Epidural catheter migration during labour: an hypothesis for inadequate analgesia.

The purpose of this study was to determine the incidence and factors associated with poor analgesia during epidural block for labour pain. Emphasis was placed on determining the incidence, magnitude and factors associated with epidural catheter migration as well as any relationship between catheter migration and the quality of analgesia. Catheter movement was assessed, prospectively, in 211 consecutive parturients who had an epidural catheter placed for labour analgesia. The magnitude and direction of catheter movement was assessed by measurement of the length of the catheter at the skin at the time of epidural placement, and immediately before removal of the catheter, after delivery. Fifty-four per cent of the catheters migrated during labour and 70 per cent of these migrated out of the epidural space. The quality of analgesia provided by the epidural block was assessed by the caseroom nurse caring for the patient. Seventeen per cent of the patients had unsatisfactory analgesia. There was an increase in poor analgesia in those patients whose catheters migrated compared with those in whom the catheters were stable (P less than 0.05). We conclude that catheter migration during labour results in a greater incidence of inadequate block and unsatisfactory analgesia.