The relationship between the perineal length measurements and the urodynamic stress incontinence

The purpose of this study was to assess the relationship between the length of perineal body, the anal position index, the total fourchette-coccyx distance and the anal-coccyx length and female urodynamic stress urinary incontinence (USUI).

The study included 57 women with USUI (group A) and 45 women without USUI as control (group B). All patients underwent a urodynamic evaluation and measurement of the length of perineal body (PB) and the distance between the fourchette and the inferior margin of coccyx (FC). PB is the distance between the fourchette and the center of anal orifice. The ratio PB/FC is the anal position index. Subtracting the PB length from FC distance equals the anal-coccyx (AC) length.

The student's t-test showed no significant statistical difference between any of the measured lengths in the two groups. Moreover, in the USUI group, ANOVA did not show any significant relationship between the urodynamic parameters and the measured lengths. Regarding to the investigated urodynamic parameters only the maximum urethral pressure (Pura max) presented a significant statistical difference between the two groups (P = 0.009).

Theoretically, a differentiation of perineal distances probably brings to the surface a laxity of the pelvic floor, a factor predisposing to USUI. Furthermore, the anterior position of anus can be a cause of constipation which also contributes to USUI. However, our study did not reveal any relationship between the perineal length measurements and USUI. Further investigation with longer series of patients is needed to show if this simple, inexpensive and non-invasive test could be added in the armamentarium of the diagnostic and prognostic investigation of USUI. Regarding to the urodynamic parameters, our results emphasize the importance of the Pura max parameter in the urodynamic evaluation of USUI.