Surgical and Radiologic Anatomy

, Volume 40, Issue 4, pp 371–380 | Cite as

Comparative anatomy on 3-D MRI of the urogenital sinus and the periurethral area before and during the second stage of labor during childbirth

  • Jean-Christophe Maran
  • Lucie Cassagnes
  • Vincent Delmas
  • Dominique Musset
  • René Frydman
  • Gérard Mage
  • Michel Canis
  • Louis Boyer
  • Olivier Ami
Original Article


Purpose of the study

To describe the observable MRI changes in the urogenital sinus during the second stage of labor and delivery by comparing the changes in the positions of the anatomical structures of the maternal perineum using MRI-based vector 3-D models.

Materials and methods

Seven pregnant women underwent 3-D MRI sequences using a Philips 1 T Panorama open MRI during the pre-labor period and during the second stage of labor. A 3-D vector reconstruction platform (BABYPROGRESS, France) enabled the transformation of volumes of 2-D images into finite element meshes. The polygonal meshes labeled with the principal components of the urogenital sinus were used as part of a biomechanical study of the pressure exerted on the perineum during fetal descent.


The expansion of the urogenital sinus was observed in all patients. Qualitative stretching was observed toward the rear and bottom of the iliococcygeus, pubococcygeus, puborectalis and obturator internus muscles. Significant length differences were measured along the iliococcygeus and pubococcygeus muscles but not along the tendinous arch of the levator ani or the puborectalis muscle. The inversion of the levator ani muscle curvature was accompanied by the transmission of pressure generated during fetal descent to the pubic muscle insertions and the descent of the tendinous arch of the levator ani.


Mechanical pressures responsible for the tensioning of the constituent muscles of the urogenital sinus were qualitatively identified during the second stage of labor. MRI-based vector 3-D models allow the quantitative assessment of levator ani muscle stretching during labor, but 2-D MRI is not sufficient for describing perineal expansion. Vector 3-D models from larger scale studies have the potential to aid in the calibration of a realistic simulation based on the consideration of the reaction of each muscular element. These models offer perspectives to enhance our knowledge regarding perineal expansion during childbirth as a risk factor for postpartum perineal defects.


Birth imaging Magnetic resonance imaging (MRI) Anatomy Urogenital sinus Female perineum 



Magnetic resonance imaging


Urogenital sinus


Tendinous arch of levator ani


Iliococcygeus muscle


Pubococcygeus muscle


Puborectalis muscle


Institutional review board


French National Agency for Drug and Medical Product Safety


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflicts of interest to disclose.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


