Colonoscopy Prep Calculator

This calculator covers two separate jobs that colonoscopy prep involves: planning the split-dose regimen before the procedure, and scoring how well that prep actually worked afterward. The volume side is driven entirely by which prep solution is selected -- standard 4-liter PEG-ELS (GoLYTELY-style), low-volume 2-liter PEG with ascorbic acid (MoviPrep-style), or the roughly 946 mL of DILUTED drinking solution used with sodium sulfate (Suprep-style: two 177 mL concentrate bottles, each mixed with water to a 473 mL/16 oz dose -- 946 mL is the diluted total, not the raw concentrate volume) -- split evenly into an evening-before dose and a morning-of dose, calculated to FINISH 4 to 5 hours before the scheduled procedure time, per split-dose being the current standard of care for prep quality and adenoma detection. The morning dose's start time is back-calculated from that finish target and how long the dose itself takes to drink, floored at 3 AM so patients aren't asked to start before then; that floor only binds for early-morning procedures (roughly procedureHour 8 AM or earlier) -- for an afternoon procedure the calculated start time is already well after 3 AM. Body weight is captured because some protocols scale standard PEG-ELS volume at the extremes of body size, but at moderate weights it has no effect on the calculated volume, and this tool does not weight-adjust the low-volume or sodium-sulfate options at all; the below-50kg PEG-ELS reduction to 3 liters is this calculator's own practical adjustment for smaller patients, not a dose specified in product labelling.

The scoring side implements the Boston Bowel Preparation Scale, which grades the right colon, transverse colon, and left colon separately from 0 (unprepared) to 3 (entire mucosa seen) and sums them to a 0-9 total; a prep is considered adequate only when the total is 6 or higher AND every individual segment scores at least 2, since a single poorly seen segment can hide a lesion even when the overall total looks acceptable. This tool does not adjust dosing for renal impairment, prior poor preps, or specific bowel motility issues, and any deviation from a standard protocol should follow institutional or endoscopist-specific guidance. The BBPS itself was introduced and validated by Lai and colleagues at Boston University Medical Center in a 2009 study, and it has since become the most widely used bowel-prep grading instrument in colonoscopy research.