0
Research Papers

A Parameterized Ultrasound-Based Finite Element Analysis of the Mechanical Environment of Pregnancy

[+] Author and Article Information
Andrea R. Westervelt

Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
e-mail: arw2181@columbia.edu

Michael Fernandez

Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
e-mail: mjf2152@columbia.edu

Michael House

Department of Obstetrics and Gynecology,
Tufts Medical Center,
Boston, MA 02111
e-mail: mhouse@tuftsmedicalcenter.org

Joy Vink

Department of Obstetrics and Gynecology,
Columbia University Medical Center,
New York, NY 10032
e-mail: jyv2101@cumc.columbia.edu

Chia-Ling Nhan-Chang

Department of Obstetrics and Gynecology,
Columbia University Medical Center,
New York, NY 10032
e-mail: cn2281@cumc.columbia.edu

Ronald Wapner

Department of Obstetrics and Gynecology,
Columbia University Medical Center,
New York, NY 10032
e-mail: rw2181@cumc.columbia.edu

Kristin M. Myers

Mem. ASME
Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
e-mail: kmm2233@columbia.edu

1Corresponding author.

Manuscript received July 15, 2016; final manuscript received March 3, 2017; published online April 5, 2017. Assoc. Editor: Steven D. Abramowitch.

J Biomech Eng 139(5), 051004 (Apr 05, 2017) (11 pages) Paper No: BIO-16-1296; doi: 10.1115/1.4036259 History: Received July 15, 2016; Revised March 03, 2017

Preterm birth is the leading cause of childhood mortality and can lead to health risks in survivors. The mechanical functions of the uterus, fetal membranes, and cervix have dynamic roles to protect the fetus during gestation. To understand their mechanical function and relation to preterm birth, we built a three-dimensional parameterized finite element model of pregnancy. This model is generated by an automated procedure that is informed by maternal ultrasound measurements. A baseline model at 25 weeks of gestation was characterized, and to visualize the impact of cervical structural parameters on tissue stretch, we evaluated the model sensitivity to (1) anterior uterocervical angle, (2) cervical length, (3) posterior cervical offset, and (4) cervical stiffness. We found that cervical tissue stretching is minimal when the cervical canal is aligned with the longitudinal uterine axis, and a softer cervix is more sensitive to changes in the geometric variables tested.

