Model of Lidocaine Diffusion Through Cervix Improving Patient Experiences During Routine Gynecological Procedures

Intrauterine devices, or IUDs, are long-lasting forms of birth control that have effectiveness comparable to sterilization, while they can be removed at any time. However, the insertion process can be very painful, especially for individuals who have never given vaginal birth. The most common form of pain management for this procedure is having the patient take an ibuprofen an hour or so before the procedure, but this only helps with cramping afterwards, not the acute pain caused by insertion. Pain, and anxiety and fear regarding potential pain, serve as a barrier between users and this highly effective form of birth control. This report uses COMSOL to model lidocaine diffusion from 4% topical hydrogel into the cervix (the main site of acute pain during IUD insertion) over 180 minutes. The cervix was modeled axisymmetrically, using average experimental values for cervix size. Concentration at four specific probe points were measured over time and compared at different concentrations. A sensitivity analysis was performed by adjusting the diffusion coefficient of the epithelial layer. This model was developed to serve as a predictor for future drug applications across the cervix, to determine in advance whether a novel formulation of drug would be effective to significantly reduce pain. This model may be refined further with experimental values for the constants, and with further testing of different lidocaine concentrations.