title: Biomechanical pregnant pelvic system model and numerical simulation of childbirth: impact of delivery on the uterosacral ligaments, preliminary results.
abstract: OBJECTIVE
  We created a pregnant woman pelvic model to perform a simulation of delivery to understand the pathophysiology of urogenital prolapse by studying the constraints on the pelvic components (muscles, ligaments, pelvic organs) during childbirth. These simulations will also provide valuable tools to understand and teach obstetrical mechanics.
  
  
  METHODS
  We built a numerical model of the pelvic system from a term pregnant woman, using the finite element method on a mesh built from magnetic resonance images of a nulliparous pregnant woman. Mechanical properties of pelvic tissues already determined by the team were adapted to account for pregnancy.
  
  
  RESULTS
  The system allows delivery to be simulated. When a fetal head at the 50th percentile for the term goes through the pelvic system, uterosacral ligaments undergo a deformation of around 30 %. Uterosacral ligaments are the major pelvic sustaining structures, their lesion may be a potential cause of urogenital prolapse. We built a model of childbirth as a function of pregnancy term by varying volumes of fetal head and uterus. The impact on uterosacral ligaments is higher when the fetal head is larger.
  
  
  CONCLUSIONS
  Our modelling is rather complete considering that it involves many organs including ligaments. It allows us to analyse the effect of childbirth on uterosacral ligaments and to understand how they impact on pelvic statics. First results are promising, but optimisation and future simulations will be needed. We also plan to simulate various delivery scenarios (cephalic, breech presentation, instrumental extraction), which will be useful to study perineal lesions and also to teach obstetrical mechanics.
authors.affiliation: Gynaecology Department, Jeanne de Flandre Hospital, CHRU Lille-Lille Nord University, 59000, Lille, France, lepagejulien@msn.com.
authors.forename: J
authors.initials: J
authors.lastname: Lepage
authors.forename: C
authors.initials: C
authors.lastname: Jayyosi
authors.forename: P
authors.initials: P
authors.lastname: Lecomte-Grosbras
authors.forename: M
authors.initials: M
authors.lastname: Brieu
authors.forename: C
authors.initials: C
authors.lastname: Duriez
authors.forename: M
authors.initials: M
authors.lastname: Cosson
authors.forename: C
authors.initials: C
authors.lastname: Rubod
mesh_terms: D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005260:Female; D005333:Fetus / Q000033:anatomy & histology; D020342:Finite Element Analysis; D006257:Head / Q000033:anatomy & histology*; D006801:Humans; D008022:Ligaments / Q000502:physiology*; D008954:Models, Biological; D009929:Organ Size; D056887:Pelvic Organ Prolapse / Q000209:etiology; D010388:Pelvis / Q000502:physiology*; D011247:Pregnancy / Q000502:physiology*; D047929:Term Birth / Q000502:physiology*