Definitions & Reference
Understand the metrics and clinical reasoning.
Key Metrics
Total urine volume passed in 24 hours, day plus night.
Percentage of the 24-hour urine output produced at night, including the first morning void.
Largest single voided volume recorded in the diary.
Average volume per void over a 24-hour cycle.
Amount left in the bladder after voiding, measured externally by ultrasound or catheter. Not derived from diary data.
Whether any leakage occurred during the diary period.
The 4Is Classification
The total amount or timing of urine output looks off. May indicate too little fluid intake, too much, or abnormal nighttime production.
The bladder may be storing too little (capacity impairment) or signaling too early (sensory impairment). Assessed by comparing MVV and AVV.
The bladder may not be emptying well. Assessed by PVR measurement. If PVR > 100 mL, voiding impairment is suspected.
Leaking is present. Determined by any reported leakage episodes or nocturnal enuresis.
Clinical Thresholds
| Metric | Low/Abnormal | Normal | High/Abnormal |
|---|---|---|---|
| 24HV | < 1,000 mL (34 oz)/day (oliguria) | 1,000–2,500 mL (34–85 oz)/day | > 2,500 mL (85 oz)/day (polyuria) |
| NPi | - | ≤ 20% (younger) / ≤ 33% (age ≥ 65) | > threshold = nocturnal polyuria |
| MVV | < 150 mL (5 oz) (small) | 150–350 mL (5–12 oz) | > 350 mL (12 oz) (large) |
| PVR | - | < 100 mL (3.4 oz) | > 100 mL (3.4 oz) (impaired emptying) |
| AVV/MVV | < 60% (sensory pattern) | 60–70% | - |
About IPC
IPC provides continuing education to health professionals to raise standards in male pelvic health treatments. To deepen your understanding of bladder diary analysis, functional diagnosis, visit ipc.health.