By Rebecca H. Allen, MD, MPH
Associate Professor, Department of Obstetrics and Gynecology, Warren Alpert Medical School of Brown University, Women and Infants Hospital, Providence, RI
Dr. Allen reports she receives grant/research support from Bayer and is a consultant for Merck.
SYNOPSIS: In this randomized, double-blind, placebo-controlled trial, 600 mg of oral gabapentin administered one to two hours pre-procedure did not reduce pain during or after first-trimester surgical abortion.
SOURCE: Gray BA, Hagey JM, Crabtree D, et al. Gabapentin for perioperative pain management for uterine aspiration: A randomized controlled trial. Obstet Gynecol 2019;134:611-619.
The authors conducted a randomized, double-blind, controlled trial that compared 600 mg of gabapentin and placebo administered for pain control one to two hours before first-trimester uterine aspiration in the office setting. Eligible participants were English-speaking, adult women between 6 0/7 and 14 6/7 weeks gestation. Exclusion criteria included allergy to study medications, current use of gabapentin or pregabalin, and severe renal disease. As part of standard of care at the site, participants also received 2 mg lorazepam, 325 mg acetaminophen/5 mg oxycodone, and 800 mg ibuprofen, as well as a 40 mL 0.5% lidocaine paracervical block. Women between 12 0/7 weeks and 14 6/7 weeks received 400 mcg of vaginal misoprostol two hours beforehand. Manual vacuum aspiration was used for women < 12 weeks gestation, and electric suction was used for all others. Pain scores on a 100 mm visual analog scale were collected throughout the procedure and postoperatively at five, 10, and 30 minutes, and at 24 hours. Researchers also collected data about side effects and pain medications used up to 24 hours post-procedure. The primary outcome was pain score five minutes after removal of the speculum.
A total of 96 women were randomized between August 2016 and June 2018 at the Duke University Gynecology Outpatient Clinic. There was no difference between the two groups in terms of parity, history of vaginal birth, history of anxiety, and baseline pain. There was no difference in pain score, controlling for baseline pain, five minutes after removal of the speculum between the two groups (37.1 ± 30.4 gabapentin vs. 35.7 ± 27.5 placebo; P = 0.56). There was also no difference in pain scores between the groups in terms of speculum insertion, paracervical block, cervical dilation, uterine aspiration five, 10, and 30 minutes and 24 hours postoperatively. Approximately 75% of participants received a prescription for 325 mg acetaminophen/5 mg oxycodone after the procedure. The only significant difference was that fewer women in the gabapentin group used this opiate medication (18% vs. 47%; P = 0.01) compared to the placebo group in the first 24 hours postoperatively. There was no difference between the two groups in ibuprofen use (49% vs. 48%; P = 0.92) during this time period.
COMMENTARY
Gabapentin, an anticonvulsant, has been used for the treatment of chronic neuropathic pain as well as for postoperative pain as part of enhanced recovery after surgery algorithms.1 Gabapentin has been shown to reduce postoperative pain and opioid consumption after a variety of surgical procedures, but also causes sedation and dizziness.1-3 The authors of this study sought to determine if gabapentin could augment pain control during uterine aspiration procedures under local anesthesia with oral sedation. They hypothesized that gabapentin could be a useful adjunct that would avoid the use of additional opioids. There has been little research conducted on the use of gabapentin for office-based surgery.
Previous studies evaluating adjunctive medications for pain control during uterine aspiration under local anesthesia alone have not shown much benefit for any medication other than nonsteroidal anti-inflammatory drugs, such as ibuprofen.4 While we know that intravenous moderate and deep sedation can treat pain adequately for these procedures, there is little evidence that preoperative oral anxiolytics or opioid pain medications actually affect intraoperative pain. They may have benefit in reducing postoperative pain and anxiety, however. The ideal pain regimen for uterine aspiration in the office has yet to be determined. Nevertheless, there is likely a need for a multimodal approach that includes ibuprofen, paracervical block, and a supportive, comforting environment, which may include a dedicated support person.4 This study shows that gabapentin does not add anything to the experience of pain during or after the procedure in this setting.
Given what we know about gabapentin, I am not sure I would have expected it to work for acute intraoperative pain, but it also did not work for pain in the first 24 hours post-procedure. The authors confirmed an effect documented in previous studies, namely that gabapentin decreases opioid usage in the postoperative period. However, pain medication containing opioids rarely is prescribed for postoperative pain after first-trimester uterine aspiration, and therefore it is unclear whether this finding is generalizable. It is likely that gabapentin adds little to the pain management of minor office-based procedures.
REFERENCES
- Hurley RW, Cohen SP, Williams KA, et al. The analgesic effects of perioperative gabapentin on postoperative pain: A meta-analysis. Reg Anesth Pain Med 2006;31:237-247.
- Tiippana EM, Hamunen K, Kontinen VK, Kalso E. Do surgical patients benefit from perioperative gabapentin/pregabalin? A systematic review of efficacy and safety. Anesth Analg 2007;104:1545-1556.
- Alayed N, Alghanaim N, Tan X, Tulandi T. Preemptive use of gabapentin in abdominal hysterectomy: A systematic review and meta-analysis. Obstet Gynecol 2014;123:1221-1229.
- Renner RM, Jensen JT, Nichols MD, Edelman A. Pain control in first trimester surgical abortion. Cochrane Database Syst Rev 2009 Apr 15;(2):CD006712.
