Gallstone disease affects over 20 million Americans. Among patients with gallbladder disease, the prevalence of choledocholithiasis (stones in the bile duct) is estimated to be 10-20%. Endoscopic retrograde cholangiopancreatography (ERCP) is considered the standard of care for removing stones in the bile duct utilizing a variety of conventional methods including biliary sphincterotomy, sphincteroplasty, extraction balloon, retrieval basket, and mechanical lithotripsy. After removal of stones from the bile duct, an occlusion cholangiogram is usually performed to confirm complete bile duct clearance. However, cholangiogram can miss residual stones in 11- 30% of cases - especially in the setting of a dilated bile duct, large stones, severe pneumobilia, juxtapapillary diverticulum, primary sclerosing cholangitis, and after lithotripsy (mechanical, electrohydraulic, or laser). The approach to patients with choledocholithiasis requires careful attention because missed bile duct stones can cause recurrent biliary symptoms, pancreatitis, cholangitis, and has significant cost implication with the need for repeat imaging and/or procedures.

Peroral cholangioscopy (POC) provides direct visualization of the bile duct during ERCP and its benefits are well documented in numerous published studies. POC has been described for therapy of difficult to remove biliary stones utilizing electrohydraulic lithotripsy or laser lithotripsy with success rates of >90%. POC has also been used for evaluation of indeterminate filling defects and to assess for residual stones missed with cholangiogram. In a multicenter study evaluating POC for a variety of indications, 11% (7/66) of patients had bile duct stones identified only by POC that were missed on ERCP. In a study of patients with primary sclerosing cholangitis, 30% (7/23) of patients were found to have stones with POC that were missed with cholangiography. Takao et al. assessed residual bile duct stones found with POC in comparison to balloon-cholangiography; they found that 24% (26/108) of patients had residual stones seen with POC that were missed with balloon-cholangiography.

Although POC has been available for over thirty years, it has not become a widespread technique due to the fact that traditional cholangioscopes are fragile, cumbersome to use, and usually require two endoscopists to perform the procedure. A recent single operator semi-disposable cholangioscope, SpyGlass (Boston Scientific, Natick, Massachusetts), has addressed those concerns and has been shown in a studies to be a useful tool in visualizing the bile ducts and performing therapeutic maneuvers for biliary stones. Both ERCP and Cholangioscopy are standard of care procedures to treat gall stones.

The primary goal of the study is to assess if POC will enhance the diagnostic yield in the detection of residual biliary stones that are missed during conventional ERCP. Residual bile duct stones can especially be seen in the setting of bile duct dilation, history of recurrent abnormal liver function tests, and after lithotripsy (mechanical, electrohydraulic, or laser). Missed biliary stones can lead to recurrent biliary symptoms, pancreatitis, and cholangitis. POC after conventional ERCP can be a useful diagnostic tool to confirm complete extraction of bile duct stones, and thus lead to decreased morbidity and decreased cost by avoiding unnecessary tests and repeat procedures.

Inclusion Criteria:

1. Patient receiving ERCP as standard of care for suspected or documented choledocholithiasis as assessed by one or more of the following:

   1. Abnormal imaging on ultrasound, endoscopic ultrasound (EUS), CT scan, or MRCP suggestive of choledocholithiasis
   2. Clinical signs and symptoms suggestive of choledocholithiasis such as jaundice, abdominal pain, pruritis, pancreatitis, and/or cholangitis
   3. Abnormal liver function tests suggestive of choledocholithiasis (eg: serum bilirubin > 1.5 and/or elevated alkaline phosphatase levels)

2. In addition to one or more of the above inclusion criteria, patient must also satisfy one or more of the following:

   1. Mechanical lithotripsy, electrohydraulic lithotripsy, or laser lithotripsy performed for therapy of bile duct stones.
   2. Bile duct > 12mm on prior tests (any portion of duct)
   3. History of recurrent abnormal LFTs with negative cholangiogram.
   4. Positive EUS or MRCP for biliary stones with a negative cholangiogram

Exclusion Criteria:

1. Patients less than 18 years of age.
2. Patients not undergoing ERCP as their standard of care.
3. Patients who had the following surgeries - Billroth II surgery, Roux-en-Y Gastric bypass surgery, and Whipple's surgery.

Patients who are undergoing ERCP as their standard of care for treatment of their gall stones.

Individual participant data will not be shared.