Potassium values before and after
PEG-asc for colonoscopy

Rationale: Patients undergoing colonoscopy could have an (unknown) risk of hypokalaemia due to bowel cleansing and other risk factors, such as comorbidity and age. Patients with pre-existing hypokalaemia are at risk for severe hypokalaemia. By performing this study, we want to define risk factors and provide a new protocol for bowel cleansing in our hospital.


Objective: All patients undergoing colonoscopy.


Study design: Population-based, observational study


Study population: All patients undergoing colonoscopy ≥ 18 years old.


Main study parameters/endpoints: Prevalence of hypokalaemia, mean potassium difference before/after bowel cleansing, age, gender, comorbidity, indication, and symptom related parameters.


Nature and extent of the burden and risks associated with participation, benefit and group relatedness: To minimize the risks for patients undergoing colonoscopy we will check potassium values as standard care. The existing protocol will be expanded for all patients. Every ambulatory patient visits the screening nurse for information and risk stratification. One blood sample is obtained approximately 1 week before start of bowel cleansing and one blood sample via intravenous needle (already needed for infusion of analgesics and sedation) on the day of colonoscopy.

The use of PEG-asc could contribute a significant decrease in potassium values a potentially cause serious clinical adverse events.

Analyses will be performed after colonoscopy

1. Clinical data registration

2. Evaluation of potassium measurements in patients before and after bowel preparation (standard health care)