['Accidental cannulation of an epidural vein is a common complication associated with epidural anesthesia or analgesia. On the basis of a pilot study and previous reports, we tested the hypothesis that predistention of the epidural space with saline before epidural catheterization would ease catheter insertion and decrease the incidence of this complication.', 'Two-hundred-three laboring women were randomly assigned to receive an epidural with loss of resistance technique with 2 mL (nondistention) or 5 mL saline (distention). In the distention group, the syringe plunger was held closed before epidural catheter insertion. Then in both groups, a test dose of 3 mL of 1.5% lidocaine was injected through the epidural catheter.', 'There were fewer accidental intravascular catheter placements (2% vs 16%, P = 0.0001) in the distention group, and 91% of patients in this group did not have any unblocked segments versus 67% in the nondistension group (P = 0.0001). The difference in onset time of analgesia was small (5.0 +/- 2 min vs 6 +/- 3 min, P = 0.0001) and not clinically important. The quality of analgesia (visual analog scores and ropivacaine consumption) was similar between groups.'] Does predistention of the epidural space before catheter insertion reduce the incidence of intravascular epidural catheter insertion?