Paracervical Block for Pain Control
Abstract & Commentary
By Jeffrey T. Jensen, MD, MPH , Leon Speroff, Professor and Vice Chair for Research, Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, is Editor for OB/GYN Clinical Alert.
Synopsis: In a randomized, placebo-controlled study, a paracervical block was shown to be effective in reducing pain with cervical dilation and with uterine aspiration during first trimester abortion.
Source: Renner RM, et al. Paracervical block for pain control in first-trimester surgical abortion: A randomized controlled trial. Obstet Gynecol2012;119:1030-1037.
The authors performed a randomized, single-blind trial of the effects of a paracervical block (PCB) or sham block on pain with cervical dilation and aspiration during first trimester abortion. Enrollment of subjects was stratified by gestational age (early: < 8 weeks, n = 60; late: 8-10 6/7 weeks, n = 60). All subjects received premedication with ibuprofen and lorazepam, and 2 mL 1% buffered lidocaine injected at the tenaculum site prior to tenaculum placement. This was followed by a slow, deep injection of 18 mL of buffered lidocaine at four sites (2, 4, 8, 10 o'clock [block group]) or a sham injection (no needle) followed by a 3-minute wait. The primary outcome was dilation pain (measured on a 100-mm visual analog scale). Secondary outcomes included pain at additional time points, satisfaction with the procedure, need for more analgesics, and adverse events. Although subjects assessed the paracervical block administration as painful (block mean 55 mm compared with sham 30 mm P < 0.001), the block decreased both dilation pain (42 mm compared with 79 mm, P < 0.001) and aspiration pain (63 mm compared with 89 mm, P < 0.001). Although these results were consistent for both gestational age strata, the benefit was greatest in the early gestational age group. Satisfaction scores with pain control and the procedure also were significantly higher in the block group.
Commentary
I typically don't like to highlight one of our own studies, but this is an important one. I suspect that most of you regularly use a PCB for a variety of office procedures. For something we do so frequently, it is surprising that there is so little evidence to support the use of the PCB. The many small variations in technique suggest that we may be comparing apples to oranges. In fact, many well-designed studies have come to opposite conclusions regarding the effectiveness of the block in reducing dilation pain.1 Furthermore, we know that the block can hurt.
In our clinic, we began to selectively avoid PCB during very early gestational age uterine aspiration, reasoning that the benefit did not outweigh the discomfort of the block. Sometimes our clinical judgment can lead us in entirely the wrong direction. Dr. Renner reviewed the literature on PCB and pain control in first trimester abortion, and decided to test this hypothesis. Her Cochrane review details the state of the art.1
To determine whether the PCB works, Renner reviewed the literature to combine all features of the block that might contribute to success: buffered lidocaine to reduce injection pain, a four-injection technique to create a larger field, a larger volume (20 mL) of anesthetic, and a wait time (3 minutes) following injection to allow the block to set. Although I suspect that all of us incorporate some of these steps in our own block, this was truly a gold-standard technique. But from a practical perspective, it is tough to administer multiple injections and wait for 3 minutes during a busy clinic session. During the study, the investigators were secretly hoping that the block would not work so we could stop using it!
The results were surprising and powerful. Although subjects identified the block as painful, there was a powerful reduction in pain with dilation and with uterine aspiration. The later finding was particularly unexpected, as most of us believe that the benefit of the PCB is at the cervix only. Moreover, subjects who received the block were more satisfied with their pain control despite the pain of administration.
Renner created a gold-standard block, so we still have more work to do to dissect this down to components. Is it the wait time, volume, multiple sites, or the combination? Although it is tempting to apply the results of this study to your personal PCB technique, I believe that the burden of evidence would suggest that you need to apply the 20 mL, four-site injection technique with a 3-minute wait to have the best results.
I think this really works and have now applied it to other office procedures where cervical dilation or uterine anesthesia might be helpful. This might be effective for IUD insertions, Essure procedures, etc. We will need to do the studies to find out for sure.
Reference
- Renner RM, et al. Pain control in first trimester surgical abortion. Cochrane Database System Rev 2009:Issue 2: CD006712.
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