FIGURES IN THIS ARTICLE
<>
Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Wray, S. , Burdyga, T. , Noble, D. , Noble, K. , Borysova, L. , and Arrowsmith, S. , 2015, “ Progress in Understanding Electro-Mechanical Signalling in the Myometrium,” Acta Physiol., 213(2), pp. 417–431. [CrossRef]
Adams Waldorf, K. M. , Singh, N. , Mohan, A. R. , Young, R. C. , Ngo, L. , Das, A. , Tsai, J. , Bansal, A. , Paolella, L. , Herbert, B. R. , Sooranna, S. R. , Gough, G. M. , Astley, C. , Vogel, K. , Baldessari, A. E. , Bammler, T. K. , MacDonald, J. , Gravett, M. G. , Rajagopal, L. , and Johnson, M. R. , 2015, “ Uterine Overdistention Induces Preterm Labor Mediated by Inflammation: Observations in Pregnant Women and Nonhuman Primates,” Am. J. Obstet. Gynecol., 213(6), pp. 830.e1–830.e19. [CrossRef] [PubMed]
Blencowe, H. , Cousens, S. , Chou, D. , Oestergaard, M. , Say, L. , Moller, A. , Kinney, M. , and Lawn, J. , and Born Too Soon Preterm Birth Action Group, 2013, “ Born Too Soon: The Global Epidemiology of 15 Million Preterm Births,” Reprod. Health, 10(Suppl. 1), p. S2. [CrossRef] [PubMed]
WHO, 2014, “ World Health Organization Fact Sheet No. 363, Updated Nov. 17th, 2014,” World Health Organization, Geneva, Switzerland, Last accessed on Mar. 12, 2014, http://www.who.int/mediacentre/factsheets/fs363/en/#
Mathews, T. , and MacDorman, M. F. , 2013, “ Infant Mortality Statistics From the 2009 Period Linked Birth/Infant Death Data Set,” Natl. Vital Stat. Rep., 62(8), pp. 1–26.
Callaghan, W. , MacDorman, M. , Rasmussen, S. , Qin, C. , and Lackritz, E. , 2006, “ The Contribution of Preterm Birth to Infant Mortality Rates in the United States,” Pediatrics, 118(4), pp. 1566–1573. [CrossRef] [PubMed]
Vink, J. , and Feltovich, H. , 2016, “ Cervical Etiology of Spontaneous Preterm Birth,” Semin. Fetal Neonat. Med., 21(2), pp. 106–112. [CrossRef]
Iams, J. D. , 2014, “ Prevention of Preterm Parturition,” N. Engl. J. Med., 370(3), pp. 254–261. [CrossRef] [PubMed]
Barros, F. C. , Papageorghiou, A. T. , Victora, C. G. , Noble, J. A. , Pang, R. , Iams, J. , Cheikh Ismail, L. , Goldenberg, R. L. , Lambert, A. , Kramer, M. S. , Carvalho, M. , Conde-Agudelo, A. , Jaffer, Y. A. , Bertino, E. , Gravett, M. G. , Altman, D. G. , Ohuma, E. O. , Purwar, M. , Frederick, I . O. , Bhutta, Z. A. , Kennedy, S. H. , and Villar, J. , International Fetal and Newborn Growth Consortium for the 21st Century, 2015, “ The Distribution of Clinical Phenotypes of Preterm Birth Syndrome: Implications for Prevention,” JAMA Pediatr., 169(3), pp. 220–229. [CrossRef] [PubMed]
Spong, C. Y. , 2007, “ Prediction and Prevention of Recurrent Spontaneous Preterm Birth,” Obstet. Gynecol., 110(2 Pt. 1), pp. 405–415. [CrossRef] [PubMed]
Iams, J. D. , Goldenberg, R. L. , Meis, P. J. , Mercer, B. M. , Moawad, A. , Das, A. , Thom, E. , McNellis, D. , Copper, R. L. , Johnson, F. , and Roberts, J. M. , 1996, “ The Length of the Cervix and the Risk of Spontaneous Premature Delivery. National Institute of Child Health and Human Development Maternal Fetal Medicine Unit Network,” N. Engl. J. Med., 334(9), pp. 567–573. [CrossRef] [PubMed]
