What is the second most common site where the common bile duct (CBD) opens into the gastrointestinal tract?

Second Most Common Site of Common Bile Duct Opening in the Gastrointestinal Tract

The second most common site where the common bile duct (CBD) opens into the gastrointestinal tract is the duodenal bulb (first part of duodenum). 1

Normal Anatomy and Variations

• The CBD normally opens at the ampulla of Vater in the second portion of the duodenum, which is the most common location 2
• Ectopic openings of the CBD are rare congenital anomalies but have significant clinical implications 1
• According to case series data, the distribution of ectopic CBD openings shows the duodenal bulb as the second most common site after the normal location 1

Distribution of Ectopic CBD Openings

• First portion of duodenum (duodenal bulb): second most common site, accounting for approximately 36% of ectopic openings 1
• Third portion of duodenum: third most common site 1
• Stomach: rare site for ectopic CBD opening 1
• Pancreatic duct: can occur in cases of double common bile duct 3, 4

Clinical Significance

• Ectopic openings of the CBD are associated with higher rates of:

  • Choledocholithiasis (biliary stones) 1, 5
  • Cholangitis 1
  • Acute pancreatitis 1
  • Duodenal deformity or stenosis 5

• The location of ectopic CBD openings has important implications for:

  • Surgical planning and potential complications 3
  • Endoscopic access and treatment approaches 5
  • Risk of associated malignancies 4

Diagnostic Considerations

• Ectopic CBD openings may be suspected on transabdominal ultrasound but are typically confirmed by:

  • Endoscopic retrograde cholangiopancreatography (ERCP) 3, 1
  • Magnetic resonance cholangiopancreatography (MRCP) 6

• Awareness of this anatomical variation is crucial for endoscopists and surgeons to avoid complications during procedures 3, 5

Treatment Implications

• Endoscopic treatment is feasible in patients with ectopic CBD openings but may require multiple procedures 5
• Surgical intervention may be necessary in cases where endoscopic management fails 5
• Long-term follow-up is important due to the risk of recurrent biliary problems 5

Special Considerations

• Double common bile duct (DCBD) is a rare anomaly where two common bile ducts exist, with one opening at the normal location and the other (accessory CBD) opening at an ectopic site 3, 4
• The site of the accessory CBD opening has important implications for associated pathologies and treatment approaches 4
• Middle-aged males with duodenal deformity/stenosis should be evaluated for possible ectopic CBD opening 5