The first urge to void is felt at:
Cystometry refers to the process of studying the relationship between the intravesical volume and pressure, the Cystometrogram refers to a graphical record of this relationship. Normal cystometrogram shows three phases of filling: Phase Ia: It is the initial phase of filling in which pressure rises from 0 to 10 cm H2O, when about 50 mL of fluid is collected in the bladder Phase Ib: It is the phase of plateau which lasts till the bladder volume is 400 mL. The first urge to void is felt at a bladder volume of about 150 mL, and a marked sense of fullness at about 400mL. The flatness of segment Ib is a manifestation of the law of Laplace. Phase II: This phase stas beyond 400 mL volume when the pressure begins to rise markedly, triggering the micturition reflex
Bladder volume of 400 mL
Phase Ia of cystometrogram
Phase Ib of cystometrogram
Phase II of cystometrogram
Excretory System