Gardner, M. O. , Goldenberg, R. L. , Cliver, S. P. , Tucker, J. M. , Nelson, K. G. , and Copper, R. L. , 1995, “ The Origin and Outcome of Preterm Twin Pregnancies,” Obstet. Gynecol., 85(4), pp. 553–557. [CrossRef] [PubMed]
Goldenberg, R. L. , Iams, J. D. , Miodovnik, M. , Van Dorsten, J. P. , Thurnau, G. , Bottoms, S. , Mercer, B. M. , Meis, P. J. , Moawad, A. H. , Das, A. , Caritis, S. N. , and McNellis, D. , 1996, “ The Preterm Prediction Study: Risk Factors in Twin Gestations. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network,” Am. J. Obstet. Gynecol., 175(4 Pt. 1), pp. 1047–1053. [CrossRef] [PubMed]
Kirkinen, P. , and Jouppila, P. , 1978, “ Polyhydramnion. A Clinical Study,” Ann. Chir. Gynaecol., 67(3), pp. 117–122. [PubMed]
Chua, W. K. , and Oyen, M. L. , 2009, “ Do We Know the Strength of the Chorioamnion? A Critical Review and Analysis,” Eur. J. Obstet. Gynecol. Reprod. Biol., 144(Suppl. 1), pp. S128–S133. [CrossRef] [PubMed]
Fernandez, M. , House, M. , Jambawalikar, S. , Zork, N. , Vink, J. , Wapner, R. , and Myers, K. , 2015, “ Investigating the Mechanical Function of the Cervix During Pregnancy Using Finite Element Models Derived From High-Resolution 3D MRI,” Comput. Methods Biomech. Biomed. Eng., 19(4), pp. 404–417. [CrossRef]
Arabin, B. , and Alfirevic, Z. , 2013, “ Cervical Pessaries for Prevention of Spontaneous Preterm Birth: Past, Present and Future,” Ultrasound Obstet. Gynecol., 42(4), pp. 390–399. [PubMed]
Goya, M. , Pratcorona, L. , Merced, C. , Rodó, C. , Valle, L. , Romero, A. , Juan, M. , Rodríguez, A. , Muñoz, B. , Santacruz, B. , Bello-Muñoz, J. C. , Llurba, E. , Higueras, T. , Cabero, L. , Carreras, E. , and Pesario Cervical para Evitar Prematuridad (PECEP) Trial Group, 2012, “ Cervical Pessary in Pregnant Women With a Short Cervix (PECEP): An Open-Label Randomised Controlled Trial,” Lancet, 379(9828), pp. 1800–1806. [CrossRef] [PubMed]
Goya, M. , de la Calle, M. , Pratcorona, L. , Merced, C. , Rodó, C. , Muñoz, B. , Juan, M. , Serrano, A. , Llurba, E. , Higueras, T. , Carreras, E. , Cabero, L. , and PECEP-Twins Trial Group, 2016, “ Cervical Pessary to Prevent Preterm Birth in Women With Twin Gestation and Sonographic Short Cervix: A Multicenter Randomized Controlled Trial (PECEP-Twins),” Am. J. Obstet. Gynecol., 214(2), pp. 145–152. [CrossRef] [PubMed]
Nicolaides, K. H. , Syngelaki, A. , Poon, L. C. , de Paco Matallana, C. , Plasencia, W. , Molina, F. S. , Picciarelli, G. , Tul, N. , Celik, E. , Lau, T. K. , and Conturso, R. , 2016, “ Cervical Pessary Placement for Prevention of Preterm Birth in Unselected Twin Pregnancies: A Randomized Controlled Trial,” Am. J. Obstet. Gynecol., 214(1), pp. 3.e1–3.e9. [CrossRef] [PubMed]
Nicolaides, K. H. , Syngelaki, A. , Poon, L. C. , Picciarelli, G. , Tul, N. , Zamprakou, A. , Skyfta, E. , Parra-Cordero, M. , Palma-Dias, R. , and Rodriguez Calvo, J. , 2016, “ A Randomized Trial of a Cervical Pessary to Prevent Preterm Singleton Birth,” N. Engl. J. Med., 374(11), pp. 1044–1052. [CrossRef] [PubMed]
