Quantification of abdominal wall pain using pain pressure threshold algometry in patients with chronic pelvic pain.

OBJECTIVE: Chronic pelvic pain (CPP) is a syndrome involving 1 or more pain generating organs in the pelvis, which includes pain from the lower anterior abdominal wall. This entity has been termed myofascial pain syndrome (MFPS), but its characteristics, definition, and quantification have not been well described. In this study, pain pressure threshold (PPT) testing of the lower anterior abdominal wall in CPP patients was performed to determine the range and distribution of values at each site, and the clinical utility of using PPT in a definition of MFPS.
METHODS: Fifty-six patients evaluated in a CPP specialty clinic underwent PPT algometry of 14 sites on the lower anterior abdominal wall. These values were described and evaluated before and after treatment. PPT values were also evaluated in patients found to be drug seeking.
RESULTS: Twenty percent of the PPT tests reached the threshold of 3 kgf/cm2. The abnormal tests usually formed a normal distribution. PPT testing had a weak but appropriate correlation with other pain symptom measures. After trigger point injection there was a 75% improvement in PPT, and response to medical therapy resulted in a 60% improvement. A composite measure was able to distinguish drug-seeking patients with statistical accuracy. DISCUSSION: PPT testing can be used to evaluate MFPS in CPP patients. One suggested definition would exclude patients with low scores in the upper abdomen while including patients with low scores in the lower abdomen.