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A Comparison of Paracervical Block Volumes Before Osmotic Dilator Placement: A Randomized Controlled Trial
Kate A Shaw1, Klaira Lerma, Tayler Hughes
1Family Planning Services and Research, Department of Obstetrics and Gynecology, Stanford School of Medicine, Stanford, California.
Obstetrics and Gynecology
|August 5, 2021
Summary
A 12-mL paracervical block effectively reduces pain during osmotic dilator insertion, matching the efficacy of a 20-mL block. This finding supports using a smaller volume for pain management in second-trimester abortions.
Area of Science:
- Obstetrics and Gynecology
- Pain Management
- Pharmacology
Background:
- Second-trimester abortions often involve osmotic dilator insertion, a procedure that can cause significant pain.
- Paracervical blocks using lidocaine are commonly employed to manage procedural pain.
- The optimal volume of lidocaine for paracervical blocks in this context requires further investigation.
Purpose of the Study:
- To determine if a 12-mL paracervical block is noninferior to a 20-mL block in alleviating pain during osmotic dilator insertion.
- To compare the efficacy and safety of two different volumes of lidocaine for paracervical blocks.
Main Methods:
- A single-blinded, noninferiority trial randomized 96 participants undergoing osmotic dilator insertion to receive either a 12-mL or 20-mL 1% lidocaine paracervical block.
- The primary outcome was pain intensity immediately after osmotic dilator insertion, measured on a 100-mm visual analog scale.
- Secondary outcomes included pain during block administration, overall pain, and adverse events. Statistical analysis involved Wilcoxon rank sum, chi-squared, and t-tests, with ANOVA for repeated measures.
Main Results:
- The 12-mL paracervical block was found to be noninferior to the 20-mL block for pain reduction during osmotic dilator insertion (mean difference -1.36 mm; 95% CI -12.56 to 9.85).
- Median pain scores post-insertion were similar between groups (47 mm for 12-mL vs. 50 mm for 20-mL; P=.81).
- Lidocaine-related side effects occurred less frequently in the 12-mL group (4%) compared to the 20-mL group (13%), though this difference was not statistically significant (P=.15).
Conclusions:
- A 12-mL paracervical block provides equivalent pain relief to a 20-mL block during osmotic dilator insertion.
- The findings suggest that a reduced volume of lidocaine may be sufficient for effective pain management, potentially minimizing side effects.
