S. G. Kunz1, N. Katta2, Y. Tadir2, J. T. Nahmias1, T. E. Milner2, L. Swentek1,2 1University Of California – Irvine, Surgery Dept., Orange, CA, USA 2University Of California – Irvine, Beckman Laser Institute, Orange, CA, USA
Introduction: Over 3 million babies are born each year in the United States, during which patients in labor undergo serial cervical examinations. This consists of a provider inserting a gloved hand into the vagina to measure the dilation, effacement, station, consistency, and position of the cervix. Together these measurements compose the Bishop score, the current standard for determining progression of labor. However, these exams are invasive, and can be painful with increased risk of infection. In addition, the exams are subject to intra/inter-examiner variability and may cause premature rupture of membranes. As such, there is a need for a minimally invasive alternative that provides real-time monitoring of cervical change during labor and delivery. As such we aimed to develop a novel device that incorporates a small caliber linear ultrasound (US) probe within a urinary catheter (Figure 1A) to monitor changes of the cervix as a solution to avoid painful, invasive, and subjective cervical exams. This study sought to test proof of concept using a porcine model.
Methods: An initial working prototype was constructed using a tri- lumen configuration with the urinary catheter balloon, the US transducer, and a patent lumen (Figure 1B). Initial proof-of-concept testing for the US probe was performed using in vitro porcine genitourinary system tissue on July 28, 2022. The primary endpoint was visualization of the cervical os with the prototype US probe inserted into the urinary bladder with accurate measurement of cervical dilation using a Foley balloon inserted into the cervical os.
Results: This prospective proof of concept study of a porcine model was performed five times. From the conducted experiments, there was confirmed visualization of the cervix 5 out of 5 attempts (100%) and accurate measurements of dilation from 0 to 25 mm (Figure 1C).
Conclusion: This in vitro porcine proof-of-concept test of a novel prototype to provide real-time cervical monitoring met initial endpoints of visualization of the cervical os and accurate measurement of dilation. Next, the prototype will undergo full engineering specification testing including flow rate testing to ensure adequate function of the urinary catheter while the cervical monitoring is functional. Additional research will include testing for the feasibility of concurrent fetal heart rate monitoring via doppler.
