Background: Little information is available on time course of wound tenderness and relationship to subjective pain ratings following surgery. Furthermore, it is not clarified whether surgical procedures may induce hyperalgesia to mechanical stimulation outside the area of the surgical incision. We have therefore assessed postoperative pain and pressure pain thresholds (PPT) adjacent to and remote from the surgical incision in 16 patients undergoing hysterectomy.
Methods: Pressure pain threshold was assessed with pressure algometry preoperatively, 4 and 6 and 1, 4 and 8 d after surgery on the abdominal wall 0.05, 5, 10 and 15 cm perpendicular to the wound, and on the anterior surface of the left thigh and tuberositas tibia. Furthermore, pain was assessed on a visual analogue scale (VAS) at rest and during cough.
Results: PPT decreased significantly 0.5, 5, 10 and 15 cm from skin incision up to 96 h after surgery (P < 0.01) with a trend towards higher PPT with increasing distance from the wound. There was no significant changes in PPT on the thigh or the tuberositas tibia (P = 0.49 and P = 0.12) and no correlation between changes in PPT near the wound and in remote (areas the legs) (Rs = -0.082, P = 0.53, respectively). VAS at rest increased from 4 to 24 h and the cough values, remained elevated throughout the study (P < 0.05). An inverse relationship was observed between PPT 5 cm from the incision and VAS at rest (Rs = -0.406, P = 0.0002) and during cough (Rs = -0.398, P = 0.0002).
Conclusion: These results indicate that wound pressure algometry correlates to postoperative pain at rest and during movement and may be an alternative way of assessing wound pain and tenderness. Increased tenderness to mechanical stimulation remote from the surgical wound could not be demonstrated.