ERCP Procedure: Contrast & Safety for Rad Techs

What Is ERCP?

ERCP — endoscopic retrograde cholangiopancreatography — is a combined endoscopic and fluoroscopic procedure used to diagnose and treat problems of the bile ducts and the pancreatic duct. A thin flexible duodenoscope (an endoscope with a side-viewing lens) is passed through the mouth, stomach, and into the duodenum, where the operator finds the ampulla of Vater (the major duodenal papilla). A small catheter is then inserted through the scope into the ampulla, and iodinated contrast is injected retrograde (backward, against the normal direction of bile flow) so that fluoroscopy shows the biliary tree and pancreatic duct filling with contrast.

The radiologic technologist's role centers on fluoroscopy: setting up the imaging chain, positioning the patient, acquiring real-time fluoroscopy and spot radiographs, and keeping dose as low as reasonably achievable (ALARA). ERCP is a high-yield topic in fluoroscopy and contrast-media review for the ARRT exam.

Why Order ERCP? (Indications)

Most ERCPs performed today are therapeutic. Diagnostic-only ERCP is now uncommon because MRCP (magnetic resonance cholangiopancreatography) images the bile and pancreatic ducts noninvasively. ERCP is ordered when an intervention is planned or when a duct must be opacified and treated during the same session:

• Choledocholithiasis — stones in the common bile duct, extracted with a retrieval basket or balloon catheter, usually after an endoscopic sphincterotomy.
• Biliary obstruction or stricture — benign or malignant narrowing of the bile ducts, treated with stent placement or dilation.
• Malignant obstruction — from cholangiocarcinoma, pancreatic head cancer, or metastatic disease.
• Bile leak — for example after cholecystectomy or liver surgery.
• Sphincter of Oddi dysfunction — measured by manometry during ERCP.
• Pancreatic duct disease — chronic pancreatitis, pancreatic-duct stricture or stone, or a pancreatic leak.
• Suspected stones on other imaging — to confirm and remove them in one setting.

ERCP vs. MRCP vs. Other Imaging

Contrast Media in ERCP

The classic exam question: what contrast is used for ERCP? The answer is water-soluble iodinated contrast — typically a low-osmolality nonionic agent — diluted and injected through the cannulating catheter into the bile and pancreatic ducts.

Barium is never used. Barium sulfate suspension is designed for the lumen of the gastrointestinal tract and is retained in the abdomen if it escapes; injected barium is dangerous in the biliary or pancreatic ducts or in the peritoneal space. Because ERCP uses iodinated contrast, patients with a known iodinated contrast allergy are identified beforehand and observed for a reaction, and reaction-management supplies are handled the same way they are in other fluoroscopic rooms.

See Contrast Media in Radiology: Types, Administration, Adverse Reactions for the full breakdown of iodinated agents, osmolality, and adverse-reaction management.

Patient Preparation

Your ERCP prep checklist (the technologist helps confirm readiness and safety):

• NPO (fasting). The patient usually has nothing to eat or drink for roughly 6–8 hours before the procedure. An empty stomach reduces aspiration risk under sedation and keeps the duodenum clear.
• Blood thinners first. Anticoagulants and antiplatelet agents are typically stopped several days in advance — critical if a sphincterotomy is planned, because that step carries a bleeding risk.
• Coagulation and kidney status. Recent labs (INR/PT, platelet count) are reviewed, and renal function is checked because iodinated contrast is used.
• Allergy history. Disclose any allergy to iodinated contrast, latex, or medications.
• Medications and prior surgery. The team reviews the medication list and any prior GI/biliary surgery (a previous Roux-en-Y anastomosis makes cannulation harder and may need a specialized approach).
• Sedation planning. ERCP usually needs sedation (often propofol or conscious sedation) with cardiopulmonary monitoring.
• Pregnancy. If there is any chance of pregnancy, the team is told — fluoroscopy delivers ionizing radiation, and benefit/risk is weighed before proceeding.
• Consent. Informed consent is obtained for the endoscopic and fluoroscopic components and possible interventions.

Note on antibiotics: antibiotics are not routine for ERCP. They may be considered in selected high-risk patients (such as suspected biliary obstruction when complete drainage may not be achieved, or immunosuppression). This is a clinical decision, not a blanket protocol.

The ERCP Procedure — Step by Step

ERCP is performed by or under the direction of a qualified physician (often a gastroenterologist or interventional radiologist working in the fluoroscopy suite); the radiologic technologist assists with fluoroscopy, positioning, image acquisition, and radiation safety.

Step 1: Patient positioning and setup

The patient is positioned on the fluoroscopy table, typically supine (or prone/semi-prone depending on operator preference). The technologist confirms the fluoroscopy settings — pulsed mode, low frame rate, tight collimation — and positions the image intensifier or flat-panel detector over the right upper quadrant.

Step 2: Endoscopy to the duodenum

With the patient sedated, the side-viewing duodenoscope is passed through the mouth, esophagus, and stomach into the descending duodenum so the operator can see the ampulla of Vater.

Step 3: Cannulation of the ampulla

A small catheter (often with a guidewire inside) is inserted into the ampullary orifice. A free position in the duct is confirmed before any contrast is injected.

Step 4: Retrograde contrast injection under fluoroscopy

Key to the study: the operator injects water-soluble iodinated contrast through the catheter, which flows retrograde to fill the common bile duct and pancreatic duct. The technologist acquires fluoroscopy and spot images as the ducts fill, so strictures, stones, and dilation are documented. The pancreatic duct is opacified as well, and the operator may limit the number of pancreatic injections because they increase pancreatitis risk.

