The purpose of this study is to determine residual gastric volume and residual gastric pH in patients undergoing combined EGD and colonoscopy comparing the standard single dose prep with the split dose bowel preparation and same day bowel preparations.

The ASGE and ACG have developed standards for high-quality colonoscopy and ADR. Bowel cleansing must be optimal to enhance polyp detection and several studies have demonstrated the advantage of split dose or same day preparation as opposed to ingesting the preparation the day before. It is recommended that patients undergo split dosing of the bowel preparation or even same day bowel preparation for optimal cleansing. This is critical for high quality colonoscopy.

One of the risks associated with colonoscopy is pulmonary aspiration. Part of this risk may be related to retained gastric volume and gastric pH at the time of the endoscopic procedures. Aspiration pneumonia may be related to the acidity where more acidic aspirate may cause more severe respiratory compromise. In a recent article, Huffman supported the safety of split dose bowel preparation (4L bowel preparation) for outpatients undergoing colonoscopy. In this study it was/found that residual gastric volume in split dose preparations was higher than patients undergoing EGD alone but was not different from than in patients receiving bowel preparation the evening before. Early morning bowel preps for patients undergoing upper and lower endoscopies was not evaluated in this study. To our knowledge, the relationship of residual gastric volume in same day bowel preps has not been evaluated and has not been compared with the split dose bowel preps. A formal evaluation of difference in gastric acidity has not been evaluated in patients undergoing bowel prep for colonoscopy.

The study has a prospective observational design. The patients who have been already scheduled for a combined esophagogastroduodenoscopy and colonoscopy for their specific indications will be asked to be a part of this study. No additional intervention will be done other than the procedure they were already scheduled for. No specific interventions will be assigned to the subjects of the study. Outcomes will be assessed in pre-defined groups based on the bowel preparation taken by the patient.

The fluid is going to be collected in a suction container without solidifier material. Once the endoscopist enters the stomach all fluid will be suctioned which is part of the customary process of endoscopy. Once all fluid is aspirated, the container will be removed to empty the fluid into a measuring canister while the endoscopic procedure is continued and a container with solidifier material is instead connected to suction. The pH will be measured on the gastric fluid that was aspirated using a calibrated catheter pH device.

Inclusion Criteria:

• Adult patients (ages 18 and over) scheduled for elective non-emergency outpatient combined Esophagogastroduodenoscopy and colonoscopy procedures at CCF. No additional intervention will be done other than the procedure they were scheduled for.

Exclusion Criteria:

1. Upper GI or lower GI bleeding at the time of procedure
2. Large amounts of vomiting reported before the procedure (with bowel preparation)
3. Hospital inpatients
4. History of abdominal surgery
5. History of gastroparesis or other documented GI transit disorder (ex. Colonic inertia)
6. Pregnancy Patients with diabetes mellitus taking Metoclopramide without proven gastroparesis by formal testing will not be excluded.

Adult patients (ages 18 and over) scheduled for elective non-emergency outpatient combined Esophagogastroduodenoscopy and colonoscopy procedures at Cleveland Clinic Florida.