Myers, K. M. , Hendon, C. P. , Gan, Y. , Yao, W. , Yoshida, K. , Fernandez, M. , Vink, J. , and Wapner, R. J. , 2015, “ A Continuous Fiber Distribution Material Model for Human Cervical Tissue,” J. Biomech., 48(9), pp. 1533–1540. [CrossRef] [PubMed]
Yoshida, K. , Mahendroo, M. , Vink, J. , Wapner, R. , and Myers, K. , 2016, “ Material Properties of Mouse Cervical Tissue in Normal Gestation,” Acta Biomater., 36, pp. 195–209. [CrossRef] [PubMed]
Myers, K. , Paskaleva, A. , House, M. , and Socrate, S. , 2008, “ Mechanical and Biochemical Properties of Human Cervical Tissue,” Acta Biomater., 4(1), pp. 104–116. [CrossRef] [PubMed]
Myers, K. , Socrate, S. , Paskaleva, A. , and House, M. , 2010, “ A Study of the Anisotropy and Tension/Compression Behavior of Human Cervical Tissue,” ASME J. Biomech. Eng., 132(2), p. 021003. [CrossRef]
Conrad, J. T. , Johnson, W. L. , Kuhn, W. K. , and Hunter, C. A. , 1966, “ Passive Stretch Relationships in Human Uterine Muscle,” Am. J. Obstet. Gynecol., 96(8), pp. 1055–1059. [CrossRef] [PubMed]
Gan, Y. , Yao, W. , Myers, K. M. , Vink, J. Y. , Wapner, R. J. , and Hendon, C. P. , 2015, “ Analyzing Three-Dimensional Ultrastructure of Human Cervical Tissue Using Optical Coherence Tomography,” Biomed. Opt. Express, 6(4), pp. 1090–1108. [CrossRef] [PubMed]
Yao, W. , Gan, Y. , Myers, K. M. , Vink, J. Y. , Wapner, R. J. , and Hendon, C. P. , 2016, “ Collagen Fiber Orientation and Dispersion in the Upper Cervix of Non-Pregnant and Pregnant Women,” PLOS One, 11(11), p. e0166709. [CrossRef] [PubMed]
Buerzle, W. , and Mazza, E. , 2013, “ On the Deformation Behavior of Human Amnion,” J. Biomech., 46(11), pp. 1777–1783. [CrossRef] [PubMed]
Fisk, N. M. , Ronderos-Dumit, D. , Tannirandorn, Y. , Nicolini, U. , Talbert, D. , and Rodeck, C. H. , 1992, “ Normal Amniotic Pressure Throughout Gestation,” BJOG, 99(1), pp. 18–22. [CrossRef]
Buhimschi, C. S. , Buhimschi, I. A. , Malinow, A. M. , and Weiner, C. P. , 2004, “ Intrauterine Pressure During the Second Stage of Labor in Obese Women,” Obstet. Gynecol., 103(2), pp. 225–230. [PubMed]
Dziadosz, M. , Bennett, T.-A. , Dolin, C. , West Honart, A. , Pham, A. , Lee, S. S. , Pivo, S. , and Roman, A. S. , 2016, “ Uterocervical Angle: A Novel Ultrasound Screening Tool to Predict Spontaneous Preterm Birth,” Am. J. Obstet. Gynecol., 215(3), pp. 376.e1–376.e7. [CrossRef] [PubMed]
de Campos Prado, C. A. , Araujo Júnior, E. , Duarte, G. , Quintana, S. M. , Tonni, G. , de Carvalho Cavalli, R. , and Marcolin, A. C. , 2016, “ Predicting Success of Labor Induction in Singleton Term Pregnancies by Combining Maternal and Ultrasound Variables,” J. Matern.-Fetal Neonat. Med., 29(21), pp. 3511–3518.
Gillespie, E. C. , 1950, “ Principles of Uterine Growth in Pregnancy,” Am. J. Obstet. Gynecol., 59(5), pp. 949–959. [CrossRef] [PubMed]
House, M. , and Socrate, S. , 2006, “ The Cervix as a Biomechanical Structure,” Ultrasound Obstet. Gynecol., 28(6), pp. 745–749. [CrossRef] [PubMed]
House, M. , McCabe, R. , and Socrate, S. , 2013, “ Using Imaging-Based, Three-Dimensional Models of the Cervix and Uterus for Studies of Cervical Changes During Pregnancy,” Clin. Anat., 26(1), pp. 97–104. [CrossRef] [PubMed]
