Endometriosis is a chronic recurrent disease characterized by the growth and implantation of endometrial tissue outside the uterine cavity. Previous studies suggest that endometriosis affects 1 in 10 women of reproductive age, and it has been estimated that 176 million women worldwide suffer from this disease. This pathology entails a series of functional and psychological changes that can affect sexual function and have a negative impact on a woman's engagement on physical activity as well as their general health-related quality of life (1). The different treatments for endometriosis entail significant direct and indirect costs derived from medical and surgical treatments. Conservative approaches appear to be promising in helping to restore adequate functionality, thus improving symptoms such as pain relief. However, the literature is preliminary and sparse, and more research is needed in this field. Therefore, it is necessary to analyze the functional and psychological characteristics at the sexual sphere of women with endometriosis, compared to women without endometriosis, in order to identify potential targets for rehabilitation interventions. 

The main aim of this observational study was to investigate whether women with endometriosis present worse pelvic floor muscle (PFM) function compared to women without endometriosis, and also whether a higher level of catastrophism is a determining factor in sexual function and physical activity.

A cross-sectional study was conducted on xxxxxxx of the xxxxxx of the xxxxxxx and women aged 22-48 years old participated. Women with endometriosis (n=17) were compared to age-matched women without endometriosis (n=13). Both groups attended a one-single assessment session. Firstly, socio-demographic and clinical data were recorded (age, type of endometriosis, and surgeries) (Table 1) as well as exercise intensity classification. Then assessments included: PFM function (tone and contraction) using a Pelvimeter (Pelvimeter, Phenix, Montpellier, France), sexual function with Abbreviated Female Sexual Function Index (FSFI-6) (scores range from 2 to 30, with lower scores indicating worse sexual functioning) (2), and the Pain Catastrophizing Scale (PCS) (scores range from 0 to 52) to evaluate negative thoughts in relation to pain and pathology (3). 
The inclusion criteria for the endometriosis group (EG) were: having a medical diagnosis of endometriosis, age between 18-50 years, nulliparous, having passed a period equal to or greater than 3 months since the last surgery. The exclusion criteria were: pregnancy, diagnosis of autoimmune or neurological diseases, menopause, previous abdominal and/or lumbar and/or pelvic surgery. 
For the control group, the inclusion criteria were: nulliparous, not have incapacitating menstrual pain, fibroids, infertility, or uterine malformations. 

Sample size was calculated with the G*Power 3.1.9.7 program. An “a priori” analysis was conducted and a power of 80%, an effect size of 0.75 and a statistical power of 0.80 and with an α=0.05 were established. This resulted in a minimum sample size of twenty-three participants per group.

In this pilot study, a total of 20 nulliparous women were included (EG = 17), (CG = 13), with a mean age of 32. No significant differences were observed in PFM tone and contraction values (p>0.05) between the EG and the CG. The FSFI-6 score in the EG was 18.18 ± 6.3 points, compared to 24.38 ± 3.45 in the CG, with significant differences (p<0.05). Exercise intensity showed significant differences between-groups, with higher intensity levels in the CG (p<0.05). Finally, between-groups significant differences were obtained in the PCS total scores ((p<0.05) with higher values in women with endometriosis (22.65 points compared to 5.5 in the control group) (Table 2).

Although there are no differences in the PFM tone and its functionality between both groups, our results can explain that catastrophism entails erroneous ideas and fear of movement, which translates into poor sexual function and avoidance behaviors towards the practice of intense physical exercise in women with endometriosis. 

Pain catastrophizing includes cognitive, emotional, and behavioral processes (fear-avoidance behaviors, altered mood and motivation) that amplify perceived painful sensations and predispose to the perpetuation of pain. Women who catastrophize have negative thoughts about their pain, and constantly focus their attention on it, feeling helpless in relation to it.

Endometriosis causes pain and disability in many women who suffer from it. This, associated with the lack of information and the poor results of some of the current treatments, can generate greater catastrophism in these women, with erroneous beliefs about their pain. This catastrophizing leads women to less participation in activities of daily living, such as sexual function or physical activity. However, the results of our study indicate that there is no significant difference in the tone and activity of the PFM. 

Based on these results, and the current existing evidence, we consider that it is necessary to improve pain education in these women, in order to reduce catastrophizing and improve physical condition and sexual function.

Van Niekerk L, Steains E, Matthewson M. Correlates of health-related quality of life: The influence of endometriosis, body image and psychological wellbeing. J Psychosom Res. 2022;161:110993. doi:10.1016/j.jpsychores.2022.110993
Mateu Arrom L, Girabent-Farrés M, González M, Palou J, Errando-Smet C, Ramírez-García I. Development and validation of a short version of the Female Sexual Function Index in the Spanish population. BMC Womens Health. 2021;21(1):63. doi:10.1186/s12905-021-01213-8
García Campayo J, Rodero B, Alda M, Sobradiel N, Montero J, Moreno S. Validación de la versión española de la escala de la catastrofización ante el dolor (Pain Catastrophizing Scale) en la fibromialgia. Medicina Clínica. 2008;131(13):487-492. doi:10.1157/13127277