Are pelvic pain and increased pelvic floor muscle tone associated in women with persistent noncancer pelvic pain? A systematic review and meta-analysis.

BACKGROUND: The association between pelvic pain and pelvic floor muscle (PFM) tone in women with persistent noncancer pelvic pain (PNCPP) is unclear. AIM: To synthesize the evidence of the association between pelvic pain and PFM tone in women with PNCPP. METHODS: A systematic review was conducted via MEDLINE, Emcare, Embase, CINAHL, PsycINFO, and Scopus to identify relevant studies. Studies were eligible if pelvic pain and PFM tone outcome measures were reported among women aged >18 years. The National Heart, Lung, and Blood Institute's Quality Assessment Tool for Observational Cohort and Cross-sectional Studies was used to assess study quality. Studies were pooled by assessment of PFM tone via a random effects model. Associations between the presence of pelvic pain and PFM tone were assessed with odds ratio (OR), while linear associations were assessed with Pearson or Spearman correlation. OUTCOMES: Pelvic pain measures (intensity, threshold, and frequency) and resting PFM tone in women with PNCPP, as evaluated by any clinical assessment method or tool. RESULTS: Twenty-four studies were included in this review. The presence of pelvic pain was significantly associated with increased PFM tone as assessed by digital palpation (OR, 2.85; 95% CI, 1.66-4.89). Pelvic pain intensity was inversely but weakly associated with PFM flexibility when evaluated through dynamometry (r = -0.29; 95% CI, -0.42 to -0.17). However, no significant associations were found between pelvic pain and PFM tone when measured with other objective assessment methods. CLINICAL IMPLICATIONS: Pelvic pain and increased PFM tone may not be directly associated; alternatively, a nonlinear association may exist. A range of biopsychosocial factors may mediate or moderate the association, and clinicians may need to consider these factors when assessing women with PNCPP. STRENGTHS AND LIMITATIONS: This review was reported according to the PRISMA guidelines. All possible findings from relevant theses and conference abstracts were considered in our search. However, nonlinear associations between pelvic pain and increased PFM tone were not assessed as part of this review. CONCLUSION: Pelvic pain may be linearly associated with increased PFM tone and decreased PFM flexibility when measured with digital palpation or dynamometry; however, this association was not observed when other aspects of PFM tone were assessed through objective methods. Future studies are required using robust assessment methods to measure PFM tone and analyses that account for other biopsychosocial factors that may influence the association.

Is there a difference in pelvic floor muscle tone between women with and without pelvic pain? A systematic review and meta-analysis.

BACKGROUND: Alterations in pelvic floor muscle (PFM) function have been observed in women with persistent noncancer pelvic pain (PNCPP) as compared with women without PNCPP; however, the literature presents conflicting findings regarding differences in PFM tone between women with and without PNCPP. AIM: To systematically review the literature comparing PFM tone in women with and without PNCPP. METHODS: MEDLINE, Embase, Emcare, CINAHL, PsycINFO, and Scopus were searched from inception to June 2021 for relevant studies. Studies were included that reported PFM tone data in women aged ≥18 years with and without PNCPP. The risk of bias was assessed with the National Heart, Lung, and Blood Institute Quality Assessment Tool. Standardized mean differences (SMDs) for PFM tone measures were calculated via random effects models. OUTCOMES: Resting PFM tone parameters, including myoelectrical activity, resistance, morphometry, stiffness, flexibility, relaxation, and intravaginal pressure, measured by any clinical examination method or tool. RESULTS: Twenty-one studies met the inclusion criteria. Seven PFM tone parameters were measured. Meta-analyses were conducted for myoelectrical activity, resistance, and anterior-posterior diameter of the levator hiatus. Myoelectrical activity and resistance were higher in women with PNCPP than in women without (SMD = 1.32 [95% CI, 0.36-2.29] and SMD = 2.05 [95% CI, 1.03-3.06], respectively). Women with PNCPP also had a smaller anterior-posterior diameter of the levator hiatus as compared with women without (SMD = -0.34 [95% CI, -0.51 to -0.16]). Meta-analyses were not performed for the remaining PFM tone parameters due to an insufficient number of studies; however, results of these studies suggested greater PFM stiffness and reduced PFM flexibility in women with PNCPP than in women without. CLINICAL IMPLICATIONS: Available evidence suggests that women with PNCPP have increased PFM tone, which could be targeted by treatments. STRENGTHS AND LIMITATIONS: A comprehensive search strategy was used with no restriction on language or date to review studies evaluating PFM tone parameters between women with and without PNCPP. However, meta-analyses were not undertaken for all parameters because few included studies measured the same PFM tone properties. There was variability in the methods used to assess PFM tone, all of which have some limitations. CONCLUSION: Women with PNCPP have higher PFM tone than women without PNCPP; therefore, future research is required to understand the strength of the relationship between pelvic pain and PFM tone and to investigate the effect of treatment modalities to reduce PFM tone on pelvic pain in this population.