CYSTOMETER

Typical Number in Hospital: 3

Cost Bands: 4

References:

A cystometer measures the pressure in the bladder as it fills. Although this could theoretically be performed during natural filling, it is normally performed by infusing water or saline through a urethral catheter. Cystometry is an important diagnostic test in the investigation of urinary incontinence or retention.

Cystometers can be purchased as independent instruments comprising a strip chart recorder, a pressure measuring device connected to the chart recorder, and an infusion pump or infusion controller to deliver the fluid. The result is a graph of pressure against volume known as a cystometrogram. The normal result shows little or no rise in pressure during filling (0-15 cmH2O pressure up to 500 ml in adults) whereas some abnormal results show involuntary contractions of the bladder.

Modern cystometers are electronic and usually infuse water or saline but other types do exist which are mechanical, using aneroid pressure measuring devices and/or infusing carbon dioxide rather than a liquid. Cystometry is more commonly performed using a polygraph on which other tests and recordings are made. Additional recordings may include rectal pressure, urethral pressure and flow, flow velocity during voiding, and electromyography of the urethral sphincter or adjacent muscles.

Such apparatus would be used by urologists or gynaecologists in the X-ray suite or in a special 'urodynamics' clinic.