Measurement of the pubic portion of the levator ani muscle in women with unilateral defects in 3â D models from MR images

ObjectiveDevelop a method to quantify the crossâ sectional area of the pubic portion of the levator ani muscle, validate the method in women with unilateral muscle defects, and report preliminary findings in those women.MethodMultiâ planar proton density magnetic resonance images of 12 women with a unilateral defect in the pubic portion of their levator ani were selected from a larger study of levator ani muscle anatomy in women with and without genital prolapse. Threeâ dimensional bilateral models of the levator ani were reconstructed (using 3â D Slicer, version 2.1b1) and divided into iliococcygeal and pubic portions. Muscle crossâ sectional areas were calculated at four equally spaced locations perpendicular to a line drawn from the pubic origin to the visceral insertion using the Iâ DEAS® computer modeling software.ResultsThe crossâ sectional area of the muscle on the side with the defect was smaller than the normal side at all the four locations. The average bilateral difference was up to 81% at location 1 (nearest pubic origin). Almost all of the volume difference (13.7%, P = 0.0004) was attributable to a reduction in the pubic portion (24.6%, P < 0.0001), not the iliococcygeal portion (P = 0.64), of the muscle.ConclusionsA method was developed to quantify crossâ sectional area of the pubic portion of the levator ani perpendicular to the intact muscle direction. Significant bilateral crossâ sectional area differences were found between intact and defective muscles in women with a unilateral defect.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135155/1/ijgo234.pd

Functional Anatomy of the Female Pelvic Floor

The anatomic structures in the female that prevent incontinence and genital organ prolapse on increases in abdominal pressure during daily activities include sphincteric and supportive systems. In the urethra, the action of the vesical neck and urethral sphincteric mechanisms maintains urethral closure pressure above bladder pressure. Decreases in the number of striated muscle fibers of the sphincter occur with age and parity. A supportive hammock under the urethra and vesical neck provides a firm backstop against which the urethra is compressed during increases in abdominal pressure to maintain urethral closure pressures above the rapidly increasing bladder pressure. This supporting layer consists of the anterior vaginal wall and the connective tissue that attaches it to the pelvic bones through the pubovaginal portion of the levator ani muscle, and the uterosacral and cardinal ligaments comprising the tendinous arch of the pelvic fascia. At rest the levator ani maintains closure of the urogenital hiatus. They are additionally recruited to maintain hiatal closure in the face of inertial loads related to visceral accelerations as well as abdominal pressurization in daily activities involving recruitment of the abdominal wall musculature and diaphragm. Vaginal birth is associated with an increased risk of levator ani defects, as well as genital organ prolapse and urinary incontinence. Computer models indicate that vaginal birth places the levator ani under tissue stretch ratios of up to 3.3 and the pudendal nerve under strains of up to 33%, respectively. Research is needed to better identify the pathomechanics of these conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72597/1/annals.1389.034.pd

FE Simulation for the Understanding of the Median Cystocele Prolapse Occurrence

International audienceFemale pelvic organ prolapse is a complex mechanism combining the mechanical behavior of the tissues involved and their geometry defects. The developed approach consists in generating a parametric FE model of the whole pelvic system to analyze the influence of this material and geometric combination on median cystocele prolapse occurrence. In accordance with epidemiological and anatomical literature, the results of the numerical approach proposed show that the geometrical aspects have a stronger influence than material properties. The fascia between the bladder and vagina and paravaginal ligaments are the most important anatomical structures inducing the amplitude of cystocele prolapse. This FE model has also allowed studying the coupled effect, showing a significant influence of the fascia size. The study allows highlighting the origins of the median cystocele prolapse and responds to this major issue of mobility occurrence

Anatomical and functional changes in the lower urinary tract during pregnancy

Objective To assess the prevalence and the development of urinary incontinence in nulliparous pregnant women, both subjectively and objectively, and to investigate the relation of incontinence with the mobility of the urethro-vesical junction measured by perineal ultrasound. Design A prospective longitudinal study. Setting University Hospital and Martini Hospital Groningen, the Netherlands. Population A cohort of 117 nulliparous pregnant women and 27 nulliparous non-pregnant controls. Methods Urinary incontinence was measured by a questionnaire and by a 24-hour pad test. The position of the urethro-vesical junction and its mobility were measured by perineal ultrasound. Main outcome measure Prevalence of urinary incontinence; mobility of the urethro-vesical junction, indicated by the displacement/pressure coefficient. Results Up to 35% of the women reported urinary incontinence in pregnancy, and 20% of the women had a positive pad test. The angle of the urethro-vesical junction angle at rest and the displacement/pressure coefficient during coughing showed a significant increasing trend during pregnancy, but no changes were seen during the Valsalva manoeuvre. No relationship was found between subjective and objective incontinence data and the position and mobility of the urethro-vesical junction. Conclusion The prevalence of incontinence in nulliparous women as found by the pad test was significantly higher in pregnancy (20%) than in the non-pregnant control group (4%). Perineal ultrasound of the urethrovesical junction showed lowering of the pelvic floor occurring as early as 12-16 weeks of pregnancy. Serial measurements of the displacement/pressure coefficient suggest that the dynamic characteristics of the connective tissues of the pelvic floor remain unaltered,whereas a significant decrease in pelvic floor muscle contraction occurs. Since no relation was found between measurements of the urethro-vesical junction and incontinence, urinary incontinence in pregnancy is most likely explained by other factors