Women with Chronic Pelvic Pain Are More Sensitive to All Pain
Abstract & Commentary
By Jeffrey T. Jensen, MD, MPH, Editor
Synopsis: Compared to normal women and women with endometriosis without chronic pain, women with chronic pelvic pain demonstrate increased pain sensitivity at nonpelvic sites.
Source: As-Sanie S, et al. Increased pressure pain sensitivity in women with chronic pelvic pain. Obstet Gynecol 2013;122:1047-1055.
The relationship between chronic pelvic pain and endometriosis is complex. Many chronic pain conditions are associated with a generalized increased sensitivity to pain. To determine whether this is true in chronic pelvic pain, the authors compared the response to pain between healthy control women and women with various presentations of chronic pelvic pain and endometriosis. Women with prior surgical evaluation of chronic pelvic pain or endometriosis were recruited. The evaluation groups included 1) endometriosis with chronic pelvic pain, 2) endometriosis with dysmenorrhea only, 3) pain-free endometriosis, and 4) chronic pelvic pain without endometriosis. The control group consisted of healthy women without a history of pelvic pain or endometriosis. All subjects underwent a standardized evaluation, completed validated questionnaires regarding pain symptoms, and were screened for comorbid pain disorders. Pain sensitivity was assessed by applying discrete pressure stimuli to the thumbnail using a technique previously validated by the authors that delivers a series of increasingly intense pressure stimuli to the non-dominant thumbnail. To minimize the influence of cycle-related pain on study results, all study visits were performed between days 2 and 10 of the menstrual cycle in women who were not using hormonal contraceptives. Subjects were asked to refrain from using opioid analgesia within 48 hours of the study visit.
Compared to healthy controls, all subgroups of women with chronic pelvic pain demonstrated a significantly lower pain threshold. In contrast, women with endometriosis without pelvic pain reported a pain threshold that was no different than women in the control group. Furthermore, the severity of endometriosis and number of comorbid pain syndromes were not associated with a difference in pain thresholds. The finding of increased pain sensitivity at a nonpelvic site in women with chronic pelvic pain that is independent of the presence or severity of endometriosis or comorbid pain syndromes supports the notion that central pain amplification may play a role in the development of pelvic pain. This may explain why some women with pelvic pain do not respond to therapies aimed at eliminating endometriosis lesions.
The management of chronic pelvic pain is confusing and frequently not rewarding for the clinician. Unfortunately, many experts emphasize the importance of establishing or excluding a diagnosis of endometriosis prior to beginning therapy. This typically requires a surgical adventure. While the risks associated with laparoscopy are low, they are not zero and the procedure and diagnosis of endometriosis offers little benefit to most women. The cross-sectional Endo Study found the incidence of endometriosis diagnosed at surgery to be 40% in a group of women having procedures for a variety of indications. However, most cases are minimal or mild in severity. Only 12% had advanced (ASRM stage 3-4) disease, and this was no different from that seen when MRI was used to screen asymptomatic community-based controls.1 So if you look for endometriosis, there is a good chance you will find it in patients with and without pelvic pain. Since the mainstay treatments for endometriosis are hormonal and can be applied without a surgical diagnosis, there should be another reason to consider surgery. The presence of a fixed pelvic mass may indicate surgery, but not a suspicion of endometriosis, as the surgical management will not change treatment or prognosis.
Women with chronic pelvic pain require a thoughtful nonsurgical evaluation. The study from As-Sanie et al provides further insight into the complex nature of chronic pelvic pain and provides greater separation from endometriosis. Women in this study were carefully selected and categorized according to the presence of pain, and the presence or absence of endometriosis seen at surgery. The key conclusion was that women with chronic pelvic pain with or without endometriosis are more pain sensitive at nonpelvic sites than healthy women. In contrast, women with endometriosis without pain had the same pain threshold as healthy women. While these findings are not surprising, they reinforce the decision to manage chronic pelvic pain as a complex medical and not surgical problem.
An elegant randomized study conducted more than 20 years ago in the Netherlands tested this approach.2 In the standard-approach group, diagnostic laparoscopy was routinely performed to exclude organic causes of chronic pelvic pain. If no somatic cause could be found, attention was given to other causes such as musculoskeletal and psychological disturbances. In the second group, laparoscopy was not routinely performed, and an integrated approach that devoted equal attention to somatic, psychological, dietary, environmental, and physiotherapeutic factors was used. Both groups were similar with respect to baseline clinical characteristics; postcoital pain was reported by 27% and 20% who had experienced negative sexual experiences such as childhood sexual abuse or rape. After one year of therapy, it was found that the integrated approach improved pelvic pain significantly more often than the standard approach. Only 10% of women in the integrated approach group underwent laparoscopy, and laparoscopy played no important role in the treatment of pelvic pain in either group. The authors concluded that equal attention to both organic and other causative factors from the beginning of therapy was more likely to result in a reduction of pelvic pain than is a standard approach. A multidisciplinary approach that includes physical therapists, counselors, and pain specialists will help most women. Providing women with this new information about pain perception may help some to understand the complexity of the process, and move forward with a multidisciplinary approach.
- Buck Louis GM, et al. Fertil Steril 2011;96:360-365.
- Peters AA, et al. Obstet Gynecol 1991;77:740-744.