Efferent loop syndrome is one of two "loop syndromes." These can happen after some types of gastric surgery where a loop of small intestine has been brought up and is then connected to the stomach. In an efferent loop syndrome, the small intestine leading away from the stomach becomes blocked.

The other type of loop syndrome is afferent loop syndrome, and it involves the loop of small intestine that is traveling to the stomach. It is more common. Efferent loop syndrome is quite rare. Surgeons have improved gastric surgery, so both types of loop syndromes are now less common.

Efferent loop syndrome more often occurs in the first few weeks after gastric surgery. It often happens because of swelling and kinking at the surgical site. This causes a blockage. This is because of scarring or poor reconstruction during weight-loss surgery. When it happens later on, the cause may be from narrowing, sores (ulceration), or scarring. It can also occur due to a hernia of the small bowel that causes a blockage. In some cases, part of your intestine may slide inside another part of the intestine (intussusception). That may also cause a blockage.

Because of efferent loop syndrome, digestive fluids such as bile and other enzymes build up in the intestines and start to cause problems. The intestinal wall sometimes breaks (ruptures), but this is rare.

Your symptoms may include:

• Extreme stomach pain that's worse when you lie down. Often, cramping happens with the pain.
• Nausea.
• A bloated stomach and pain that's eased only by vomiting.
• Vomiting large amounts of green digestive fluid (bile).

If your doctor thinks that you have efferent loop syndrome because of gastric bypass surgery, they will look for the blockage. They may do a physical exam, upper gastrointestinal X-ray, or a CT scan. Your doctor may use a thin, lighted tube with a tiny camera at the end (endoscope) to confirm the diagnosis. They will put the scope through your mouth and down into your intestines.

Surgery is often needed to fix efferent loop syndrome and restore the intestines to healthy working order. Depending on how severe the efferent loop syndrome has become, the surgeon may have to repair lesions and close any defects to repair the intestine. They may need to make changes or repairs to the gastric surgery itself.

If the cause is swelling or scarring, you may need to limit food and fluids. You many also need to take medicines to reduce stomach acid. You may need to use a nasogastric tube to remove the buildup of fluids.

Contact your doctor right away if you have any of the symptoms of efferent loop syndrome listed above any time after weight-loss surgery.

• In efferent loop syndrome, part of the small intestine becomes blocked. Efferent loop syndrome is quite rare.
• When efferent loop syndrome happens, it's usually within the first few weeks after gastric bypass surgery.
• Common symptoms are extreme stomach pain, nausea, swollen stomach, and vomiting large amounts of bile.
• Doctors will use an endoscope passed through your mouth and into your intestines to confirm the diagnosis.
• The treatment may involve medical therapy, but it is usually surgery.
• Contact your doctor right away if you have any of the above symptoms after weight-loss 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.