Afferent loop syndrome is a problem that can occur after some stomach surgeries when something traps the flow of digestive juices. It can happen after surgeries when the first part of the small intestine is brought up and connected to the stomach. The area of connection is called an anastomosis.

Fluids from the pancreas and bile duct flow through the first part of the small intestine up to the stomach. If a partial or complete blockage happens in this part of the small intestine (also known as the afferent limb of the small intestine), problems can occur. Afferent loop syndrome can cause belly or back pain, nausea, and vomiting. If the obstruction is severe, it could affect the pancreas, the bile duct, liver, the duodenum, and the afferent limb.

After surgery, your bile and digestive fluids enter the afferent limb. The fluids then flow toward the upper stomach. They need to pass through the connection (anastomosis) and then enter the part of the small intestine that empties from the stomach (called the efferent limb). This syndrome occurs when something traps the flow of these juices in the afferent limb. Fluid pressure builds up in the afferent limb and causes discomfort and nausea. If the pressure builds up, the bile and pancreatic fluid may then suddenly empty into the upper stomach. This can cause symptoms, such as vomiting.

Common causes of the syndrome include:

• A problem with the connection between the small intestine and the stomach. This could be an ulcer at the connection. There might be a narrowing that has caused the blockage.
• Twisting of the afferent limb.
• Scar tissue (adhesions) near the afferent limb after surgery.
• Cancer that blocks the afferent limb.
• Foreign bodies, such as a bezoar, a mass of impacted food.

The syndrome can occur 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.

The most common symptoms are:

• Abdominal pain, especially in the upper part of your belly.
• Nausea and fullness, especially after eating.
• Sudden, severe vomiting of fluid with bile in it that suddenly eases the pain.
• Weight loss because of pain after eating.

If the syndrome happens early after stomach surgery, there may be a sudden onset of upper belly pain. Nausea and vomiting may occur. If a leak from the connection occurs, then peritonitis or shock may result. This causes a fast heart rate and lower blood pressure. Lab tests will be done. An abdominal CT scan will be used to help diagnose the condition. The scan may show the swollen afferent limb. Surgery may be needed to relieve the obstruction.

With the chronic type of the syndrome, you may be diagnosed with an abdominal CT scan. An upper endoscopy may also be used to look for an obstruction, an ulcer, or a tumor.

For acute afferent loop syndrome, emergency surgery may be needed. This is to prevent a leak at the connection at the staple line of the duodenum, ischemia, or perforation of the afferent limb. The type of surgery will depend on what's causing the blockage. In some cases, the connection may need to be redone. Scar tissue may need to be divided, freeing up the blockage.

For chronic afferent loop syndrome, a nasogastric tube might be placed to remove fluids from the stomach and the afferent limb. Supplemental nutrition may be needed if there has been a lot of weight loss. Antibiotics may be recommended if there is bacterial overgrowth in the partially obstructed afferent limb. Upper endoscopy helps to diagnose any narrowing at the connection.

Surgery is most likely recommended if there is no cancer present. Procedures may include revising the small intestine loop, remaking the connection, or making another connection between the afferent limb and the efferent limb. If cancer is present, surgery may not be the best approach. Instead, palliative procedures might be considered with endoscopic balloon dilation, stent placement, or drains.

Call your doctor right away if you have symptoms of afferent loop syndrome, especially after recent stomach surgery.

• Afferent loop syndrome is a problem that can occur after some kinds of stomach surgery.
• It occurs when something traps the flow of digestive juices in the afferent limb. Fluid pressure builds up in the limb and causes discomfort and nausea.
• Common symptoms are abdominal pain, nausea, and sudden vomiting of fluid with bile in it.
• Treatment is almost always surgery. For acute afferent loop syndrome, you may need emergency surgery.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions, especially after office hours or on weekends and holidays.