(854) Development of a benchtop model of cervical laceration with cerclage in situ

Our long-term objective is the development of a novel medical device as a cerclage alternative. Cervical laceration is a known complication of cerclage. One goal of the medical device is to reduce the risk of cervical laceration. However, no benchtop model of cervical laceration exists. Thus, we sought to develop a three-dimensional (3D) benchtop model to study cervical laceration using a silicone-based cervix that mimics the stiffness of the human cervix in pregnancy.

Study Design:

 The silicone cervix model consisted of two parts (see “Cervix” image in Figure). The upper part (blue color) was composed of Smooth-Sil 950 (Smooth-On, Macungie, PA). The lower part (the cervix, tan color) was composed of Ecoflex, a soft silicone (Smooth-On). The silicone cervix formula was selected to match the mechanical properties of human cervical tissue based on pilot studies, as follows: 1-part Ecoflex 00-30 Part A; 1-part Ecoflex Part B; 3-parts SmoothOn silicone thinner . Ecoflex was first poured into the bottom portion of a 3D printed mold and cured to make the silicone cervix. Next,  Smooth Sil 950 was added to fill the mold. The stiffness of the silicone cervix was tested with the Pregnolia system (Pregnolia, Switzerland)(N=9). To assess cervical laceration, the silicone cervix was mounted on a test fixture attached to an Instron machine. A 3D printed fetal head (diameter 8.9 cm) was pushed through the silicone cervix (Figure, top right)(N=6). Outcomes were compared between silicone cervices with no cerclage and with an O-Vicryl cerclage suture. Silicone tearing was used as an estimate of the risk of cervical laceration

Results:

The mean (± SD) stiffness of the silicone cervix was 168 ± 17 millibar, which is similar to the stiffness of the human cervix in previously published studies. Silicone cervices without a cerclage had no tearing. However, tearing occurred in all silicone cervices with a cerclage in place (P = 0.002).

Conclusion:

 We designed a benchtop model that reliably simulates cervical laceration, which can be used to study alternate devices for the treatment of cervical insufficiency.