Retroanastomotic hernia after gastrojejunostomy: US and CT findings with an emphasis on the whirl sign.

BACKGROUND: We reviewed ultrasound (US) and computed tomographic (CT) findings of retroanastomotic hernia and established whether such findings are characteristic of retroanastomotic hernia in patients who have undergone gastrojejunostomy.

METHODS: During a recent 10-year period, we encountered 13 consecutive cases of retroanastomotic hernia. Of the patients involved, 11 underwent US, 10 underwent CT, and three underwent small bowel followthrough imaging. The US and CT scans were retrospectively reviewed to determine abnormal findings. Surgical proof was available in all cases.

RESULTS: The efferent loop was herniated through the defect created behind the anastomosis in 10 cases, the efferent and afferent loops in two cases, and the afferent loop in one case. Retroanastomotic hernia was prospectively suggested in 12 of these 13 cases. Among the 10 cases of efferent loop herniation, US and CT signs of retroanastomotic hernia included whirling of mesenteric vessels, jejunal loops, and mesentery in the periumbilical abdomen (10 of 10); mural thickening of herniated bowel loops (six of 10); dilatation of herniated bowel loops (four of 10); decreased peristalsis of herniated bowel loops on US (three of nine); and decreased contrast enhancement of herniated bowel loops on CT (one of seven). In one case, US and CT signs of retroanastomotic hernia of the afferent loop included its dilatation and whirling of a short length of afferent loop behind the anastomosis. In two cases, US and CT signs of retroanastomotic hernia of the afferent and efferent loops included findings of afferent and efferent loop herniations. Three of 13 cases had reversible bowel ischemia, and one had bowel necrosis.

CONCLUSION: Retroanastomotic hernia is an important condition, and the US and CT findings we have described might suggest its diagnosis.