OBJECTIVE : The maximum closure pressure (MCP) of the urethra, measured by the urethral profile, constitutes an index of urinary continence. The objective of this study, in a large population of women, was to evaluate the possible variations of MCP and functional length (FL) of the urethra, according to the position of a urodynamic probe designed to perform lateral sectorial measurements. MATERIAL AND METHODS : Measurements were performed between July and December 1998, in 230 patients with a mean age of 55 years, using a probe perfused with water and equipped with an urethral side orifice. We compared, by analysis of variance for repeated measures, MCP and mean FL at 0 o'clock (MCPm0, LFm0), 3 o'clock (MCPm3, LFm3), 6 o'clock (MCPm6, LFm6) and 9 o'clock (MCPm9, LFm9). RESULTS : The values for MCPm and LFm obtained according to the rotation of the probe were as follows : MCPm0 = 65.68 ± 12.46 cmH20, , MPCm3 = 55.44 ± 16.97 cmH20, MCPm6 = 58.07 ± 15.85 cmH20, and MCPm9 = 53.85 ± 16.89 cmH20, LFm0 = 28.92 ± 5.32 mm, LFm3 = 30.18 ± 6.82 mm, LFm6 = 32.40 ± 6.82 mm and LFm9 = 30.83 ± 6.07 mm.
CONCLUSION : LCP may variable considerably in the same subject according to rotation of the probe. In our series, MCPm at 0 o'clock was significantly higher than MCPm at 3 o'clock, 6 o'clock and 9 o'clock. This difference appears to increase with age. The lowest values for MCPm were observed at 3 o'clock and 9 o'clock. The MCPm at 6 o'clock was intermediate and the closest value to the mean pressure calculated from MCPm in the four positions. On the other hand, FL varied only slightly according to the position of the probe.