After surgery, your bile and digestive fluids enter the afferent loop. The fluids flow toward the upper stomach. They need to pass through the anastomosis and then enter the efferent loop to help digest your food. Afferent loop syndrome occurs when something traps the flow of these juices in the afferent loop. Fluid pressure builds up in the afferent loop and causes discomfort and nausea. If the pressure builds up, the bile and pancreatic fluid may then empty into the upper stomach. This can cause symptoms such as vomiting.

                                                                                                                                              

Common causes of afferent loop syndrome include:
A problem with an anastomosis after gastrojejunostomy
Twisting of the afferent loop
Scar tissue near the afferent loop after surgery
Cancer that recurs and blocks the afferent loop

 

Afferent loop syndrome can occur anywhere from days to years after surgery. If it occurs soon after surgery, it’s called acute afferent loop syndrome. If it occurs weeks or years after surgery, it’s called chronic afferent loop syndrome.