Gabapentin as an adjunct to paracervical block for perioperative pain management for first-trimester uterine aspiration: a randomized controlled trial.

ABSTRACT

BACKGROUND: Pain management approaches during uterine aspiration vary, which include local anesthetic, oral analgesics, moderate sedation, deep sedation, or a combination of approaches. For local anesthetic approaches specifically, we continue to have suboptimal pain control. Gabapentin as an adjunct to pain management has proven to be beneficial in gynecologic surgery. We sought to evaluate the impact of gabapentin on perioperative pain during surgical management of first-trimester abortion or early pregnancy loss with uterine aspiration under local anesthesia. OBJECTIVE: We hypothesized that adding gabapentin to local anesthesia will reduce perioperative and postoperative pain associated with uterine aspiration. Secondary outcomes included tolerability of gabapentin and postoperative pain, nausea, vomiting, and anxiety. STUDY DESIGN: We conducted a randomized double-blinded placebo-controlled trial of gabapentin 600 mg given 1 to 2 hours preoperatively among subjects receiving a first-trimester uterine aspiration under paracervical block in an outpatient ambulatory surgery center. There were 111 subjects randomized. The primary outcome was pain at time of uterine aspiration as measured on a 100-mm visual analog scale. Secondary outcomes included pain at other perioperative time points. To assess changes in pain measures, an intention to treat mixed effects model was fit with treatment groups (gabapentin vs control) as a between-subjects factor and time point as a within-subjects factor plus their interaction term. Because of a non-normal distribution of pain scores, the area under the curve was calculated for secondary outcomes with comparison of groups utilizing Mann-Whitney U tests. RESULTS: Among the 111 randomized, most subjects were Black or African American (69.4%), mean age was 26 years (±5.5), and mean gestational age was 61.3 days (standard deviation, 14.10). Mean pain scores at time of uterine aspiration were 66.77 (gabapentin) vs 71.06 (placebo), with a mean difference of -3.38 (P=.51). There were no significant changes in pain score preoperatively or intraoperatively. Subjects who received gabapentin had significantly lower levels of pain at 10 minutes after surgery (mean difference [standard error (SE)]=-13.0 [-5.0]; P=.01) and 30 minutes after surgery (mean difference [SE]=-10.8 [-5.1]; P=.03) compared with subjects who received placebo. Median nausea scores and incidence of emesis pre- and postoperatively did not differ between groups. Similarly, anxiety scores did not differ between groups, before or after the procedure. At 10 and 30 minutes after the procedure, most participants reported no side effects or mild side effects, and this did not differ between groups. CONCLUSION: Preoperative gabapentin did not reduce pain during uterine aspiration. However, it did reduce postoperative pain, which may prove to be a desired attribute of its use, particularly in cases where postoperative pain may be a greater challenge.