Sokolowski, P. , Saison, F. , Giles, W. , McGrath, S. , Smith, D. , Smith, J. , and Smith, R. , 2010, “ Human Uterine Wall Tension Trajectories and the Onset of Parturition,” PLOS One, 5(6), p. e11037. [CrossRef] [PubMed]
Danforth, D. N. , 1947, “ The Fibrous Nature of the Human Cervix, and Its Relation to the Isthmic Segment in Gravid and Nongravid Uteri,” Am. J. Obstet. Gynecol., 53(4), pp. 541–560. [CrossRef] [PubMed]
Fisk, N. M. , Tannirandorn, Y. , Nicolini, U. , Talbert, D. G. , and Rodeck, C. H. , 1990, “ Amniotic Pressure in Disorders of Amniotic Fluid Volume,” Obstet. Gynecol., 76(2), pp. 210–214. [PubMed]
Nicolini, U. , Fisk, N. M. , Talbert, D. G. , Rodeck, C. H. , Kochenour, N. K. , Greco, P. , Hubinont, C. , and Santolaya, J. , 1989, “ Intrauterine Manometry: Technique and Application to Fetal Pathology,” Prenatal Diagn., 9(4), pp. 243–254. [CrossRef]
Cunningham, F. G. , Leveno, K. J. , Bloom, S. L. , Spong, C. Y. , Dashe, J. S. , Hoffman, B. L. , Casey, B. M. , and Sheffield, J. S. , 2014, “ Maternal Physiology,” Williams Obstetrics, 24th ed., McGraw-Hill Education/Medical, New York, Ch. 5.
Martini, F. H. , Nath, J. L. , and Bartholomew, E. F. , 2014, “ Development and Inheritance,” Fundamentals of Anatomy & Physiology, 24th ed., Pearson, Glenview, IL, Ch. 29.
Degani, S. , Leibovitz, Z. , Shapiro, I. , Gonen, R. , and Ohel, G. , 1998, “ Myometrial Thickness in Pregnancy: Longitudinal Sonographic Study,” J. Ultrasound Med., 17(10), pp. 661–665. [CrossRef] [PubMed]
Buhimschi, C. S. , Buhimschi, I . A. , Malinow, A. M. , and Weiner, C. P. , 2003, “ Myometrial Thickness During Human Labor and Immediately Post Partum,” Am. J. Obstet. Gynecol., 188(2), pp. 553–559. [CrossRef] [PubMed]
Buhimschi, C. S. , Buhimschi, I. A. , Norwitz, E. R. , Sfakianaki, A. K. , Hamar, B. , Copel, J. A. , Saade, G. R. , and Weiner, C. P. , 2005, “ Sonographic Myometrial Thickness Predicts the Latency Interval of Women With Preterm Premature Rupture of the Membranes and Oligohydramnios,” Am. J. Obstet. Gynecol., 193(3), pp. 762–770. [CrossRef] [PubMed]
Durnwald, C. P. , and Mercer, B. M. , 2008, “ Myometrial Thickness According to Uterine Site, Gestational Age and Prior Cesarean Delivery,” J. Matern.-Fetal Neonat. Med., 21(4), pp. 247–250. [CrossRef]
Yoshida, M. , Sagawa, N. , Itoh, H. , Yura, S. , Takemura, M. , Wada, Y. , Sato, T. , Ito, A. , and Fujii, S. , 2002, “ Prostaglandin F2α, Cytokines and Cyclic Mechanical Stretch Augment Matrix Metalloproteinase-1 Secretion From Cultured Human Uterine Cervical Fibroblast Cells,” Mol. Hum. Reprod., 8(7), pp. 681–687. [CrossRef] [PubMed]
Takemura, M. , Itoh, H. , Sagawa, N. , Yura, S. , Korita, D. , Kakui, K. , Hirota, N. , and Fujii, S. , 2004, “ Cyclic Mechanical Stretch Augments Both Interleukin-8 and Monocyte Chemotactic Protein-3 Production in the Cultured Human Uterine Cervical Fibroblast Cells,” Mol. Hum. Reprod., 10(8), pp. 573–580. [CrossRef] [PubMed]
Takemura, M. , Itoh, H. , Sagawa, N. , Yura, S. , Korita, D. , Kakui, K. , Kawamura, M. , Hirota, N. , Maeda, H. , and Fujii, S. , 2005, “ Cyclic Mechanical Stretch Augments Hyaluronan Production in Cultured Human Uterine Cervical Fibroblast Cells,” Mol. Hum. Reprod., 11(9), pp. 659–665. [CrossRef] [PubMed]
