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Clinical Trial Summary

More research is needed to investigate methods of pain control for cervical preparation for abortion procedures. Women report pain with paracervical block injection as well as with osmotic dilator placement. This study seeks to compare a 12 mL, 2-site 1% plain lidocaine paracervical block for pain control during cervical preparation (osmotic dilator insertion) for Dilation and Evacuation (D&E) to a 20 mL 1% lidocaine 2-site paracervical block.

Clinical Trial Description

Paracervical block (PCB) is a widely used, but largely unstandardized technique for pain management in gynecological procedures. From hysteroscopy to first trimester abortion procedures to dilator placement for dilation and evacuation, providers utilize the paracervical block to manage cervical dilation pain. However for such a widely used technique, the exact method is often provider or site specific. A 2009 survey of National Abortion Federation members illustrates that the volume alone of anesthestic used for PCB in first trimester abortion procedures varies tremendously amongst providers. That said, research published over the last few years has had enormous impact on global guidelines, such as those published by Ipas. New techniques for paracervical block that focus on limiting symptoms and resources while also ensuring adequate pain management are needed to improve care for women around the world.

A randomized controlled trial done by Renner et al. in 2012 demonstrated that a 4-site, 18 mL 1% lidocaine paracervical block, with a 2 mL injection for tenaculum placement, used during first-trimester surgical abortions was beneficial in reducing pain due to cervical dilation when compared to sham paracervical block. The block technique endorsed by Renner et al. was based on findings from a combination of studies about paracervical block that investigated variations in needle injection site , type of lidocaine , depth of lidocaine injection , general vs. local anesthesia , and wait time between injection and procedure . Missing from consideration, however, was the volume of lidocaine necessary to achieve a reduction in dilation pain. The final technique used in Renner et al.'s study was as follows:

- Syringe loaded with 18 mL of 1% plain lidocaine buffered with 2 mL 8.4% sodium bicarbonate (20 mL total); 20-gauge spinal needle

- 2 mL injected at the tenaculum site, 12 o'clock superficially into the cervix

- The tenaculum is immediately placed at 12 o'clock

- The remaining 18 mL are injected slowly over 60 seconds into the cervicovaginal junction in four equal aliquots at 2, 4, 8, and 10 o'clock; the injection is continuous from superficial to deep (3 cm) to superficial (injecting with insertion and withdrawal)

- Dilation begins 3 minutes after application of the block

A subsequent study done by Renner et al. in 2016 aimed to further refine this technique and looked at both the 3-minute wait time and the use of 4-site versus 2-site injection. Results of the study were largely inconclusive, suggesting that no wait time is no worse than a three-minute wait and that 2-site and 4-site injections may be interchangeable. Despite these findings, global guidelines and provider preference continue to follow findings from Renner et al.'s 2012 study.

As the dangers of lidocaine injection are minimal, but not absent, and the administration of a paracervical block is painful and time-consuming, this study will compare a technique similar to the one put forth by Renner et al. with one that has been used in multiple Stanford studies and notably employs a smaller volume of lidocaine and only two injection sites. The technique is as follows:

- Syringe loaded with 12 mL of 1% lidocaine (120 mg); 22-gauge spinal needle

- 2 mL injected at the tenaculum site, either 6 or 12 o'clock superficially into the cervix

- The tenaculum is immediately placed at the previously injected site

- The remaining 10 mL are slowly injected into the cervicovaginal junction in two equal aliquots at 4 and 8 o'clock; the injection is continuous from superficial to deep (3 cm) to superficial (injecting with insertion and withdrawal)

- No wait time between injection and dilator insertion

This will be compared with a technique similar to Renner et al.'s technique from 2016:

- Syringe loaded with 20 mL of 1% lidocaine (120 mg); 22-gauge spinal needle

- 2 mL injected at the tenaculum site, either 6 or 12 o'clock superficially into the cervix

