Device Prototype for Vaginal Delivery of Extremely Preterm Fetuses in the Breech Presentation

Mallory Whalen; Elizabeth Chang-Davidson; Terra Moran; Rachel Hoffman; Galit H Frydman; Alexander Slocum; Alissa Dangel

doi:10.1115/1.4049086

Device Prototype for Vaginal Delivery of Extremely Preterm Fetuses in the Breech Presentation

J Med Device. 2021 Jun 1;15(2):021002. doi: 10.1115/1.4049086. Epub 2020 Dec 18.

Authors

Mallory Whalen¹, Elizabeth Chang-Davidson², Terra Moran³, Rachel Hoffman¹, Galit H Frydman⁴, Alexander Slocum¹, Alissa Dangel⁵

Affiliations

¹ Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
² Department of Mechanical Engineering,Carnegie Mellon University, Pittsburgh, PA 15213; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
³ Master in Design Engineering Program, Harvard University, Cambridge, MA 02138.
⁴ Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; Department of Surgery, Massachusetts General Hospital, Boston, MA 02114.
⁵ TL1 Clinical Research Fellow, Tufts Medical Center-CTSI, Boston, MA 02111.

Abstract

Vaginal delivery is typically avoided in the extremely preterm breech population due to the concern of entrapment by the cervix of the aftercoming head. A mechanical device concept is presented to enable vaginal delivery by preventing retraction of the cervix against the fetus during delivery. The two-part device was designed to dilate the cervix, prevent prolapse of small fetal parts and maintain sufficient dilation during delivery. The two-part device was designed and manufactured with the following modules: an inflatable saline-filled cervical balloon for dilation and a cervical retractor composed of semirigid beams to stabilize the cervix and maintain adequate dilation. The device was tested using a cervical phantom designed to simulate the compressive force the cervix exerts. The cervical balloon reached a maximum dilation of 8.5 cm, after which there was leakage of saline from the balloon. While this dilation was less than the target goal of 10 cm, the leaking was attributed to prototype manufacturing defects, which could be resolved with further development. The cervical retractor was able to withstand between 1-3 kPa. Although estimates of cervical pressure values can be upward of 30 kPa, there are no in vivo measurements to formally identify the pressure values for patients in preterm labor. This device serves as a viable proof-of-concept for utilizing an inflatable balloon device to prevent cervical retraction in the setting of extremely preterm vaginal breech delivery. Further manufacturing improvements and design changes could improve the device for continued development and testing.