Pain levels in visual analog scale between sham and paracervical block during the abortion procedure are illustrated in Figure 3. Baseline and speculum insertion pain did not differ between paracervical block and sham groups. Women receiving a paracervical block reported significantly less pain with both dilation (mean 42 compared with 79 mm, P<.001) and aspiration (mean 63 compared with 89 mm, P<.001) than women in the sham group but more pain with the actual administration of the paracervical block (mean 54 compared with 30 mm, P<.001). However, women receiving a paracervical block had slightly higher postoperative pain scores (mean 33 compared with 23 mm, P<.02) and requested more postoperative narcotics (Fig. 3; Table 3).
Figure 4 depicts the box plots of both dilation (Fig. 4A) and aspiration pain (Fig. 3B) between gestational age sham and paracervical block groups. Regardless of gestational age being early or late, dilation and aspiration pain scores were significantly lower in the paracervical block group. In the paracervical block group, the correlation between dilation pain and gestational age was significant (r=0.36, P=.005, data not shown). Dilation pain scores were significantly lower at early (median 32 mm, range 0–88 mm) than at late (median 57 mm, range 1–100 mm) gestational age (P=.02) (Fig. 4A), whereas aspiration pain was similar between early and late groups (Fig. 4B). In the sham group, no association was found for both dilation and aspiration with gestational age (r=0.10, P=.45, data not shown), and pain level was similar between early and late for both dilation (median 81 compared with 88 mm) and aspiration pain (median 91 compared with 93 mm).
Pain medication use in the past 60 days did not differ between groups and was not associated with dilation or aspiration pain.
Satisfaction scores, especially with pain control but also with the procedure, were significantly higher in paracervical block group (Fig. 5). Of note, the majority of women were able to identify to which group they had been randomized (sham 69% and paracervical block 70%).
This randomized trial demonstrated that paracervical block is effective in decreasing patient-reported pain at various steps throughout an induced abortion procedure. Although paracervical block administration was painful, it significantly decreased cervical dilation and uterine aspiration pain. Although paracervical block decreased pain regardless of gestational age, its effect on dilation pain appeared to wane with increasing gestational age.
The strengths of the present study include its randomized single-blind controlled design with a separate randomization for early and late gestational age to ensure a representative distribution. We used a sham comparison arm in the absence of any confounders such as conscious sedation or cervical ripening. We encountered minimal dropout and intention-to-treat practices were used.
The generalizability of our data is limited because we only included women with a gestational age less than 11 weeks. This limit was purposefully chosen to reduce confounding because standard clinical protocols at our study site require cervical ripening with misoprostol after 10 6/7 weeks of gestational age. Because the benefits of paracervical block appear to decrease with increasing gestational age, further study is necessary to see if paracervical block use should be recommended above 11 weeks of gestation or in the presence of misoprostol for cervical ripening.
Unfortunately, most women in the study were able to identify the treatment group to which they were randomized, which may have introduced reporting bias. We believe this occurred from the very detailed description of the study procedures required of us to include in the written consent. Nonetheless, women still reported that paracervical block administration hurt and our effect size far exceeded what one would expect if only a “placebo” effect was being reported for the paracervical block.23,24 A mean pain reduction of 13 mm or more measured on a 100-mm visual analog scale has been considered clinically meaningful20 – 22; the effect size observed in our results was 20–30 mm.
Paracervical block is thought to provide pain control for cervical dilation through the parasympathetic fibers of S2 to S4 innervating cervix and lower uterine segment. Because the block does not reach the sympathetic fibers from T10 to L1 innervating the uterine fundus,8 the mechanism of aspiration pain may not be explained by this anatomic distribution of nerves unless one assumes that the 3-minute wait allowed for the anesthetic to disseminate upward. However, this hypothesis is in conflict with the increased postoperative pain and request for more postoperative analgesics in the paracervical block group. Pain relief from lidocaine should persist for 1.5–2 hours; if greater distribution of the analgesic occurred, we would have expected the opposite in these women. However, even with the increase in postoperative pain, satisfaction was significantly higher in the paracervical block group. Our original hypothesis was that increasing pain occurs with increasing gestational age as a result of the increased need for dilation. The existing literature is conflicting whether earlier or later gestational age experiences more pain with observational data suggesting no correlation or increased pain at earlier gestational age. We found that dilation pain significantly increased with gestational age but only in the paracervical block group. Interestingly, this correlation was not present in our sham group, which may be the result of the overall increase in procedure-related pain for this group blunting the small gestational age-associated differences.
Not surprisingly, procedure-related pain was negatively correlated with pain-related and procedure-related satisfaction (data not shown). Satisfaction was significantly lower in the sham group, indicating that women find a painful paracervical block injection more acceptable than the pain experienced with the abortion procedure. However, overall satisfaction rates were high regardless of pain control, which highlights that analgesia is only one aspect of the abortion experience.
To ensure that our study would have the greatest chance of demonstrating an effect, we purposefully selected a rigorous paracervical block technique that requires more needle sticks (four rather than two), more local anesthetic (20 mL rather than 10 mL), and a longer wait time (3 minutes compared with no wait) than the technique used by most clinicians. Therefore, our results should not be considered generalizable to other paracervical block techniques. In fact, our technique likely resulted in the observed difference from studies that have not demonstrated a positive effect.4 However, our results do not allow us to infer whether the anesthetic effect of a paracervical block is principally related to distribution (eg, number of needle sticks, volume), dose (eg, total drug delivery, concentration, drug pharmacokinetics), or set-up time (eg, delay between injection and procedure) of a local anesthetic.
In conclusion, our sham paracervical block controlled randomized controlled trial supports a benefit of the widely used paracervical block for induced first-trimester surgical abortion regardless of gestational age. Future research should focus on refinement of the paracervical block technique.
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© 2012 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.
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