Addition of Buprenorphine to Paracervical Block for Pain Control During Osmotic Dilator Insertion

Cervical preparation with osmotic dilators is commonly used prior to dilation and evacuation (D\&E) procedures to decrease the risk of complications. Women have described the pain of osmotic dilator insertion as moderate to severe yet there have been few studies aimed at addressing pain during and after osmotic dilator insertion. In addition to the discomfort during insertion, pain after osmotic dilator insertion peaks at 2 hours post-insertion with use of a lidocaine paracervical block. One randomized trial found that use of a paracervical block with 1% buffered lidocaine decreased pain with osmotic dilator insertion compared to a sham block. There are adjunct treatments to optimize analgesia with local anesthetics at a variety of anatomic locations. Buprenorphine, a partial mu-opioid receptor agonist, has been found to increase the quality of the anesthetic at the time of administration and increase the duration of nerve block analgesia at several anatomic sites, though has never been studied as an adjunct in a paracervical block. This has been used extensively in orthopedic surgery with significant prolongation of the local anesthetic effect by almost threefold in some studies. Primary Aim: To compare the mean pain score at the time of osmotic dilator insertion among women randomized to a 1% lidocaine and buprenorphine paracervical block compared to a 1% lidocaine paracervical block alone. Secondary Aim: To compare the mean pain score 2 hours after osmotic dilator insertion among women randomized to a lidocaine and buprenorphine paracervical block compared to a lidocaine paracervical block alone. The investigators hypothesize that in patients undergoing osmotic dilator insertion in preparation for dilation and evacuation, the addition of buprenorphine 0.15mg to a 1% lidocaine paracervical block will be associated with lower mean pain scores at time of osmotic dilator insertion compared to women who receive a 1% lidocaine paracervical block alone.