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Quantity and distribution of levator ani stretch during simulated vaginal childbirth

      Objective

      The objective of the study was to develop a model of the female pelvic floor to study levator stretch during simulated childbirth.

      Study Design

      Magnetic resonance data from an asymptomatic nulligravida were segmented into pelvic muscles and bones to create a simulation model. Stiffness estimates of lateral and anteroposterior levator attachments were varied to estimate the impact on levator stretch. A 9 cm sphere was passed through the pelvis, along the path of the vagina, simulating childbirth. Levator response was interpreted at 4 positions of the sphere, simulating fetal head descent. The levator was color mapped to display the stretch experienced.

      Results

      A maximum stretch ratio of 3.5 to 1 was seen in the posteriomedial puborectalis. Maximum stretch increased with increasing stiffness of lateral levator attachments.

      Conclusion

      Although preliminary, this work may help explain epidemiologic data regarding the pelvic floor impact of a first delivery. The models and simulation technique need refinement, but they may help study the effect of labor parameters on the pelvic floor.

      Key words

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      References

        • Thom D.
        Variation in estimates of urinary incontinence prevalence in the community: Effects of differences in definition, population characteristics, and study type.
        J Am Geriatr Soc. 1998; 46: 473-480
        • Wilson L.
        • Brown J.S.
        • Shin G.P.
        • Luc K.O.
        • Subak L.L.
        Annual direct cost of urinary incontinence.
        Obstet Gynecol. 2001; 98: 398-406
        • Samuelsson E.C.
        • Arne-Victor F.T.
        • Tibbin G.
        • Svardsudd K.F.
        Signs of genital prolapse in a Swedish population of women 20 to 59 years of age and possible related factors.
        Am J Obstet Gynecol. 1999; 180: 299-305
        • Wilcox L.S.
        • Koonin L.M.
        • Pokras R.
        • Strauss L.T.
        • Xia Z.
        • Peterson H.B.
        Hysterectomy in the United States, 1988-1990.
        Obstet Gynecol. 1994; 83: 549-555
        • Subak L.L.
        • Waetjen L.E.
        • van den Eeden S.
        • Thom D.H.
        • Vittinghoff E.
        • Brown J.S.
        Cost of pelvic organ prolapse surgery in the United States.
        Obstet Gynecol. 2001; 98: 646-651
        • Rortveit G.
        • Daltveit A.K.
        • Hannestad Y.S.
        • Hunskaar S.
        Urinary incontinence after vaginal delivery or cesarean section.
        N Engl J Med. 2003; 348: 900-907
        • Snooks S.J.
        • Swash M.
        • Mathers S.E.
        • Henry M.M.
        Effect of vaginal delivery on the pelvic floor: A 5-year follow-up.
        Br J Surg. 1990; 77: 1358-1360
        • DeLancey J.O.
        • Kearney R.
        • Chou Q.
        • Speights S.
        • Binno S.
        The appearance of levator ani muscle abnormalities in magnetic resonance images after vaginal delivery.
        Obstet Gynecol. 2003; 101: 46-53
        • Sze E.H.M.
        • Kohli N.
        • Miklos J.R.
        • Roat T.
        • Karram M.M.
        Computed tomography comparison of bony pelvis dimensions between women with and without genital prolapse.
        Obstet Gynecol. 1999; 93: 229-232
        • Handa V.L.
        • Pannu H.K.
        • Siddique S.
        • Gutman R.
        • VanRooyen J.
        • Cundiff G.
        Architectural differences in the bony pelvis of women with and without pelvic floor disorders.
        Obstet Gynecol. 2003; 102: 1283-1290
        • Lien K.-C.
        • Mooney B.
        • DeLancey J.O.L.
        • Ashton-Miller J.A.
        Levator ani muscle stretch induced by simulated vaginal birth.
        Obstet Gynecol. 2004; 103: 31-40
        • Gering D.T.
        • Nabavi A.
        • Kikinis R.
        • et al.
        An integrated visualization system for surgical planning and guidance using image fusion and an open MR.
        J Magn Reson Imaging. 2001; 13: 967-975
        • Hoyte L.
        • Schierlitz L.
        • Zou K.
        • Flesh G.
        • Fielding J.R.
        Two and 3 dimensional MRI comparison of levator ani structure, volume and integrity in women with stress incontinence and prolapse.
        Am J Obstet Gynecol. 2001; 185: 11-19
        • Popinet S.
        GNU Triangulated Surface Library.
        (2004) (Accessed July 13, 2004)
        • Krysl P.
        • Ortiz M.
        Extraction of boundary representation from surface triangulations.
        Int J Numer Methods Eng. 2001; 50: 1737-1758
        • Krysl P.
        • Ortiz M.
        Delaunay approach to the generation of tetrahedral finite element meshes.
        Int J Numer Methods Eng. 2001; 50: 1681-1700
        • Belytschko T.
        • Krysl P.
        • Krongauz Y.
        A three-dimensional explicit element-free Galerkin method.
        Int J Numer Methods Fluids. 1997; 24: 1253-1270
        • Blemker S.S.
        • Pinsky P.M.
        • Delp S.L.
        A 3-D model of muscle reveals the causes of nonuniform strains in the biceps brachii.
        J Biomech. 2005; 38: 657-665