Pressure/flow cystometry

Bladder contracture is best assessed with video urodynamics. Often during the filling phase there is a reduction in the volumes at which bladder sensations such as the first sensation of filling occur and the maximum cystometric capacity (MCC) is also reduced, giving the urodynamic appearance of bladder hyper-sensitivity. The compliance of the bladder is also often severely reduced, due to fibrosis of the detrusor muscle (Chapter 4). The findings must be interpreted in the context of data from a bladder diary and an assessment of anatomical bladder capacity.

In some instances there may be fibrosis around the bladder neck, thereby preventing adequate closure during filling and leading to incontinence. The incontinence may be due to the pressure rise in the bladder secondary to poor compliance or may be due to increased transmission of intra-abdominal pressure (stress incontinence). In patients considering an entero-cystoplasty, the outlet should be urodynamically assessed for the presence of intrinsic sphincter deficiency and the subsequent need for surgical correction at the time of bladder augmentation. Frequently there is fibrosis around the ureteric orifices, preventing closure with resultant vesicoureteric reflux. In severe cases the upper tracts may act as a ‘reservoir’ for urine (with gross hydronephrosis) and may hold far more urine than the bladder.

Voiding may also be affected; fibrosis of the detrusor will lead to inefficient contractions and detrusor underactivity (Chapter 6). The result will be a weak detrusor contraction coupled with a poor flow rate, prolonged voiding and raised PVR; often the patient uses abdominal straining to aid voiding (low pressure, low flow voiding).

Video screening will not only determine if incontinence or vesicoureteric reflux is present but usually shows that the bladder is small and unusually spherical in appearance (Figure 8.1).

Figure 8.1 Typical urodynamic appearances for a contracted bladder, summarizing the varied features that may be present on video urodynamics.