**9. Relationship to pelvic floor**

In a study of 112 women with chronic pelvic pain assessed for pain in the abdominal wall, perineum, levator ani, and obturator internus, the number of myofascial trigger points was predicted by the number of previous laparoscopies adjusted for age. Both the presence of visceral disease and endometriosis were significantly associated with higher numbers of myofascial dysfunction than the absence of these conditions [17]. These findings suggested that prior surgery may aggravate pain sensitization. The available studies using pain testing do not indicate they can discriminate endometriosis from other visceral diseases [3, 13, 18]. It should also be noted here the test for allodynia on the perineum was validated as noted above [13].

### **10. Possible future benefits of pain testing**

It has long been known that the extent of disease does not have a correlation with the severity of pain. Many women with minimal disease are severely incapacitated with their pain. Alternatively, but less common, are women with severe stage 4 disease without pelvic pain. Many gynecologists have seen women who have had repeated procedures for minimal disease despite having no change in their pain [18]. The techniques of pain testing can provide an assessment indicating peripheral and central sensitization have altered pain physiology and possibly eliminate the need for repetitive laparoscopic surgery of limited, if any, benefit.

There have been several blinded controlled trials of the excision versus sham excision of endometriosis for the management of pain [19–22]. The results have differed; in several, there was a reduction in pain; in another that was extended out 14 years post-randomization, there was no difference between the sham excision and excision. Perhaps it may not be the surgeons' expertise, the degree of disease, or prior pelvic surgery, but the differences may possibly be explained by the womens' pain sensitization. Pain testing might have a unifying feature to allow comparisons of cohorts of subjects in clinical trials.

Many surgeons have had the unsettling experience of having one of their women undergo what is considered a straightforward operation of hysterectomy, tubal ligation, or laparoscopic excision of endometriosis in which the woman returns with severe incapacitating pelvic pain. The reason is not in the operative procedure that was uncomplicated, but it is difficult at times to persuade that to the woman involved. Possibly, there was a preexisting state that made this possible. In reviewing women presenting with postoperative onset of chronic pelvic pain, there is commonly a history of pain preceding the operation. This can take the form of severe dysmenorrhea, repetitive bouts of cystitis, or prior kidney stones. Pain causes chronic pain and while it is possible to generate chronic pelvic pain from an isolated procedure, it is much more common to see there was a previous pattern of repetitive pain. The shift to a chronic pain state might be identified as a risk with pain testing for sensitization.

#### *Endometriosis*

Also, there is a troubling experience of undertaking an operative laparoscopy anticipating there is going to be endometriosis present and instead finding no disease whatsoever. Again, this leads to difficult explanations and often the patient will seek yet another laparoscopy.

These examples are fundamentally issues of pain and pain management. In order to have a strategy to inform these situations, pain testing might be of assistance.