  1. 1.
    Ami O, Chabrot P, Jardon K, Rocas D, Delmas V, Boyer L, Mage G (2011) Detection of cephalopelvic disproportion using a virtual reality model: a feasibility study of three cases. J Radiol 92:40–45. doi: 10.1016/j.jradio.2009.05.001 CrossRefPubMedGoogle Scholar
  2. 2.
    Ami O, Chabrot P, Rabischong B, Rocas D, Delmas V, Boyer L, Mage G (2010) Tridimensional vector animation from fetal MRI as a simulation of delivery. J Radiol 91:515–517CrossRefPubMedGoogle Scholar
  3. 3.
    Arenholt LTS, Pedersen BG, Glavind K, Glavind-Kristensen M, DeLancey JOL (2016) Paravaginal defect: anatomy, clinical findings, and imaging. Int Urogynecol J. doi: 10.1007/s00192-016-3096-3 PubMedGoogle Scholar
  4. 4.
    Bamberg C, Deprest J, Sindhwani N, Teichgräberg U, Güttler F, Dudenhausen JW, Kalache KD, Henrich W (2016) Evaluating fetal head dimension changes during labor using open magnetic resonance imaging. J Perinat Med. doi: 10.1515/jpm-2016-0005 Google Scholar
  5. 5.
    Bamberg C, Rademacher G, Güttler F, Teichgräber U, Cremer M, Bührer C, Spies C, Hinkson L, Henrich W, Kalache KD, Dudenhausen JW (2012) Human birth observed in real-time open magnetic resonance imaging. Am J Obstet Gynecol 206:505.e1–505.e6. doi:  10.1016/j.ajog.2012.01.011 CrossRefGoogle Scholar
  6. 6.
    Buttin R, Zara F, Shariat B, Redarce T, Grangé G (2013) Biomechanical simulation of the fetal descent without imposed theoretical trajectory. Comput Methods Programs Biomed 111:389–401. doi: 10.1016/j.cmpb.2013.04.005 CrossRefPubMedGoogle Scholar
  7. 7.
    Cosson M, Rubod C, Vallet A, Witz J-F, Brieu M (2011) Biomechanical modeling of pelvic organ mobility: towards personalized medicine. Bull Acad Natl Méd 195:1869–1883 (discussion 1883) PubMedGoogle Scholar
  8. 8.
    Delmas V, Ami O, Iba-Zizen M-T (2010) Dynamic study of the female levator ani muscle using MRI 3D vectorial modeling. Bull Acad Natl Méd 194:969–980 (discussion 981–982) PubMedGoogle Scholar
  9. 9.
    Dietz HP, Lanzarone V (2005) Measuring engagement of the fetal head: validity and reproducibility of a new ultrasound technique. Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol 25:165–168. doi: 10.1002/uog.1765 CrossRefGoogle Scholar
  10. 10.
    Dietz HP, Shek KL (2009) Levator defects can be detected by 2D translabial ultrasound. Int Urogynecol J Pelvic Floor Dysfunct 20:807–811. doi: 10.1007/s00192-009-0839-4 CrossRefPubMedGoogle Scholar
  11. 11.
    Eisenberg VH, Chantarasorn V, Shek KL, Dietz HP (2010) Does levator ani injury affect cystocele type? Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol 36:618–623. doi: 10.1002/uog.7712 CrossRefGoogle Scholar
  12. 12.
    Güttler FV, Heinrich A, Rump J, de Bucourt M, Schnackenburg B, Bamberg C, Hamm B, Teichgräber UK (2012) Magnetic resonance imaging of the active second stage of labour: proof of principle. Eur Radiol 22:2020–2026. doi: 10.1007/s00330-012-2455-9 CrossRefPubMedGoogle Scholar
  13. 13.
    Howard D, Makhlouf M (2016) Can pelvic floor dysfunction after vaginal birth be prevented? Int Urogynecol J. doi: 10.1007/s00192-016-3117-2 PubMedGoogle Scholar
  14. 14.
    Hoyte L, Brubaker L, Fielding JR, Lockhart ME, Heilbrun ME, Salomon CG, Ye W, Brown MB, Pelvic Floor Disorders Network (2009) Measurements from image-based three dimensional pelvic floor reconstruction: a study of inter- and intraobserver reliability. J Magn Reson Imaging JMRI 30:344–350. doi: 10.1002/jmri.21847 CrossRefPubMedGoogle Scholar
  15. 15.
    Hoyte L, Damaser MS (2007) Magnetic resonance-based female pelvic anatomy as relevant for maternal childbirth injury simulations. Ann N Y Acad Sci 1101:361–376. doi: 10.1196/annals.1389.018 CrossRefPubMedGoogle Scholar
  16. 16.
    Hoyte L, Ye W, Brubaker L, Fielding JR, Lockhart ME, Heilbrun ME, Brown MB, Warfield SK, Pelvic Floor Disorders Network (2011) Segmentations of MRI images of the female pelvic floor: a study of inter- and intra-reader reliability. J Magn Reson Imaging JMRI 33:684–691. doi: 10.1002/jmri.22478 CrossRefPubMedGoogle Scholar
  17. 17.
    Lamblin G, Mayeur O, Giraudet G, Jean Dit Gautier E, Chene G, Brieu M, Rubod C, Cosson M (2016) Pathophysiological aspects of cystocele with a 3D finite elements model. Arch Gynecol Obstet. doi: 10.1007/s00404-016-4150-6 Google Scholar
  18. 18.
    Lapeer R, Audinis V, Gerikhanov Z, Dupuis O (2014) A computer-based simulation of obstetric forceps placement. Med Image Comput Comput-Assist Interv MICCAI Int Conf Med Image Comput Comput-Assist Interv 17:57–64Google Scholar
  19. 19.
    Lee S-L, Tan E, Khullar V, Gedroyc W, Darzi A, Yang G-Z (2009) Physical-based statistical shape modeling of the levator ani. IEEE Trans Med Imaging 28:926–936. doi: 10.1109/TMI.2009.2012894 CrossRefPubMedGoogle Scholar
  20. 20.
    Lepage J, Cosson M, Mayeur O, Brieu M, Rubod C (2016) The role of childbirth research simulators in clinical practice. Int J Gynaecol Obstet Off Organ Int Fed Gynaecol Obstet 132:234–235. doi: 10.1016/j.ijgo.2015.07.017 CrossRefGoogle Scholar
  21. 21.
    Lepage J, Jayyosi C, Lecomte-Grosbras P, Brieu M, Duriez C, Cosson M, Rubod C (2015) Biomechanical pregnant pelvic system model and numerical simulation of childbirth: impact of delivery on the uterosacral ligaments, preliminary results. Int Urogynecol J 26:497–504. doi: 10.1007/s00192-014-2498-3 CrossRefPubMedGoogle Scholar
  22. 22.
    da Leroy L, Lúcio A, de Lopes MHBM (2016) Risk factors for postpartum urinary incontinence. Rev Esc Enferm UP 50:200–207. doi: 10.1590/S0080-623420160000200004 CrossRefGoogle Scholar
  23. 23.
    Lien K-C, Morgan DM, Delancey JOL, Ashton-Miller JA (2005) Pudendal nerve stretch during vaginal birth: a 3D computer simulation. Am J Obstet Gynecol 192:1669–1676. doi: 10.1016/j.ajog.2005.01.032 CrossRefPubMedGoogle Scholar
  24. 24.
    Li X, Kruger JA, Nash MP, Nielsen PMF (2010) Effects of nonlinear muscle elasticity on pelvic floor mechanics during vaginal childbirth. J Biomech Eng 132:111010. doi: 10.1115/1.4002558 CrossRefPubMedGoogle Scholar
  25. 25.
    Miller JM, Low LK, Zielinski R, Smith AR, DeLancey JOL, Brandon C (2015) Evaluating maternal recovery from labor and delivery: bone and levator ani injuries. Am J Obstet Gynecol 213:188.e1–188.e11. doi: 10.1016/j.ajog.2015.05.001 CrossRefGoogle Scholar
  26. 26.
    Oliveira DA, Parente MPL, Calvo B, Mascarenhas T, Natal Jorge RM (2016) Numerical simulation of the damage evolution in the pelvic floor muscles during childbirth. J Biomech 49:594–601. doi: 10.1016/j.jbiomech.2016.01.014 CrossRefPubMedGoogle Scholar
  27. 27.
    Shi M, Shang S, Xie B, Wang J, Hu B, Sun X, Wu J, Hong N (2016) MRI changes of pelvic floor and pubic bone observed in primiparous women after childbirth by normal vaginal delivery. Arch Gynecol Obstet 294:285–289. doi: 10.1007/s00404-016-4023-z CrossRefPubMedPubMedCentralGoogle Scholar
  28. 28.
    Silva MET, Oliveira DA, Roza TH, Brandão S, Parente MPL, Mascarenhas T, Natal Jorge RM (2015) Study on the influence of the fetus head molding on the biomechanical behavior of the pelvic floor muscles, during vaginal delivery. J Biomech 48:1600–1605. doi: 10.1016/j.jbiomech.2015.02.032 CrossRefPubMedGoogle Scholar
  29. 29.
    Tracy PV, DeLancey JO, Ashton-Miller JA (2016) A geometric capacity-demand analysis of maternal levator muscle stretch required for vaginal delivery. J Biomech Eng 138:021001. doi: 10.1115/1.4032424 CrossRefPubMedGoogle Scholar
  30. 30.
    Unger CA, Weinstein MM, Pretorius DH (2011) Pelvic floor imaging. Obstet Gynecol Clin North Am 38:23–43. doi: 10.1016/j.ogc.2011.02.002 CrossRefPubMedGoogle Scholar
  31. 31.
    van Veelen A, Schweitzer K, van der Vaart H (2014) Ultrasound assessment of urethral support in women with stress urinary incontinence during and after first pregnancy. Obstet Gynecol 124:249–256. doi: 10.1097/AOG.0000000000000355 CrossRefPubMedGoogle Scholar
  32. 32.
    Vergeldt TFM, Notten KJB, Stoker J, Fütterer JJ, Beets-Tan RG, Vliegen RFA, Schweitzer KJ, Mulder FEM, van Kuijk SMJ, Roovers JPWR, Kluivers KB, Weemhoff M (2016) Comparison of translabial three-dimensional ultrasound with magnetic resonance imaging for measurement of levator hiatal biometry at rest. Ultrasound Obstet Gynecol Off J Int Soc Ultrasound Obstet Gynecol 47:636–641. doi: 10.1002/uog.14949 CrossRefGoogle Scholar
  33. 33.
    Wijma J, Weis Potters AE, van der Mark TW, Tinga DJ, Aarnoudse JG (2007) Displacement and recovery of the vesical neck position during pregnancy and after childbirth. Neurourol Urodyn 26:372–376. doi: 10.1002/nau.20354 CrossRefPubMedGoogle Scholar
  34. 34.
    Zacharin RF (1968) The anatomic supports of the female urethra. Obstet Gynecol 32:754–759PubMedGoogle Scholar
  35. 35.
    Zacharin RF (1977) Abdominoperineal urethral suspension: a 10-year experience in the management of recurrent stress incontinence of urine. Obstet Gynecol 50:1–8PubMedGoogle Scholar

