Y gastric bypass (in which a small gastric fundal pouch is created and connected to the rest of the bowel by a Roux loop of jejunum, and the majority of the stomach is excluded from the normal flow of food) is currently one of the commonest and most successful surgical treatments for obesity in the United States [1,2]. The fluid-filled excluded stomach can mimic a rim-enhancing collection in the surgical bed on postoperative CT and may be mistaken for an abscess (Figure 55.1).

Importance

Misdiagnosis of the excluded stomach as an abscess could result in unnecessary workup, drainage, or even surgery.

Typical clinical scenario

This pitfall is most likely to result in misdiagnosis of abscess when a patient has a CT scan for fever or other symptoms in the early postoperative period after Roux-en-Y gastric bypass. In one study, the fundus of the excluded stomach mimicked a loculated fluid collection in 13 (18%) of 72 such patients [3].

Differential diagnosis

Roux-en-Y gastric bypass may be complicated by leak, abscess, or hematoma, so the correct identification of the excluded stomach is critical in the postoperative patient. The excluded stomach may be positively identified by the presence of gastric rugae and continuity with the duodenum (Figure 55.2).