The use of a paraspinal field block before epidural analgesia for labour

The purpose of this study was to determine whether paraspinal field block (PSFB) reduced the pain of epidural needle insertion and the incidence of prolonged post partum back pain in patients receiving epidural analgesia for labour. Patients were randomly assigned to receive local infiltration only with 1-1.5 ml of 1.5% lidocaine (group C, N = 27) or PSFB consisting of an additional 1 ml of 1.5% (group S, N = 30) through the midline skin wheal, on either side of the midline (total 2 ml), near the lamina, before needle insertion. Back pain was measured at the time of needle insertion, before discharge from hospital and 6 weeks post partum, by a blinded observer. There were no differences between groups in maternal or neonatal demographic data. There was no difference in back pain at any of the times measured. The incidence of severe back pain 6 weeks post partum was 0% in group C and 6.6% in group S (combined incidence group C+group S = 3.5%). The cause of post partum back pain is multifactorial and is not dependent on technique of epidural insertion. We conclude that PSFB is ineffective in reducing the pain of epidural needle insertion in labouring patients. Although this study was too small to detect a difference in incidence of late post partum back pain, it appears to be less common than previously reported.