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Afferent loop syndrome is a condition that occurs when there is an obstruction or blockage in the afferent loop, a part of the digestive system that connects the stomach to the small intestine. 

Afferent Loop Syndrome [MEDNOTES+MINDMAP]


  • Afferent loop syndrome is a condition that occurs when there is an obstruction in the afferent loop of the gastrointestinal tract.


  • It is a rare condition and the exact incidence is not known.
  • It can occur at any age, but is more commonly seen in middle-aged and elderly individuals.

Natural history:

  • The symptoms of afferent loop syndrome typically develop gradually over time.
  • The condition may resolve on its own, but in some cases, it may require medical intervention.


  • Afferent loop syndrome is typically classified based on the location of the obstruction in the afferent loop.
  • There are three main types of afferent loop syndrome: duodenal, jejunal, and ileal.
  • The stages of afferent loop syndrome include:
    • Stage 1: Mild symptoms, such as abdominal discomfort and bloating, with no weight loss.
    • Stage 2: Moderate symptoms, such as abdominal pain, weight loss, and diarrhea, with some malnutrition.
    • Stage 3: Severe symptoms, such as malnutrition, weight loss, and dehydration, with the possibility of complications.

  • Risk Factors

    • Previous abdominal surgery
    • Hernia
    • Adhesions
    • Crohn’s disease
    • Ulcerative colitis
  • Etiology/Causes

    • Obstruction of the afferent loop of the small intestine
    • The afferent loop is a portion of the small intestine that is surgically attached to the stomach to bypass a portion of the digestive system.
    • This can occur due to the presence of scar tissue or adhesions from previous surgery, a hernia, or inflammatory bowel disease.
  • Signs

    • Abdominal pain
    • Nausea
    • Vomiting
    • Constipation
    • Distention of the abdomen
  • Symptoms

    • Loss of appetite
    • Weight loss
    • Fever
    • Dehydration
    • Rapid heart rate
    • Low blood pressure


  • Histology/Microscopic Changes:
    • Obstruction of the afferent loop (bile duct) by a gallstone or other foreign body
    • Inflammation and swelling of the bile duct and surrounding tissue
    • Formation of scar tissue in the bile duct
  • Pathology/Pathogenesis:
    • The obstruction of the afferent loop leads to an accumulation of bile in the liver and gallbladder
    • This can cause inflammation and damage to the liver and gallbladder, leading to the formation of scar tissue
    • The scar tissue can cause the bile duct to narrow, leading to further obstruction and potentially causing jaundice
  • Diagnosis/Laboratory Diagnosis:
    • Physical examination, including palpation of the abdomen to feel for any abnormalities
    • Blood tests to check for elevated liver enzymes and bilirubin levels
    • Ultrasound or CT scan to visualize the bile duct and look for any abnormalities or blockages
  • Tests Required:
    • Endoscopic retrograde cholangiopancreatography (ERCP) to visualize the bile duct and remove any blockages
    • Percutaneous transhepatic cholangiography (PTC) to visualize the bile duct using a needle inserted through the skin
    • Surgery to remove the blockage and repair any damage to the bile duct

  • Contraindications:
    • Previous surgery on the afferent loop
    • Chronic inflammatory conditions
    • Previous radiation therapy
  • Associated with/Strongly Associated with:
    • Billroth II gastrectomy
    • Gastric bypass surgery
    • Peptic ulcer disease
  • Similar syndromes:
    • Dumping syndrome
    • Bowel obstruction
  • Prevention:
    • Avoiding large meals
    • Eating smaller, more frequent meals
    • Avoiding high-fat and high-sugar foods
    • Avoiding carbonated beverages
  • Treatment:
    • Antacids to neutralize stomach acid
    • Proton pump inhibitors to decrease stomach acid production
    • H2 receptor antagonists to decrease stomach acid production
    • Antibiotics to treat any infections
    • Surgery to remove part of the afferent loop if necessary

Dr. Arin Nandi

Passionate About Medical Science & Helping Future Doctors Achieve Top Ranks In Medical Exams. He is professionally a dentist as well as a public health expert from JIPMER working in department