Bladder stretch during increase in abdominal pressure.

The circumference of single bladder projections (CBP) was estimated from oblique and lateral cystographs obtained in the supine and erect positions during both rest and straining, with and without electric stimulation of the pelvic floor. The results obtained indicate an increase of CBP and a flattening of the bladder during an increase of abdominal pressure, and a decrease of CBP during electrical stimulation. Increase of CBP means an increase in the stretching of the bladder wall, which may produce an increase in the forces in the bladder wall and hence act to open the bladder neck. The decrease of the CBP during electrical stimulation of the pelvic floor indicates that the pelvic floor support reduces flattening of the bladder and hence limits the development of the bladder wall stretch.