Good urodynamic practice: Pressure signal quality immediately after catheter insertion for cystometry with a water-filled pressure transducer system and its relevance for the ICS zero procedure

AIM: This study aims to evaluate the intracorporeal pressures immediately after the insertion of the catheters for urodynamic testing with a water-filled urodynamic pressure transducer system to determine the relevance of the International Continence Society (ICS) zeroing principles.

METHODS: Here, a retrospective analysis of a random series of urodynamic recordings is performed. The initial pressures, immediately after the insertion of the catheters, have been compared with the pressures after some milliliters of filling and flushing away of the gel, used with insertion, and/or the mucus and debris from the inserted catheters. Differences of initially recorded intravesical and intrarectal pressures from those after flushing and filling are analyzed and associated with the ICS standard practice of zeroing.

RESULTS: Statistically and clinically significant differences between the initial pressures and the pressures after filling and flushing are observed, with nonphysiological initial pressures in 62% of the studies. Some filling (20 ml or more in the bladder) and flushing of the pressure channels resulted in the registration of physiological pressures and synchronous response from both lines on abdominal pressure increases.

CONCLUSIONS: The pressure signal quality of a water-filled urodynamic system immediately after catheter insertion is low with inaccurately displayed pressure values, but it changes to normal after flushing the pressure channels and some filling. Rezeroing of the intracorporeal pressures immediately after catheter insertion for cystometry is the inappropriate correction procedure that misleadingly modifies the false initial pressures, resulting in ongoing unrealistic urodynamic study pressures.