CT appearance of afferent loop obstruction.

Obstruction of the afferent loop may develop in patients who have had a Billroth type II gastrojejunostomy. This obstructed loop has a characteristic but initially confusing computed tomographic appearance that might be mistaken for multiple peripancreatic cystic masses. Three cases of afferent loop obstruction due to gastric carcinoma are reported. In each case, the length of the jejunal segment incorporated into the afferent loop determined the number of cystic masses evident at each scan level. Recognition of the typical anatomic configuration and uniform size of these cystic masses is key to the correct diagnosis.