Copyright information

© Springer-Verlag France SAS 2017

Authors and Affiliations

  • Jean-Christophe Maran
    • 1
    • 2
    • 3
  • Lucie Cassagnes
    • 3
    • 4
  • Vincent Delmas
    • 2
  • Dominique Musset
    • 5
  • René Frydman
    • 6
  • Gérard Mage
    • 7
  • Michel Canis
    • 7
  • Louis Boyer
    • 3
    • 4
  • Olivier Ami
    • 1
    • 3
    • 8
    • 9
  1. 1.Plateforme de recherche IMAGINAITREParisFrance
  2. 2.Unité de Recherche en Développement, Imagerie et Anatomie (URDIA)Université Paris DescartesParisFrance
  3. 3.Institut Pascal, Image Guided Therapies (IGT)AubièreFrance
  4. 4.CHU de Clermont Ferrand 1-Pôle de RadiologieClermont FerrandFrance
  5. 5.Université Paris Sud 11OrsayFrance
  6. 6.Université Paris DescartesParisFrance
  7. 7.Service de gynécologie-obstétriqueCHU de Clermont Ferrand 1Clermont FerrandFrance
  8. 8.Service de gynécologie-obstétriqueClinique de l’EssonneEvryFrance
  9. 9.Clinique de la MuetteRamsay Générale de SantéParisFrance

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