bubble_chart Overview

Afferent Loop Syndrome refers to the stasis of bile or pancreatic juice caused by obstruction of the afferent loop after Billroth II gastrectomy and antecolic anastomosis. There are two types: acute and chronic obstruction. The former is mostly complete obstruction, while the latter is reversible and partial obstruction.

bubble_chart Etiology

Acute afferent loop obstruction usually occurs within 24 hours after surgery, but it can also develop days or even years postoperatively. The obstruction may be partial or complete, intermittent or permanent. After Billroth II surgery, approximately 1% of patients experience obstruction near the gastrojejunal site of the afferent loop, with antecolic anastomosis being more common than retrocolic anastomosis. In antecolic anastomosis, if the afferent loop is left too long, it can become trapped behind the efferent loop while passing through the space between the mesentery of the efferent jejunal loop and the transverse mesocolon, leading to strangulated obstruction. If the gastrojejunal anastomosis or the duodenal-jejunal flexure forms a crossed position—with the afferent loop behind and the efferent loop in front—the mesentery of the latter may compress the afferent loop, causing closed-loop obstruction of the afferent jejunal loop. In retrocolic anastomosis, the afferent loop may retract into the opening of the transverse mesocolon, resulting in obstruction.

Due to the blockage of pancreatic juice and bile outflow in the afferent loop, pancreatic juice and bile accumulate, causing acute dilation of the afferent loop and severe epigastric pain that radiates to the interscapular region. Frequent vomiting occurs, but the volume is small, and the vomitus does not contain bile; symptoms are not relieved after vomiting. Significant tenderness is present in the epigastrium, and sometimes the dilated afferent loop can be palpated. Excessive fluid accumulation in the afferent loop may lead to reflux of intestinal fluid into the pancreatic duct, increasing the risk of acute pancreatitis, with a rapid rise in serum amylase levels. In cases of complete obstruction, the dilated afferent loop may undergo necrosis and perforation, leading to peritonitis and shock.

Chronic efferent loop obstruction typically develops weeks after surgery, but it can also occur a year or more postoperatively. This type is more common after Billroth II surgery when an angulation exists, particularly in antecolic anastomosis. It is caused by the afferent loop protruding into the space behind the gastrojejunal anastomosis, though a few cases result from adhesions or jejunojejunal intussusception. When bile and pancreatic juice accumulate in the afferent loop, causing dilation, intestinal peristalsis is stimulated, leading to the discharge of accumulated fluid into the stomach and resulting in vomiting of bile-containing liquid.

bubble_chart Diagnosis

Clinical manifestations The patient typically presents with strangulated high jejunal obstruction, often occurring about 1 hour after meals, suddenly experiencing projectile vomiting of bile-stained fluid. Before vomiting, there is often nausea, upper abdominal distension and fullness pain, radiating to the back. Symptoms usually subside after vomiting, only to recur after the next meal. Physical examination reveals tenderness in the upper abdomen, and sometimes a dilated afferent loop can be palpated in the upper right abdomen.

Diagnosis After Billroth II gastrectomy and antecolic anastomosis, combined with clinical manifestations, and performing tests such as Dahlgren and Jordan, a diagnosis can be made.

bubble_chart Treatment Measures

Acute afferent loop syndrome should be treated with early surgery; for chronic cases, surgical intervention is necessary when drug therapy is ineffective.