Hyperelastic Mechanical Properties of Ex Vivo Normal and Intrauterine Growth Restricted Placenta
Intrauterine Growth Restriction (IUGR) is a serious and prevalent pregnancy complication that is due to placental insufficiency and IUGR babies suffer significantly higher risks of mortality and morbidity. Current detection rate for IUGR is generally poor and thus an alternative diagnostic tool is needed to improve the IUGR detection. Elastography, a non-invasive method that measures the tissue stiffness, has been proposed as one such technique. However, to date, we have limited information on the mechanical properties of IUGR placenta. In this study, we investigated the mechanical properties of normal and IUGR placentae and prescribed a suitable hyperelastic model to describe their mechanical behaviors. A total of 46 normal and 43 IUGR placenta samples were investigated. Results showed that placenta samples were isotropic, but had a high spatial variability of stiffness. The samples also had significant viscoelasticity. IUGR placenta was observed to be slightly stiffer than normal placenta but the difference was significant only at compression rate of 0.25 Hz and with 20% compression depth. Three simple hyperelastic models—Yeoh, Ogden and Fung models, were found to be able to fit the experimentally measured mechanical behaviors, and Fung model performed slightly better. These results may be useful for optimizing placenta elastography for the detection of IUGR.
KeywordsPlacenta mechanical properties Intrauterine growth restriction Fetal growth restriction 3D hyperelastic model Uniaxial mechanical testing
This research was supported by the National University of Singapore Young Investigator Award 2015 (PI: Yap) and the Ministry of Education of Singapore Academic Research Fund Tier 1 Grant entitled “Placenta Blood Oxygen Monitor for Intrauterine Growth Restriction Pregnancies (PI: Yap). We would like to express our gratitude to Cecille Arquillo Laureano, Cynthia Pamela Zapata Tagarino, Maylene Zipagan and other staff members from Obstetrics & Gynecology Department at National University Hospital for their assistance with patient eligibility and tissue procurement.
Conflict of interest
All authors have no conflict of interest to declare.
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