A prospective randomised controlled study was performed in order to study the effectiveness of a device designed to reduce the variability in intra-abdominal pressures generated by individuals performing the Valsalva manoeuvre. One hundred women were recruited to take part in the project which compared a traditional Valsalva manoeuvre following standardised verbal instruction with forced expiration through a flow restriction device called a "valsalvometer". The abdominal pressure was measured using an air-filled rectal balloon catheter linked to a pressure transducer. The use of the valsalvometer was associated with a reduction in variation of intra-abdominal pressure between women to 50% of the standard deviation. The new device has the capacity to reduce the variation in intra-abdominal pressure produced when performing the Valsalva manoeuvre. The rise in intra-abdominal pressure may act as a standard against which other measurements are made.