Afferent loop syndrome is a problem that can occur after some kinds of stomach surgery. It’s also known as afferent limb syndrome. 

The small intestine loop has 2 loops. The loop going to the upper stomach is the afferent loop. The loop carrying food away from the stomach is called the efferent loop. Afferent loop syndrome can occur after some types of gastrojejunostomy. One type is the Billroth II gastrectomy. During the procedure, a surgeon will remove or bypass the lower part of the stomach and attach the remaining upper part of the stomach to a loop of small intestine. The new connection is the anastomosis.