Paper 38: Quantification of Levator Plate Angle, Levator Hiatus Length and Perineal Body Location in Women With Prolapse and Normal Controls During Valsalva Using Dynamic MRI

Abstract

OBJECTIVES: The technique of dynamic MRI allows for comparison of the levator plate angle (LPA) and other pelvic floor measures in women with prolapse and properly matched normal controls. Using this technique, we seek to answer the following questions: What is the LPA in normal controls? Is the LPA different between normal controls and prolapse cases? Does LPA relate to levator hiatus length and perineal body location? METHODS: A cohort of women with prolapse at least 1 centimeter below the hymen and controls with all points 1 centimeter or higher were enrolled in a study of pelvic organ support. Cases and controls were matched by age, race and parity. All patients underwent dynamic cine MRI in the midsagittal plane in the supine position during Valsalva. Patients were excluded from analysis if Valsalva was not properly performed or if imaging was not midsagittal. LPA was measured relative to a horizontal reference line (Figure 1). Levator hiatus length (LH) was measured from the inferior pubic point to the levator ani at the ano-rectal angle. The perineal body location (PB) was measured as the distance below the sacro-coccygeal inferior pubic point line (SCIPP). T-tests and Pearson correlation coefficients (r) were performed.FIGURE 1RESULTS: A total of 87 cases (mean age=56.8 ± 12.7) and 73 controls (55.6 ± 13.1) were analyzed. The inclinations of the LPA from the vertical axis are shown in the table. At peak Valsalva, cases had a 9o larger (more caudally directed) levator plate angle compared to controls. Cases also had a 15% larger LH length and 21% more caudal PB location compared to controls. Increases in LH length (r=0.43, P<0.0001) and PB location (r=0.52, P<0.0001) both correlated to increases in the levator plate angle.TABLE 1CONCLUSION: The measured levator plate angle in normal women (44.5o) is caudally inclined rather than previous subjective descriptions of it being “horizontal.” Women with prolapse have a modest (9o) though statistically greater levator plate angle compared to normal controls. This larger angle correlated with an increase in levator hiatus diameter and more downward perineal body location in women with prolapse compared to normal controls.