What is a bladder diary?
April 24, 2026 · Bladder Diaries Team
A bladder diary is the starting point for almost every investigation of lower urinary tract symptoms (LUTS). It answers questions that a clinic visit can't: how much urine your patient actually produces, how that volume is split between day and night, how often they drink, and whether leaks are tied to urgency or activity.
What to record
Over three consecutive days, log:
- Voids — timestamp and volume for every trip to the toilet.
- Fluids — timestamp, type, and volume of every drink.
- Leaks — trigger (cough, laugh, urgency) and rough size (drops, small, medium, large).
- Bedtime / wake time — needed to compute nocturnal polyuria.
What it unlocks
From those three data streams, the calculator derives the standard ICS measures — 24-hour voided volume, mean voided volume, maximum voided volume, nocturnal polyuria index — and maps them onto a 4Is classification (fluid imbalance, storage impairment, voiding impairment, incontinence).
If you want the full glossary, see our definitions page.
Getting a reliable diary
Paper diaries work, but they miss data. The companion patient app at myflowcheck.com records everything live and exports a structured PDF. Upload that PDF into the calculator and the diagnosis appears in seconds.