Afferent Loop Syndrome

Afferent loop syndrome (ALS) is an uncommon mechanical complication that can occur after various upper gastrointestinal procedures involving anastomosis of the stomach or esophagus to the jejunum. Classically described with Billroth II gastrojejunostomy, other common procedures such as Roux-en-Y gastrojejunostomy, Roux-en-Y esophagojejunostomy, and the Whipple procedure are also associated with afferent loop syndrome.[1] Following a Billroth II reconstruction, the afferent loop is comprised of the gastric/duodenal stump, duodenum, and the short segment of jejunum proximal to the gastrojejunostomy. Following Roux-en-Y gastric bypass, the biliopancreatic limb remains connected to the remnant stomach and is anastomosed distally via jejunojejunostomy. The afferent limb transfers bile, pancreatic, and proximal intestinal secretions distally towards the anastomosis (gastrojejunostomy in Billroth II/Whipple procedures and jejunojejunostomy in Roux-en-Y). The efferent loop receives and transfers the ingested food and liquids. Afferent loop syndrome is defined by a distal obstruction causing distension of the afferent limb secondary to the accumulation of bile, pancreatic fluid, and proximal small bowel secretions.[2]