Refining paracervical block techniques for pain control in first trimester surgical abortion: a randomized controlled noninferiority trial

Objectives Our objective was to evaluate two different aspects of the paracervical block (PCB) technique for first trimester surgical abortion, to compare a 3-min wait prior to cervical dilation to no wait and to compare four-site with two-site injection. Study design We conducted two consecutive randomized, single-blinded noninferiority trials. In the first trial, women < 11 weeks gestational age received a 20-mL 1% buffered lidocaine four-site PCB with either a 3-min wait between PCB injection and dilation or no wait. In the second trial, we compared a four-site with a two-site PCB. We evaluated dilation pain [100-mm visual analogue scale (VAS)] as the primary outcome. Secondary outcomes included pain at additional time points, anxiety, satisfaction and adverse events. Results Both trials fully enrolled (total n = 332). Results were inconclusive as to whether no wait was noninferior to waiting 3-min prior to cervical dilation for dilation pain [VAS: 63 mm (SD, 24 mm) vs. 56 mm (SD, 32 mm)] and as to whether a two-site PCB was noninferior to a four-site block [VAS: 68 mm (SD, 21 mm) vs. 60 mm (SD, 30 mm)]. Noninferiority analysis was inconclusive because the confidence interval of the mean pain score difference between groups included the predefined inferiority margin of 13-mm pain difference. Superiority analysis showed the four-site PCB to be superior to the two-site PCB. Conclusion It remained inconclusive whether a 3-min wait time between PCB and cervical dilation provides noninferior pain control for first trimester surgical abortion. However, a four-site PCB appeared to be superior to a two-site PCB. Implications It remained inconclusive whether a 3-min wait time between PCB and cervical dilation or using a two-site instead of a four-site PCB provided noninferior pain control for first trimester surgical abortion. This study did not assess whether the combination of the two separate factors provides additive benefit.