Assessment of pain threshold and pain tolerance in women in labour and in the early post-partum period by pressure algometry.

ABSTRACT

The changes in the pressure pain threshold (PPThr) and pressure pain tolerance (PPTol) in 41 parturients have been studied during the active phase of labour and in the early post-partum period. The sensitivity to pressure stimuli was examined with an electronic pressure algometer placed on the sternum during the interval between painful contractions, after extradural analgesia and 24 h after childbirth. Prior to extradural analgesia, mean (+/- SD), PPThr and PPTol were 4.9 +/- 1.6 kg 0.25 cm-2 and 6.9 +/- 1.8 kg 0.25 cm-2, respectively. Similar values were recorded 1 h after induction of the extradural block when the pain of labour was abolished. At 24 h post-delivery, a significant decrease in both PPThr and PPTol was noted (P < 0.001). The lack of influence of extradural analgesia on pressure algometry values, and the elevated sensitivity to pain in the early post-partum period, may be related to the influence of pregnancy and labour on the appreciation of pain.