Suprasensitivity to calcitonin gene-related peptide but not vasoactive intestinal peptide in women with chronic pelvic pain.

Chronic pelvic pain in women is associated with radiological evidence of pelvic venous dilatation and reduced flow, termed 'pelvic congestion'. The aim of this study was to elucidate a possible role in this condition for vasoactive intestinal peptide and calcitonin gene-related peptide, both localized in perivascular nerves in the ovaries and uterus. Healthy volunteers and women with chronic pelvic pain and venous congestion received intravenous infusions of vasoactive intestinal peptide (n = 15), calcitonin gene-related peptide (n = 15) or a bland infusate (n = 7). Changes in the uterovaginal and skin blood flow were assessed by continuous measurement of vaginal, axillary, cheek and hand temperature. During calcitonin gene-related peptide infusion median hand temperature changes were +0.97 degrees C in women with pelvic pain and -0.03 degrees C in healthy volunteers (p < 0.05). There were no differences between groups in hand and cheek temperature responses to vasoactive intestinal peptide infusion. Vasoactive intestinal peptide and calcitonin gene-related peptide appeared to dilate the uterovaginal vasculature in healthy subjects but not in those with pelvic pain. Vasoactive intestinal peptide and calcitonin gene-related peptide did not provoke pain in healthy subjects but in those with pelvic pain, symptoms were significantly exacerbated during calcitonin gene-related peptide infusion but not by vasoactive intestinal peptide. Changes in plasma follicle stimulating hormone, luteinizing hormone and oestradiol during either infusion were not significant. These findings indicate greater sensitivity to calcitonin gene-related peptide in women with pelvic pain and suggest a possible underlying neurovascular disorder.