Society for Maternal-Fetal Medicine Publications Committee, With Assistance of Vincenzo Berghella, 2012, “ Progesterone and Preterm Birth Prevention: Translating Clinical Trials Data Into Clinical Practice,” Am. J. Obstet. Gynecol., 206(5), pp. 376–386. [CrossRef] [PubMed]
Iams, J. , Johnson, F. , Sonek, J. , Sachs, L. , Gebauer, C. , and Samuels, P. , 1995, “ Cervical Competence as a Continuum: A Study of Ultrasonographic Cervical Length and Obstetric Performance,” Am. J. Obstet. Gynecol., 172(4 Pt. 1), pp. 1097–1106. [CrossRef] [PubMed]
Guzman, E. R. , Mellon, R. , Vintzileos, A. M. , Ananth, C. V. , Walters, C. , and Gipson, K. , 1998, “ Relationship Between Endocervical Canal Length Between 15–24 Weeks Gestation and Obstetric History,” J. Matern.-Fetal Med., 7(6), pp. 269–272. [PubMed]
Guzman, E. R. , Walters, C. , Ananth, C. V. , O'Reilly-Green, C. , Benito, C. W. , Palermo, A. , and Vintzileos, A. M. , 2001, “ A Comparison of Sonographic Cervical Parameters in Predicting Spontaneous Preterm Birth in High-Risk Singleton Gestations,” Ultrasound Obstet. Gynecol., 18(3), pp. 204–210. [CrossRef] [PubMed]
Moroz, L. A. , and Simhan, H. N. , 2012, “ Rate of Sonographic Cervical Shortening and the Risk of Spontaneous Preterm Birth,” Am. J. Obstet. Gynecol., 206(3), pp. 234.e1–234.e5. [CrossRef] [PubMed]
Romero, J. , Rebarber, A. , Saltzman, D. H. , Schwartz, R. , Peress, D. , and Fox, N. S. , 2012, “ The Prediction of Recurrent Preterm Birth in Patients on 17-Alpha-Hydroxyprogesterone Caproate Using Serial Fetal Fibronectin and Cervical Length,” Am. J. Obstet. Gynecol., 207(1), pp. 51.e1–51.e5. [CrossRef] [PubMed]
Melamed, N. , Hiersch, L. , Domniz, N. , Maresky, A. , Bardin, R. , and Yogev, Y. , 2013, “ Predictive Value of Cervical Length in Women With Threatened Preterm Labor,” Obstet. Gynecol., 122(6), pp. 1279–1287. [CrossRef] [PubMed]
Bastek, J. A. , Hirshberg, A. , Chandrasekaran, S. , Owen, C. M. , Heiser, L. M. , Araujo, B. A. , McShea, M. A. , Ryan, M. E. , and Elovitz, M. A. , 2013, “ Biomarkers and Cervical Length to Predict Spontaneous Preterm Birth in Asymptomatic High-Risk Women,” Obstet. Gynecol., 122(2 Pt. 1), pp. 283–289. [CrossRef] [PubMed]
Sananes, N. , Langer, B. , Gaudineau, A. , Kutnahorsky, R. , Aissi, G. , Fritz, G. , Boudier, E. , Viville, B. , Nisand, I. , and Favre, R. , 2014, “ Prediction of Spontaneous Preterm Delivery in Singleton Pregnancies: Where Are We and Where Are We Going? A Review of Literature,” J. Obstet. Gynaecol., 34(6), pp. 457–461. [CrossRef] [PubMed]
Uquillas, K. R. , Fox, N. S. , Rebarber, A. , Saltzman, D. H. , Klauser, C. K. , and Roman, A. S. , 2016, “ A Comparison of Cervical Length Measurement Techniques for the Prediction of Spontaneous Preterm Birth,” J. Matern.-Fetal Neonat. Med., 30(1), pp. 50–53. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Uterine and cervical dimensions taken via transabdominal and transperineal ultrasound at 25 weeks of gestation. UD: uterine diameter, UT: uterine thickness, CD: cervical dimension, and CA: cervical angle.

