The Effect of Pregnancy on Temporal Summation and Venipuncture Pain Perception

Recent epidemiologic studies have shown that women are at substantially greater risk for many clinical pain conditions, and there is a suggestion that postoperative and procedural pain may be more severe among women then men. During pregnancy, women experience an elevation in the threshold to pain and discomfort. In addition to hormonal changes, the changes in pain perception during pregnancy may be related to an increase in endogenous opioids.

Pain is the most feared experience in the intra and postpartum period, and severe pain experienced during this time can lead to significant morbidity, including chronic pain and depression. Much attention has been paid to tests that can predict patients at higher risk for pain. Temporal summation (TS) has been shown to be a simple and reliable test. Temporal summation represents the physiological wind-up phenomenon taking place at the spinal level of the central pain pathways. TS extent can be measured in humans by administering a series of noxious stimuli of constant intensity and of various modalities in order to evoke an increase in perceived pain. It is a very simple and easy test to perform, and very well tolerated by patients. Whether TS changes in pregnancy and whether TS in pregnancy correlates with pain perception during acute stimuli such as venipuncture is unknown.