Efferent Loop Syndrome
What is efferent loop syndrome?
Efferent loop syndrome is one of two "loop syndromes" that can happen after some types
of gastric surgery. In a loop syndrome, part of the small intestine becomes blocked.
The other type of loop syndrome is afferent loop syndrome, which is more common. Efferent
loop syndrome is quite rare. Surgeons have improved gastric surgery, so both types
of loop syndromes are now less common.
What causes efferent loop syndrome after gastric surgery?
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 the weight-loss
surgery. When it happens later on, the cause may be from narrowing, sores (ulceration),
or scarring. In some cases, part of your intestine may slide inside another part of
the intestine (intussusception). This is caused by an efferent loop blockage.
What are the symptoms of efferent loop syndrome?
Because of efferent loop syndrome, digestive fluids such as bile and other enzymes
build up in the intestines and start to cause problems. Rarely, the intestinal wall
You may have the following symptoms:
Extreme stomach pain that's worse when you lie down. Often cramping happens with the
Bloated stomach and pain eased only by vomiting
Vomiting large amounts of green digestive fluid (bile)
How is efferent loop syndrome diagnosed?
If your healthcare provider thinks you have efferent loop syndrome because of gastric
bypass surgery, he or she may do a physical exam, upper gastrointestinal X-ray, or a
CT scan to look for the blockage. Your healthcare provider may use a thin, lighted
tube with a tiny camera at the end (endoscope) to confirm the diagnosis. He or she
will put the scope through your mouth and into your intestines.
How is efferent loop syndrome treated?
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.
He or she 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, and use a nasogastric tube to
remove the buildup of fluids.
When should I call my healthcare provider?
Call your healthcare provider right away if you have symptoms of efferent loop syndrome
any time after your weight-loss surgery.
Key points about efferent loop syndrome
In efferent loop syndrome, a portion 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.
Healthcare providers will use an endoscope passed through your mouth and into your
intestines to confirm the diagnosis.
The treatment may involve medical therapy or surgery.
You should contact your healthcare provider immediately if you have any of the above
symptoms after your weight-loss surgery.
Tips to help you get the most from a visit to your healthcare provider:
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 provider tells
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 provider 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
Know how you can contact your provider if you have questions