Cholangiography Using Carbon Dioxide Versus Iodinated Contrast in ERCP

It has been recommended that endoscopic retrograde cholangiopancreatography (ERCP) be
performed using carbon dioxide (CO2) instead of room air as the infused "air" or gas for
luminal insufflation for reasons of improved patient comfort and in case of procedural
adverse events (as CO2 is more quickly absorbed by the body and as it can be exhaled via the
lungs). Air cholangiograms are often incidentally visible on fluoroscopy (radiographically)
during ERCP prior to injection of iodinated contrast into the biliary tree. Despite the
information from an air cholangiogram being readily available in many instances, biliary
endoscopists and radiologists who read the fluoroscopic images taken during ERCP do not
usually comment or interpret the "air" or "CO2" cholangiograms. Consequently, very little
data is available on the topic of "air" or "CO2" cholangiography. As a contrast medium for
cholangiography, CO2 might be safer than iodinated contrast, which is the standard contrast
medium used during ERCP, as iodinated contrast cannot be easily absorbed by the body and as
it can be trapped proximal to obstructing biliary stones or strictures and lead to biliary
tract infection.

This is a prospective cohort study that will enroll patients undergoing ERCP for suspected
choledocholithiasis and/or biliary stricture(s). If they did not participate in this study,
these patients would still require an ERCP with CO2 used as the endoscopically insufflated
"air" medium. Enrolled patients will undergo an initial cholangiogram with CO2 (injected into
the bile ducts) utilizing both conventional fluoroscopy and digital subtraction fluoroscopic
imaging, followed by conventional cholangiography using iodinated contrast (injected into the
bile ducts). Digital subtraction fluoroscopic imaging is a commercially available setting on
certain fluoroscopy units that optimizes resolution with air or CO2 used as a contrast
medium. Findings on CO2 cholangiography will be compared to those obtained from
pre-procedural abdominal imaging along with the cholangiogram done using iodinated contrast
at the time of the ERCP procedures.

Inclusion Criteria:

- Patients 18 years of age or older

- Patients with choledocholithiasis, benign biliary strictures, malignant biliary
strictures

- Biliary pathology suggested or confirmed by imaging with abdominal ultrasonography, CT
scan, MRI/MRCP scan, or endoscopic ultrasonography (EUS)

Exclusion Criteria:

- Pregnancy (self reported)

- Presence of cholangitis before ERCP

- Prior history of surgery on the stomach or duodenum that precludes conventional ERCP
or prior biliary tree surgery (not including cholecystectomy)

- Failure to selectively cannulate the bile duct

- Life expectancy less than 30 days

- Prisoners

- Patients unable to give consent