Posture and the spread of extradural analgesia in labour.

Thirty-five patients kept in a sitting position for 5 min after a standard extradural injection in labour were compared with 54 patients maintained in the left lateral position throughout. The mean upper limit of analgesia was unchanged. A significant shift of the mean lower limit occurred in the sitting patients (P = 0.05, two-tailed), but contrary to classical teaching this was in a cephalad direction. Successful sacral blockade (analgesia at S234) and asymmetry of blockade occurred in a similar proportion of each group. It was concluded that the sitting position conferred no clinical advantage to patients receiving extradural analgesia in labour.