Mechanosensitivity before and after hysterectomy: a prospective study on the prediction of acute and chronic postoperative pain.

BACKGROUND The incidence of chronic pain after hysterectomy is reported to be up to 30%, but the relative role of different pathogenic factors has not been defined. This study aimed to assess the predictive value of preoperative abdominal and vaginal mechanosensitivity for the subsequent development of acute and chronic pain after hysterectomy. METHODS Ninety women undergoing hysterectomy for benign conditions were studied. Experimental testing was carried out on the day before hysterectomy, on the first postoperative day, and after 4 months. Abdominal testing included brush-evoked allodynia, pinprick hyperalgesia, wind-up-like pain, and pressure pain thresholds. Vaginal testing included pressure pain thresholds. The intensity of pelvic pain was recorded on a numerical rating scale before hysterectomy, daily in the first postoperative week, and after 4 months. RESULTS The incidence of pelvic pain was 51% before hysterectomy and 17% after 4 months. Before hysterectomy, brush-evoked allodynia and pinprick hyperalgesia were more frequent in women with pelvic pain (P=0.04 and 0.02, respectively), with abdominal and vaginal pressure pain thresholds being lower in those with preoperative pelvic pain (P=0.04 and <0.01, respectively). Preoperative brush-evoked allodynia, pinprick hyperalgesia, and vaginal pressure pain threshold were associated with the intensity of acute postoperative pain (P=0.04, <0.01, and <0.01, respectively). Preoperative brush-evoked allodynia was also associated with pelvic pain after 4 months (P<0.01). CONCLUSIONS Preoperative pain sensitization as reflected by cutaneous and vaginal hypersensitivity is associated with acute pain after hysterectomy, but less so with persistent pain.