INTRODUCTION

Pelvic pain is one of the most common and debilitating symptoms associated with endometriosis.¹ Dysmenorrhea is reported by most women with endometriosis, with an estimated prevalence of nearly 80%.² Other common painful experiences in endometriosis include dyspareunia, dysuria, dyschezia, and non-cyclical pelvic pain.² For further information on the prevalence of pelvic pain in endometriosis please refer to the ‘Endometriosis Symptoms and Signs’ chapter (S Missmer).

Pain may extend beyond the pelvis, either co-occurring with other localized pain conditions (e.g. migraine or trigeminal neuralgia) or as part of a widespread picture of pain (e.g. fibromyalgia). Pain psychology is likely to be particularly important for endometriosis-associated pain co-occurring with other pain conditions, or where there are features suggesting involvement of the central nervous system (e.g. fatigue, cognitive problems, depression, hypersensitivity),³ also referred to as central sensitization.

Pain significantly affects the experience of living with endometriosis. Compared to those with asymptomatic endometriosis individuals with pain have a lower quality of life and poorer mental health.⁴ Pain is a complex biopsychosocial experience: psychological factors are central to the experience of pain and psychological approaches are a core component of pain management.⁵ In most chronic pain conditions, pain experience (severity, intensity, related distress and disability) is not directly related to disease severity, and there is evidence to suggest this is the case in endometriosis-associated pain. For example, standard treatments for endometriosis (surgery, hormones, analgesia) often do not resolve pain,^6,7 particularly for those with higher degrees of centralized pain (as indicated by higher fibromyalgia scores).⁸ Furthermore, endometriosis (particularly stage I) has been observed in women who are asymptomatic and undergoing laparoscopy for other reasons.^9,10 The conclusion of a recent systematic review highlights that there is “a lack of clear, consistent data concerning the long-term pain relief that patients may expect following medical or surgical treatment for endometriosis”.⁷ This evidence highlights the need to explore alternative approaches for the management of endometriosis-associated pain, such as pain psychology.

A psychological approach for the management of endometriosis-associated pain should be considered integral to pain management. Rather than being considered as an alternative to medical and surgical approaches (see chapters ‘Hormonal Management of Endometriosis-associated Pain’ and ‘Surgical Management of Endometriosis-associated Pain’), pain psychological should be viewed as augmenting other interventions and treatments. The timing and sequence of pain psychology when provided as part of a holistic, interdisciplinary approach, is important to consider and this is discussed later in this chapter.

DEFINITION AND CLASSIFICATION OF PAIN

Pain is defined as “an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage”.¹¹ The following six key notes are provided to give important contextual information:

• Pain is always a personal experience that is influenced to varying degrees by biological, psychological, and social factors.
• Pain and nociception are different phenomena. Pain cannot be inferred solely from activity in sensory neurons.
• Through their life experiences, individuals learn the concept of pain.
• A person’s report of an experience as pain should be respected.
• Although pain usually serves an adaptive role, it may have adverse effects on function and social and psychological well-being.
• Verbal description is only one of several behaviors to express pain; inability to communicate does not negate the possibility that a human or a nonhuman animal experiences pain.

This definition indicates that psychological factors, including thoughts, beliefs, emotions and learning, are important in the experience of pain. Endometriosis-associated pain is classified as a chronic secondary visceral pain condition.¹² All pain persisting beyond 3 months considered ‘chronic’ as opposed to ‘acute’ pain which has a duration of less than 3 months.

KEY CONCEPTS IN PAIN PSYCHOLOGY

Evidence to inform the application of pain psychology in endometriosis-associated pain specifically is limited, and research into the management of general chronic pain is much more developed. Although this has primarily focused on musculoskeletal pain conditions, there are theoretical reasons and research evidence to suggest that much of the understanding from other chronic pain conditions is relevant for those with endometriosis-associated pain. Key concepts from general pain psychology are introduced below, followed by specific considerations for endometriosis-associated pain. These concepts are used to inform pain psychology assessments and interventions.

