Subjects will be enrolled at up to 20 clinical sites in the United States. Subjects who meet the eligibility criteria will be screened by the gastroenterology site for study participation at a baseline visit which will also include a blood test for renal function (eGFR), and will be evaluated on the randomized procedure day (CCE versus CTC) and again on the day of both the blinded and unblinded OC procedures. Telephone follow-ups will be conducted 5 - 9 days after the CCE/CTC procedure and 5 - 9 days after the unblinded OC procedure to assess subject well-being and capture any AEs, regardless of relationship to the CCE, CTC, or OC procedures.