Step 5: Therapeutic maneuvers

Depending on the finding, the operator may perform a sphincterotomy (cutting the sphincter of Oddi), extract stones with a basket or balloon, dilate a stricture, place a stent, or insert a nasobiliary drain — all under fluoroscopic guidance so the technologist keeps the field tight and the radiation dose low.

Step 6: Final images

Post-intervention spot radiographs verify duct drainage, stone clearance, or stent position before the scope is removed.

Fluoroscopy Technique and Radiation Safety

• Pulsed fluoroscopy and the lowest practical frame rate keep beam-on time and dose down.
• Tight collimation to the region of interest; use last-image-hold and avoid unnecessary magnification.
• Shielding: lead apron, thyroid shield, and lead glasses/goggles for staff; wear your dosimeter; keep yourself out of the primary beam.
• Angulate or rotate the patient to project the duct system clear of overlapping structures.
• Mind the total fluoroscopy time and dose report — long therapeutic cases can accumulate dose; ALARA is a team responsibility.

See Fluoroscopy Procedures and Safety: A Complete Guide for Rad Techs for dose-management fundamentals, and Contrast Extravasation and Adverse Reaction Management for what to do when an iodinated reaction or extravasation occurs.

Contraindications and When to Hold

• Uncorrected severe coagulopathy or bleeding diathesis — a relative contraindication, especially against sphincterotomy.
• Severe acute pancreatitis — generally avoided unless a biliary emergency (cholangitis or obstruction) makes ERCP necessary.
• Hemodynamic instability or severe cardiopulmonary disease — high risk for sedation and endoscopy.
• Altered anatomy (such as a prior Roux-en-Y) doesn't forbid ERCP but makes cannulation technically harder and may require specialist techniques.
• Inability to consent.

Complications and Safety

• Post-ERCP pancreatitis (PEP) is the most common major complication. It is reported in about 2–10% of procedures, and a rate of roughly 4–8% appears in most prospective unselected series. Most cases are mild to moderate; a small minority are severe. Many centers lower the risk with rectal NSAIDs (such as indomethacin) and/or a prophylactic pancreatic-duct stent.
• Hemorrhage — most often bleeding after a sphincterotomy.
• Perforation — duodenal or biliary, uncommon but serious; signs include severe abdominal pain, fever, and free air.
• Cholangitis / sepsis — iodinated contrast injected into an obstructed duct must be promptly drained (stent or nasobiliary drain) or infection can follow.
• Iodinated contrast reaction — same recognition and management as elsewhere in the department.
• Sedation-related cardiopulmonary events (aspiration, arrhythmia, respiratory depression).
• Radiation exposure to patient and staff — minimized by the ALARA technique above.

Normal vs. Abnormal ERCP Findings

• Normal — contrast flows freely into a normal-caliber common bile duct and, when opacified, a normal pancreatic duct, with drainage into the duodenum.
• Choledocholithiasis — a stone appears as a filling defect in the contrast-filled duct; on fluoroscopy it is often a mobile, rounded lucency.
• Stricture / obstruction — a narrowing or an abrupt termination of the contrast column; the duct upstream may be dilated.
• Malignant obstruction — an irregular, rat-tailed or shouldered stricture, often in a dilated proximal duct.
• Bile leak — contrast pooling outside the expected duct contour.

Related Contrast Procedures

ERCP is one member of the battery of image-guided contrast studies a rad tech may assist with:

• Barium Studies: UGI, Small Bowel Follow-Through, and Barium Enema — GI lumen imaging with barium
• IVP and IVU Procedures: Excretory Urography for Rad Techs — iodinated contrast in the urinary tract
• Myelography: Procedure, Contrast & Safety for Rad Techs — subarachnoid iodinated contrast
• Arthrography Procedures: Shoulder & Knee Contrast Studies for Rad Techs — contrast inside joints

Frequently Asked Questions

What does ERCP stand for and what does it do?

ERCP stands for endoscopic retrograde cholangiopancreatography. A side-viewing endoscope is advanced to the duodenum, the ampulla of Vater is cannulated, and iodinated contrast is injected retrograde under fluoroscopy to image and treat the bile and pancreatic ducts.

What contrast is used for ERCP?

A water-soluble iodinated contrast agent — typically a low-osmolality nonionic agent — is injected through the catheter into the biliary and pancreatic ducts. Barium is never used because it is for the GI tract lumen and is dangerous if it enters a duct system or the abdomen.

Is ERCP diagnostic or therapeutic?

Today ERCP is primarily therapeutic: sphincterotomy, stone extraction, stricture dilation, and stent placement. For purely diagnostic duct evaluation, MRCP (magnetic resonance cholangiopancreatography) is usually the noninvasive first choice.

What is the most common complication of ERCP?

Post-ERCP pancreatitis is the most common major complication, reported in roughly 2 to 10 percent of procedures. Many centers reduce the risk using rectal NSAIDs and/or a prophylactic pancreatic-duct stent.

Why must the patient fast before ERCP?

Fasting (usually 6–8 hours of nothing by mouth) empties the stomach and duodenum, reduces the risk of aspiration under sedation, and keeps the field clear for endoscopy and contrast injection.

When is MRCP preferred over ERCP?

MRCP is preferred for noninvasive diagnostic imaging of the bile and pancreatic ducts because it uses no radiation and requires no instrumentation. ERCP is preferred when an intervention (such as stone removal or stenting) is needed, or when MRCP is not possible or not conclusive.