Maximum capacity of the urinary bladder
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Here is a concise summary of the urinary bladder's capacity:
Urinary Bladder Capacity
Normal Functional Capacity (Adults)
- 300–550 mL — the generally accepted "normal" range for adults (Wyndaele, 1999)
- First sensation of filling: ~50 mL
- First desire to void: ~150 mL
- Strong desire to void: ~250 mL
- Maximum cystometric capacity: ~400 mL (point at which voiding can no longer be delayed)
Maximum Physiological Capacity
- 600–800 mL — the elastic upper limit the bladder can accommodate before discomfort becomes severe
- >500 mL is considered abnormally large (hyposensitive/underactive bladder)
Maximum Anesthetic Capacity
- Under deep general or spinal anesthesia, the bladder can be distended beyond normal limits (used diagnostically in conditions like interstitial cystitis)
Key Definitions (ICS — International Continence Society)
| Term | Definition |
|---|---|
| Cystometric capacity | Bladder volume at end of filling cystometry, when voiding is permitted |
| Maximum cystometric capacity | Volume at which the individual can no longer delay micturition |
| Maximum anesthetic capacity | Volume achievable under general/spinal anesthesia |
Pediatric Formula (Kaefer/Hjalmas)
- Age < 2 years: capacity (oz) = (2 × age in years) + 2
- Age ≥ 2 years: capacity (oz) = (age in years ÷ 2) + 6
Clinical Notes
- Bladder capacity varies void to void and between individuals; a single urodynamic measurement may be imprecise — frequency-volume diaries over several days are more informative.
- Abnormal capacity is defined as >130% or <66% of estimated bladder capacity for age.
- In pregnancy, bladder capacity decreases due to uterine pressure (especially in the third trimester).
Sources: Smith and Tanagho's General Urology, 19th Ed., p. 505; Berek & Novak's Gynecology; Campbell-Walsh-Wein Urology
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