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. 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.

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, intestinal wall breaks (ruptures).

You may have the following symptoms:

  • Extreme stomach pain that's worse when you lie down. Often cramping happens with the pain.
  • Nausea
  • 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 or "limb" of the small intestine becomes blocked. Efferent loop syndrome is quite rare.
  • When efferent loop syndrome happens, it is 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.


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