Phenotyping Sexual Pain in Endometriosis Using the Central Sensitization Inventory

Introduction: Deep dyspareunia, a common symptom in endometriosis, has previously been associated with bladder and/or pelvic floor tenderness (BPFT), which suggests a role for central nervous system sensitization. The Central Sensitization Inventory (CSI, 0-100) is a validated self-reported scale for patients with central sensitization.

Aim: The objective of this study was to phenotype deep dyspareunia using BPFT and the CSI.

Methods: The methods included cross-sectional analysis from a prospective registry from January 2018 to June 2018 at a tertiary center for endometriosis (ClinicalTrials.gov #NCT02911090). Included were women aged 18-50 years with endometriosis (previously surgically diagnosed, current visualized endometrioma on ultrasound, or current palpable or visualized nodule on ultrasound), who were newly or re-referred to the center. Severity of deep dyspareunia was self-reported using an 11-point numeric rating scale (0 = no pain; 10 = worst pain imaginable), categorized as no or low deep dyspareunia (0-4) and high deep dyspareunia (5-10). We identified the subgroup with high deep dyspareunia and presence of BPFT, where we hypothesized a central component of the sexual pain. This subgroup was compared with 2 other subgroups: no or low deep dyspareunia and high deep dyspareunia but no BPFT. The CSI was compared between the groups using analysis of variance, followed by post hoc testing (P < .05).

Main outcome measure: The main outcome measure was the CSI score ranging from 0 to 100.

Results: Data from 163 women with endometriosis were analyzed. The mean age of this cohort was 36.4 ± 6.8 years, and the mean CSI score was 41.0 ± 18.6. 37 percent (61/163) had high deep dyspareunia and BPFT; 29% (47/163) had high deep dyspareunia and no BPFT; and 34% (55/163) had no or low deep dyspareunia. The CSI significantly differed between the 3 groups (analysis of variance: F = 22.4, P < .001). In post hoc testing, the CSI was higher in women with high deep dyspareunia and BPFT (51.3 ± 16.9), compared with women with no or low deep dyspareunia (30.9 ± 15.4, P < .001) and compared with women with high deep dyspareunia but no BPFT (39.4 ± 17.2, P = .001).

Clinical implications: The CSI could be used to classify and phenotype patients with endometriosis-associated sexual pain.

Strength & limitations: Strengths include a prospective registry with integrated pain scores, validated questionnaires, and physical examination findings. Limitations include the lack of quantitative sensory testing for central sensitization.

Conclusions: In women with endometriosis, the subgroup with high deep dyspareunia and bladder and/or pelvic floor tenderness had a significantly higher score on the CSI than other subgroups, suggesting that this group may have a central component to their sexual pain. Orr NL, Wahl KJ,Noga H, et al. Phenotyping Sexual Pain in Endometriosis Using the Central Sensitization Inventory. J Sex Med 2020;17:761-770.