Grahic Jump Location
Fig. 2

Three-dimensional representation of the environment of pregnancy. The cervix was separated into three sections for analysis: the upper cervix, lower cervix, and internal os region.

Grahic Jump Location
Fig. 3

Sample mesh for baseline geometry. The fetal membrane was meshed with hexahedral elements, while all other volumes were meshed with tetrahedral elements.

Grahic Jump Location
Fig. 4

Boundary and loading conditions. Outside of abdomen was fixed in x, y, and z directions (dashed lines in figure). Uniform intrauterine pressure (IUP) was applied on inner surface of FM. Tied contact was applied between FM (cyan) and uterine wall (purple) and between FM and upper cervix (green). Sliding contact was applied between FM and cervix internal os region (yellow). (For interpretation of the color in this figure legend, the reader is referred to the web version of this article.)

Grahic Jump Location
Fig. 5

The color map reports the first principal right stretch for the baseline geometry evaluated with IUPs of (a) 25 weeks = 0.817 kPa, (b) 40 week = 2.33 kPa, and (c) contraction = 8.67 kPa. The percentage reports the volume fraction of the cervical internal os region above a 1.05 stretch. The membrane is removed for clarity. (For interpretation of the color in this figure legend, the reader is referred to the web version of this article.)

Grahic Jump Location
Fig. 6

Baseline results with vector plots to show stretch directions for (a) first principal right stretch, (b) second principal right stretch, (c) third principal right stretch, and (d) maximum shear strain. For first principal right stretch, circumferential stretch is exhibited at the internal os while radial stretch is observed at the anterior and posterior sections of the uterocervical interface.

Grahic Jump Location
Fig. 7

Uterine and cervical stretch patterns as AUCA (shown top left) is varied. The color map reports the first principal right stretch for not remodeled cervix with AUCA of (a) 90 deg, (b) 100 deg, and (c) 110 deg, and remodeled cervix with AUCA of (d) 90 deg, (e) 100 deg, and (f) 110 deg. The percentage reports the volume fraction of the cervical internal os region above a 1.05 stretch. The membrane is removed for clarity. (For interpretation of the color in this figure legend, the reader is referred to the web version of this article.)

Grahic Jump Location
Fig. 8

Uterine and cervical stretch patterns as CL (shown top left) is varied. The color map reports the first principal right stretch for not remodeled cervix with CL of (a) 25 mm, (b) 30 mm, (c) 35 mm, and (d) 40 mm, and remodeled cervix with CL of (e) 25 mm, (f) 30 mm, (g) 35 mm, and (h) 40 mm. The percentage reports the volume fraction of the cervical internal os region above a 1.05 stretch. The membrane is removed for clarity. (For interpretation of the color in this figure legend, the reader is referred to the web version of this article.)

Grahic Jump Location
Fig. 9

Uterine and cervical stretch patterns as PCO (shown top left) is varied. The color map reports the first principal right stretch for not remodeled cervix with PCO of (a) 0 mm, (b) 5 mm, (c) 10 mm, (d) 15 mm, (e) 20 mm, and (f) 25 mm, and remodeled cervix with PCO of (g) 0 mm, (h) 5 mm, (i) 10 mm, (j) 15 mm, (k) 20 mm, and (l) 25 mm. The percentage reports the volume fraction of the cervical internal os region above a 1.05 stretch. The membrane is removed for clarity. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Grahic Jump Location
Fig. 10

Uterine and cervical stretch patterns as cervical fiber stiffness is varied. The color map reports the first principal right stretch for the baseline geometry evaluated with a cervical fiber stiffness (ξ) value of (a) 1.71, (b) 7.89, (c) 36.3, (d) 167, and (e) 769 kPa. The percentage reports the volume fraction of the cervical internal os above a 1.05 stretch. The membrane is removed for clarity. (For interpretation of the color in this figure legend, the reader is referred to the web version of this article.)

Grahic Jump Location
Fig. 11

Principal right stretch plots of the MRI geometry model (a1) and the parameterized geometry model (a2) under an IUP of 0.817 kPa applied to the fetal membrane. First principal stretches ((a1) and (a2)) reflect the areas of highest tension and are concentrated around the internal os and the proximal portion of the cervix. Third principal strains ((c1) and (c2)) represent areas of compression, which are most prominent in the MRI model (c1). Shear strains are shown in figures (d) and are also concentrated over the internal os, but are approximately twice as large in the MRI-derived model due to the irregular surface of the geometry.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In