Pain control in first-trimester surgical abortion: a systematic review of randomized controlled trials

Abstract

Background

First-trimester abortions especially cervical dilation and suction aspiration are associated with pain despite various methods of pain control.

Study Design

Following the guidelines for a Cochrane review, we systematically searched for and reviewed randomized controlled trials comparing methods of pain control in first-trimester surgical abortion at less than 14 weeks gestational age using electric or manual suction aspiration. Outcomes included intra- and postoperative pain, side effects, recovery measures and satisfaction.

Results

We included 40 trials with 5131 participants. Because of heterogeneity, we divided studies into seven groups:

Local anesthesia: Data were insufficient to show a clear benefit of a paracervical block (PCB) compared to no PCB. Reported mean pain scores (10-point scale) during dilation and aspiration were improved with carbonated lidocaine [weighted mean difference (WMD), −0.80; 95% confidence interval (CI), −0.89 to −0.71; WMD, −0.96; 95% CI, −1.67 to −0.25], deep injection (WMD, −1.64; 95% CI, −3.21 to −0.08; WMD, 1.00; 95% CI, 1.09 to 0.91), and with adding a 4% intrauterine lidocaine infusion (WMD, −2.0; 95% CI, −3.29 to −0.71; WMD, −2.8; 95% CI, −3.95 to −1.65).

PCB with premedication: Ibuprofen and naproxen resulted in small reduction of intra- and postoperative pain.

Conscious sedation: The addition of conscious intravenous sedation using diazepam and fentanyl to PCB decreased procedural pain.

General anesthesia: Conscious sedation increased intraoperative but decreased postoperative pain compared to general anesthesia (GA) [Peto odds ratio (Peto OR) 14.77 (95%, CI 4.91–44.38) and Peto OR 7.47 (95% CI, 2.2–25.36) for dilation and aspiration, respectively, and WMD −1.00 (95% CI, −1.77 to −0.23) postoperatively). Inhalation anesthetics are associated with increased blood loss (p<0.001).

GA with premedication: The cyclooxygenase (COX)-2 inhibitor etoricoxib; the nonselective COX inhibitors lornoxicam, diclofenac and ketorolac IM; and the opioid nalbuphine improved postoperative pain.

Nonpharmacological intervention: Listening to music decreased procedural pain.

No major complication was observed.

Conclusions

Conscious sedation, GA and some nonpharmacological interventions decreased procedural and postoperative pain, while being safe and satisfactory to patients. Data on the widely used PCB are inadequate to support its use, and it needs to be further studied to determine any benefit.

Introduction

Elective abortions are among the most common outpatient surgical procedures performed on women with an estimated 46 million performed yearly worldwide [1]. Nearly 90% are performed in the first trimester before 13 weeks gestation [2]. A major complication occurs in less than 1 in 100 women and mortality is around 0.7 in 100,000 [3], [4], [5]. Complications from all forms of anesthesia accounted for 16% of all legally induced abortion mortality in the United States in the years 1988 to 1997, a marked decrease from the 29% attributable to general anesthesia (GA) alone reported for 1983 to 1987 [4], [6].

Anesthesia is important for women undergoing an abortion since most will experience pain with the procedure. Key factors that influence the choice of anesthesia or analgesia include effectiveness, safety, side effects and costs. Other important factors include patient preference, practitioner choice or bias, facility resources and medical indications [7].

Pain perception is a complex phenomenon composed of both physical and psychosocial elements and their interaction, and varies considerably among women [8]. The physical pain associated with abortion most likely originates from the S2 to S4 parasympathetic fibers (the Frankenhäuser plexus) that innervate the cervix and the lower part of the uterine body [9], [10]. In addition, the fundus and lower part of uterine body are innervated by sympathetic fibers from T10 to L1 via the inferior hypogastric nerve and the ovarian plexus [7].

Additionally, psychological (affective, motivational, interpretive) and social (context, support) features play into pain perception [11]. Increased pain with abortion has been associated with young age, nulliparity, less education, anxiety, depression, “moral problems” (with the procedure), a retroverted uterus and dysmenorrhea [12], [13]. A history of prior vaginal delivery correlates well with decreased pain [12]. Data on the relationship between pain and gestational age, as well as the amount of cervical dilation performed, have been conflicting [11], [12], [14].

Due to this complex nature, effective management of abortion-related pain requires a combination of pharmacological and nonpharmacological methods [7]. Pharmacological methods include local anesthetic, nonsteroidal anti-inflammatory medications, narcotics, anxiolytics, sedatives and/or hypnotics. Concerns regarding GA stem from its association with greater costs and personnel and increased morbidity and mortality based on observational data that include analysis of cases until the mid-1980s [7], [15], [16], [17]. Therefore, GA is less frequently used in the United States [18], [19] compared to other countries, where abortions occur primarily in hospitals [20].

Nonpharmacological aspects of pain have a considerable impact on pain perception [7]. Active participation in one's own pain management and control over the life situation have been found to be beneficial [12].

Unfortunately, despite these advances, many patients still find surgical abortion extremely uncomfortable; 78–97% report at least moderate procedural pain [8], [12], [14], [21]. Therefore, optimizing pain control should be a goal in every procedure. Opinions may vary on how much pain reduction is clinically relevant. Strategies designed to reduce abortion-related pain have great public health importance considering the large numbers of women who undergo first-trimester surgical abortions.

This review will examine the existing randomized controlled trials to compare the effect of different methods of pain control during first-trimester surgical abortion on patient-perceived pain, satisfaction, side effects and safety. The review will investigate preemptive as well as intraoperative analgesia, focusing on pharmacological methods administered via mucosal (oral, vaginal, intrauterine, buccal/sublingual), intramuscular or intravenous routes, but also include nonpharmacological methods. The objective of this review is to compare the effect of different methods of pharmacological and nonpharmacological pain control administered prior to or during first-trimester surgical abortion (<14 weeks gestation with electric or manual suction aspiration) on patient perceived pain, satisfaction, side effects and safety.