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
- Patient positioned prone or semiprone (RAO) on fluoroscopy table.
- Endoscope advanced through mouth → esophagus → stomach → duodenum.
- Cannulation of the ampulla of Vater performed under direct endoscopic view.
- Iodinated contrast medium injected retrograde into biliary and/or pancreatic ducts.
- Fluoroscopy and spot images obtained to evaluate ductal system.
- 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.