Pelvic floor, abdominal and uterine tenderness in relation to pressure pain sensitivity among women with endometriosis and chronic pelvic pain

Abstract

Objective: Pelvic floor pain, abdominal wall pain, and central nervous system pain amplification can be contributing factors in chronic pelvic pain (CPP), however; limited research has investigated the association of pelvic floor, abdominal, and uterine tenderness with central nervous system pain amplification. We assessed whether pressure pain thresholds on the non-dominant thumbnail, a marker of central nervous system pain amplification, were associated with pelvic floor, abdominal, and uterine tenderness among women with endometriosis or CPP.

Study design: We conducted a cross-sectional study among 88 females with endometriosis and/or CPP. Abdominal (6 locations), pelvic floor (6 locations) and uterine (1 location) tenderness were assessed via a standardized physical exam. Participants reported their pain levels (0-10 scale) with application of 2 kg of pressure at each area, with a pain rating of ≥4 on the 0-10 scale considered moderate to severe pain. Pain sensitivity was measured on the non-dominant thumbnail by applying discrete pressure stimuli using a previously validated protocol.

Results: Overall, 50% (44/88), 42% (37/88), and 58% (51/88) of participants reported high pelvic floor, abdominal, and uterine tenderness, respectively. Pressure intensities needed to elicit 'faint' and 'mild' pain were lower for participants with high vs. low pelvic floor tenderness (median intensity for 'faint' pain = 0.50 kgf/cm2(min-max:0.25-3.25) vs. 1.06(0.25-3.00), p-value = 0.006; median intensity for 'mild' pain = 2.00(0.63-4.88) vs. 2.63(0.75-6.00), p-value = 0.03). No association was observed between pressure pain sensitivity and abdominal or uterine tenderness (p > 0.11). Participants with endometriosis without pain were less likely to have high pelvic floor (22.2%), abdominal (11.1%), and uterine (25.9%) tenderness compared to participants with endometriosis with pain (63.0%, 50%, 65.2%, respectively) and participants with chronic pelvic pain (60%, 73.3%, 93.3%, respectively).

Conclusions: These results suggest that high pelvic floor tenderness among women with endometriosis/CPP may be a marker of heightened pain sensitivity suggestive of central nervous system pain amplification and may impact treatment response. Future research should examine whether this clinical phenotype predicts response to medical and behavioral treatments (e.g, anti-convulsants, behavioral therapy, Physical Therapy).

Keywords: Chronic pelvic pain; Endometriosis; Generalized nociceptive hypersensitivity; Nociplastic pain; Pressure pain sensitivity; Quantitative sensory testing.

Conflict of interest statement

Declaration of Competing Interest S.A. has served as a consultant for Abbvie, Bayer, Myovant Sciences and Merck, and receives royalties as an author for UpToDate. D.J.C. has served as a consultant for Pfizer, Lilly, Tonix, Aptinyx, Samumed, Zynerba, and has received research funding from Aptinyx. S.E.H. has served as a consultant for Aptinyx, and has received research funding from Arbor Medical Innovations and Aptinyx. S.A.M. has served as an advisory board member for Abbvie and Roche. A.L.S., E.M., and C.B.S. report no conflict of interest.

Copyright © 2021 Elsevier B.V. All rights reserved.

Figures

Figure 1:. Number of abdominal and moderate/severe pelvic floor tender areas among endometriosis and chronic pelvic pain patients.

Blue = abdominal; Orange = pelvic floor; Abdominal tenderness assessed at right/left upper abdomen, right/left lower abdomen, suprapubic area, and umbilical area. Pelvic floor tenderness assessed at right/left pubococcygeus, right/left iliococcygeus, and right/left coccygeus muscles. Moderate/severe pelvic floor tenderness based on pain rating of ≥4 on a 0–10 pain scale at a specific tender area.