General pain psychology

Fear and avoidance play important roles in chronic pain, with pain-related fear driving behavioral avoidance which in turn results in reduced activity, physical deconditioning, pain disability, emotional distress and lower quality of life.^13,14 The fear-avoidance model is well evidenced in musculoskeletal pain¹⁴ and early evidence of its relevance in pelvic- and sexual-pain.¹⁵

Pain catastrophizing is an automatic and habitual pattern of thinking in which pain is associated with a high level of threat.¹⁶ As in other chronic pain conditions, pain catastrophizing is prevalent at clinically relevant levels in women with chronic pelvic pain.¹⁷ Increased pain catastrophizing has been found to be associated with higher pain ratings and reduced quality of life, independently of other psychological comorbidities and pain intensity.^17,18 Although the term and concept of ‘catastrophizing’ is commonly referenced in research and is well-evidenced, it is not commonly used in clinical practice. The meaning may be misinterpreted, and it can be experienced as unhelpful and pejorative. However, understanding thoughts and beliefs (including worries) about pain is integral to a pain psychology approach.

Self-efficacy, or an individual's belief that they are able to carry out particular behaviors and exert control over ones’ life, influences pain experience.¹⁹ In those living with endometriosis, self-efficacy has been shown to be related to psychological health²⁰ and greater self-efficacy is associated with improved physical and mental quality of life.²¹

Helplessness, feeling unable to do anything to help oneself or influence one situation, is an important psychological construct related to self-efficacy.²² Increased helplessness is associated with increased pain-related symptoms, lower quality of life, and depressed mood.²³

Attentional bias for pain-related information plays an important role in pain experience. Humans have an inbuilt negative attention bias which predisposes a tendency to select (focus on and remember) pain related information over non-pain related information. This bias is argued to increase the salience of pain, enhance fear and catastrophizing, motivate avoidance of painful activities, and increase disability.²⁴ Numerous studies provide empirical support for attention bias as a key cognitive mechanism underlying adverse outcomes associated with pain catastrophizing.²⁵

Endometriosis-associated pain specific concepts

Stigma may be particularly prevalent in endometriosis-associated pain due to societal discourse around menstruation, (in) fertility and the normalization of gynecological pain.^26,27 Emotional experiences which are strongly associated with stigma and social interactions, such as shame and embarrassment, may be more commonly experienced in endometriosis-associated pain and therefore require specific attention.

Body image has received relatively little attention in pain psychology and endometriosis research until recently, but there is emerging evidence that endometriosis is associated with dissatisfaction with body appearance, particularly when accompanied by pain.²⁸

PAIN PSYCHOLOGY ASSESSMENT

A comprehensive pain psychology assessment should cover a wide range of topics. It is important to ensure the person is aware of this and understands the rationale from the outset. If this is not well understood, there is a risk that the assessment process will be experienced as invalidating, dismissive or confusing. Providing at least a minimal level of pain education prior to a pain psychology assessment is considered essential for engagement.

Suggested approach and information to convey at the start of a pain psychology assessment:

• Validate pain experience and provide reassurance that you know their pain is real.
• State that it is helpful to gain a detailed understanding of their experience of pain, but it is also helpful understand about their life/experiences more broadly. This will contribute to an understanding of the impact of pain and guide what will be helpful and meaningful going forwards.
• Explain that chronic pain is a complex and individual experience, and that it involves multiple factors – biological, psychological and social. Endometriosis is one of these factors but it will be helpful to explore what else might be playing a role.
• Highlight the connection between the mind and the body and give examples that illustrate this: for example, bladder and bowel symptoms with interviews or exams; holding tension in the body at times of stress (clenched jaw or shoulder tension); the impact of disturbed sleep on mood.
• Take a collaborative approach, combining expertise as a health-care professional with recognition that the patient brings unique knowledge about their experience of pain and life history.

