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GI Studies

43 Endoscopic Retrograde Cholangiopancreatography (ERCP)

Anatomy

  • Liver (bile production)
  • Gallbladder (bile storage and release)
  • Hepatic ducts (right & left) → form common hepatic duct
  • Cystic duct → joins common hepatic duct to form common bile duct (CBD)
  • Pancreatic duct (duct of Wirsung)
  • Ampulla of Vater (hepatopancreatic ampulla) — junction of CBD and pancreatic duct
  • Sphincter of Oddi — controls flow of bile/pancreatic enzymes into duodenum
  • Duodenum — site of ductal entry

Indications, Contraindications, and Patient Preparation

Indications

  • Evaluation of biliary and pancreatic ducts
  • Detection/removal of gallstones or bile duct stones (choledocholithiasis)
  • Assessment of strictures, blockages, or leaks
  • Investigation of unexplained jaundice or abnormal liver function tests
  • Diagnosis and sometimes treatment of tumors (e.g., pancreatic or biliary carcinoma)
  • Stent placement for ductal obstruction

Contraindications

  • Known allergy to iodinated contrast media
  • Active pancreatitis (procedure may worsen inflammation)
  • Severe cardiac, respiratory, or bleeding disorders (relative contraindications)
  • Inability to tolerate sedation/anesthesia required for endoscopy

Patient Preparation

  • NPO for at least 8 hours prior (to empty stomach)
  • Remove dentures, jewelry, and restrict oral intake until after recovery
  • Conscious sedation or general anesthesia typically required
  • IV line established for medication and contrast administration
  • Explain exam: flexible endoscope passed through mouth → esophagus → stomach → duodenum, with catheterization of ducts

Procedure Overview

Technique

  1. Patient positioned prone or semiprone (RAO) on fluoroscopy table.
  2. Endoscope advanced through mouth → esophagus → stomach → duodenum.
  3. Cannulation of the ampulla of Vater performed under direct endoscopic view.
  4. Iodinated contrast medium injected retrograde into biliary and/or pancreatic ducts.
  5. Fluoroscopy and spot images obtained to evaluate ductal system.
  6. Interventions may follow (stone removal, sphincterotomy, stent placement).

Imaging & Projections

  • Prone / RAO position preferred — moves duodenal loop away from spine.
  • Spot fluoroscopic images of biliary tree and pancreatic ducts.
  • Images include: hepatic ducts, common bile duct, pancreatic duct, and ampulla of Vater.

Evaluation Criteria

  • Ductal system adequately filled with contrast
  • No filling defects (stones, tumors, strictures) unless pathology present
  • Contrast freely passes into duodenum

Procedure Adaptation

  • Pediatrics: Rare; occasionally performed for congenital anomalies or biliary atresia.
  • Geriatrics: More common due to gallstone disease and biliary obstruction.
  • Post-cholecystectomy patients: Used to detect residual stones or strictures.
  • Therapeutic role: Allows simultaneous treatment (stone retrieval, dilation, stent placement).

Exposure Factors & Technical Considerations

  • SID: 40 inches (fluoroscopy unit)
  • kVp: 70–80 (lower kVp for soft tissue and contrast visualization)
  • mAs: Low; fluoroscopy with spot imaging
  • Contrast: Water-soluble iodinated contrast only (never barium)
  • Collimation: Include entire biliary system and pancreatic ducts
  • Equipment: Combination of endoscope + C-arm fluoroscopy
  • Shielding: Standard protection where possible (though limited due to scope positioning)

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Hows & Whys of ERCP

Anatomy & Physiology

  • Why is the ampulla of Vater important in ERCP?
    It is the junction where the bile and pancreatic ducts empty into the duodenum; cannulation here is essential for duct access.
  • What role does the sphincter of Oddi play?
    It controls bile and pancreatic enzyme release; dysfunction may lead to obstruction or pancreatitis.

Contrast & Technique

  • Why is iodinated contrast used in ERCP?
    It is water-soluble and safe in case of leakage; it also mixes well with bile and pancreatic secretions for duct visualization.
  • Why is the patient positioned prone or RAO?
    This projects the duodenal loop away from the spine, improving visualization of the biliary tree.
  • Why is fluoroscopy essential during ERCP?
    It monitors duct filling, detects filling defects (stones, strictures), and guides therapeutic interventions.

Clinical & Safety Considerations

  • What are common complications of ERCP?
    Pancreatitis, infection, perforation, bleeding, or reaction to sedation/contrast.
  • Why is ERCP sometimes both diagnostic and therapeutic?
    It allows visualization of ducts and immediate treatment such as stone removal, sphincterotomy, or stent placement.
  • Why is NPO status required before ERCP?
    To ensure the stomach and duodenum are empty, reducing aspiration risk and allowing endoscopic access.
  • Why is patient monitoring required after ERCP?
    To detect complications (e.g., pancreatitis, bleeding, infection) and ensure sedation recovery.

 

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Radiographic Procedures Review Guide Copyright © 2025 by Carla M. Allen and Taylor M. Otto. All Rights Reserved.