Changes in cardinal ligament length and curvature with parity and prolapse and their relation to level III hiatus measures

Introduction and hypothesis Test the hypotheses that (1) cardinal ligament (CL) straightening and lengthening occur with parity and prolapse, (2) CL straightening occurs before lengthening, and (3) CL length is correlated with level III measures. Methods We performed a secondary analysis of MRIs from women in three groups: (1) nulliparous with normal support, (2) parous with normal support, and (3) uterine prolapse (POP-Q point C > − 4 and Ba > 1 cm). The 3D stress MRI images at rest and maximal Valsalva were analyzed. CLs were traced from their origin to cervico-vaginal insertions. Curvature ratio was calculated as curved length/straight length. Level III measures included urogenital hiatus (UGH), levator hiatus (LH), and levator bowl volume (LBV), and their correlations with CL length were calculated. Results Ten women were included in each group. Compared to the nulliparous group, CL length was 18% longer in parous controls ( p = .04) and 59% longer with prolapse ( p < .01) at rest, while at Valsalva, CL length was 10% longer in parous controls ( p = .21) and 49% longer with prolapse ( p < .01). Curvature ratios showed 18% more straightening in women with prolapse compared to parous controls ( p < .01). Curved CL length and level III measures were moderately to strongly correlated: UGH (rest: R = 0.68, p < .01; Valsalva: R =0.80, p < .01), LH (rest: R = 0.60, p < .01; Valsalva: R = 0.78, p < .01), and LBV (rest: R = 0.71, p < .01; Valsalva: R =0.89, p < .01). Conclusion Our findings suggest that the CLs undergo three times as much lengthening with prolapse as with parity; however, straightening only occurs with prolapse. Strong correlations exist between level I and level III support.