- The tenaculum is immediately placed at the previously injected site

- The remaining 18 mL are slowly injected into the cervicovaginal junction in two equal aliquots at 4 and 8 o'clock; the injection is continuous from superficial to deep (3 cm) to superficial (injecting with insertion and withdrawal)

- No wait time between injection and dilator insertion

The justification for this proposed technique comparison is as follows:

With regards to smaller dosage, there is much research to be done. While the lidocaine label recommends a maximum dose of 200 mg (20 mL at 1%) of lidocaine per 90-minute period for paracervical block, it does not recommend a minimum dose. Renner et al.'s 2012 study provides evidence for paracervical block over sham for cervical dilation pain and Chanrachakul's 2001 study provides evidence that pain relief comes from both lidocaine and distention rather than distention alone. These studies point to the benefit of using lidocaine, but to date there is little data providing the optimal dose between 0 mL and 20 mL. With this knowledge, this study proposes the use of 10 mL of lidocaine in order to maintain the use of lidocaine for pain control, but minimize symptoms (such as metallic taste, ringing in the ears, and at worst, seizure or cardiac arrest) that are more likely to manifest with 20 mL.

With regards to 2-site versus 4-site, the aim is to build on the findings from Glantz and Shomento's 2001 study and Renner et al.'s 2016 study. Glantz and Shomento's study from 2001 contained four study arms and looked at both 1% chloroprocaine versus placebo and 4-site versus 2-site injection. While the original paper concluded that PCB with chloroprocaine provides more pain relief than saline for both 4-site and 2-site injections, subsequent reanalysis from 2009 showcased that preference for 4-site or 2-site versus saline depended on the time point at which pain was measured. Regardless, more importantly, the findings showed that when comparing 4-site 1% chloroprocaine block to 2-site 1% chloroprocaine block, there is no statistical difference. Furthermore, Renner et al.'s 2016 study, which compared 20 mL of 1% buffered lidocaine at 4-site versus 2-site, showcased that using noninferiority analysis, there is no statistical difference between 4-site and 2-site block. Additionally, while superiority analysis demonstrated that 4-site is statistically superior to 2-site for pain control at cervical dilation, this demonstrated difference is not clinically significant. All in all, these data point toward the clinical conclusion that 2-site may be utilized in place of 4-site. The proposed technique follows findings from these studies and if proven effective, would result in fewer painful injections during paracervical block.

Concerning depth of injection, the study will utilize the 3 cm depth as used in Renner's studies. Wiebe et al.'s 1992 study and Cetin and Cetin's 1997 study suggest utilizing deep injection, as dilation pain scores were lower for deep injection in both studies.

Phair et al.'s 2002 study and Renner et al.'s 2016 study both showcased that there is no significant difference in pain with cervical dilation when comparing no-wait between PCB injection and cervical dilation to wait. As such, the study will exclude a wait time.

With regard to plain lidocaine versus buffered lidocaine, while several studies have showcased the benefit of utilizing buffered lidocaine instead of plain lidocaine, given the high cost and prolonged preparation time associated with creation of a buffered lidocaine solution, the study will use 1% plain lidocaine. The hope is that by showcasing pain control with a more cost-effective anesthetic, the results will be generalizable to a larger global audience.

Finally, while many studies focus on pain control in first-trimester abortion, including Renner et al., in order to isolate cervical dilation pain from uterine pain, this study will focus on the cervical preparation procedure needed prior to a second trimester surgical abortion rather than the surgical procedure itself. Need for additional research in this timeframe was highlighted in Soon et al.'s work, which demonstrated that the paracervical block technique utilized by Renner et al. was effective in reducing pain associated with osmotic dilator insertion prior to second trimester abortion. Isolating the pain of the cervical dilation procedure will allow the findings to be meaningful for any procedure in which cervical dilation is necessary. ;

Study Design

Related Conditions & MeSH terms

NCT number NCT03356145
Study type Interventional
Source Stanford University
Status Enrolling by invitation
Phase N/A
Start date January 1, 2017
Completion date November 29, 2019

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