Optimization of injections with speculum-compatible devices to deliver ethyl cellulose-ethanol into the cervix to treat cervical dysplasia

Intracervical injections directly delivery therapies into the cervix. We previously explored ethyl cellulose (EC)-ethanol intracervical injections as a treatment for cervical dysplasia in low- and middle-income countries. Here we: 1) compared swine and human cervices to assess swine as a model for intracervical injections, and 2) evaluated two speculum-compatible injectors: a custom single needle injector and an extender injector, assembled from off-the-shelf components, to determine what parameters produced optimal distribution. Mechanical properties of swine and human cervices were compared. Swine cervices were injected with EC-ethanol iohexol using both injectors. Distribution and leakage volumes in tissue was visualized with microCT and quantified with 3D Slicer. Mechanical testing showed swine and human cervical tissue yielded comparable storage and loss moduli (p > 0.05). Ex vivo studies showed injections ≥ 10 mm deep and < 2 mL significantly reduced backflow and crack formation for both injectors. Additionally, the extender injector produced significantly less crack formation than the single needle injector. These findings indicate swine cervices are a clinically relevant model for intracervical injection studies. The extender device when inserted ≥ 10 mm and delivering < 2 mL of EC-ethanol achieved the most consistent results across intracervical delivery protocols.