Topics to cover:

• Pain description: including onset, duration, location, distribution, intensity, frequency and quality; triggers for pain/exacerbation of symptoms.
• Impact of pain: activities of daily living; physical activity/exercise; employment/education; mood; relationships, family, friends and social functioning; hobbies/leisure activities; and life roles.
• Comorbid symptoms: fatigue, sleep, memory, bladder and bowel symptoms.
• Treatment history: previous treatments (including medications, surgery physiotherapy, psychological therapy, and any other treatments tried) and their outcome; experiences of help-seeking and interactions with healthcare professionals.
• Personal history: losses, challenges and significant life events during childhood/adolescence; own and family history of pain and illness.
• Thoughts and beliefs: beliefs about and understanding of pain; beliefs and expectation about health care and treatment; self-efficacy; control; helplessness; and body image.
• Affect: low mood; anxiety; worry; stress; anger; shame; frustration; ability to relax and feel at ease (current and historical/pre- and post-onset of pain).
• Mental health: identification of mental health issues which may present a significant barrier to pain psychology, such as eating disorders, post-traumatic stress disorder drug and alcohol misuse, and psychotic disorders.
• Coping strategies and support: identification of action taken or approaches to pain management, particularly attending to avoidance or over-activity; use of medication, rest, relaxation, distraction and any other strategies.
• Goals and expectations for pain psychology, other pain management approaches and the future.

Useful questions to ask:

• What thoughts or worries do you have about the pain you are experiencing? Prompt relating to fertility concerns: do you have worries about the future? Or your health?
• What goes through your mind when you are in pain/during a flare?
• How does pain impact on how you feel and your confidence? – prompt to a range of topics: what about your body? In relationships? At work?
• What does pain stop you from doing? – prompt relating dyspareunia: does it impact on sexual intimacy?
• If you weren’t experiencing pain, what would you be doing or what would be different in your life?

INTRODUCING PAIN PSYCHOLOGY TO PATIENTS: PAIN EDUCATION

Everyone living with chronic pain should be provided with information to help them understand their condition and this will include information about psychological factors. Key information to provide in pain education includes:²⁹

• Pain is always real.
• A sensitized nervous system leads to an overprotective pain response.
• Pain doesn’t equal tissue damage: pain doesn’t have to mean there is disease or damage in the pelvis (although sometimes it does).
• Pain depends on the context: thoughts, beliefs, emotions and understanding of pain changes the experience of pain.
• It is possible to change pain.

Improved understanding of pain at an early stage is likely to be beneficial for numerous reasons, including:

• Increased awareness of the range of strategies for pain management and increased patient choice.
• Improved understanding of the need for an active role and awareness of the importance of self-management strategies.
• Expectation management through improved understanding of (possibly limited) pain relief gain through medical or surgical management alone.
• Increased hope of the possibly of change.

A biomedical approach in isolation suggests that pain is entirely attributable to disease or pathology and does not acknowledge potential impact of a broader range of contributors, such as psychosocial factors. This may unhelpfully reinforce the idea that pain is an indicator or damage or disease and result in a narrow focus to surgical or medical management. Should such interventions not offer the sustained level of pain reduction hoped for, patients are likely to feel disappointed or confused; they may have reduced confidence in healthcare and fear that pathology has been missed or inadequately treated. Pain education should be provided in advance of all interventions, including surgery.

PSYCHOLOGICAL INTERVENTIONS FOR ENDOMETRIOSIS-ASSOCIATED PAIN

Psychological therapy is an important component of treatment for many long-term physical health conditions. There is clear evidence that psychological therapy has beneficial effects for reducing pain, disability and distress in chronic pain and is a recommended treatment for chronic primary pain conditions.³ There is some evidence that psychological therapies are effective interventions in pelvic pain, including endometriosis-associated pain specifically.

Psychological interventions require patients to play an active role in their treatment and therefore a good level of engagement is key. Ensuring patients understand pain psychology through education is an essential foundation. If patients and/or health care professionals believe that significant and sustained pain relief will be gained through a surgical or medical approach, motivation to invest time and energy in a psychological approach is likely to be limited.

Interventions may be offered on either a group or individual basis; there is insufficient evidence to recommend one over the other. Group interventions are widely offered for chronic pain and, in addition to being a cost-effective mode of delivery, offer opportunities to for reduced isolation, peer-support and hearing the perspectives of others in similar situations. Individual therapy allows for a more individually tailored approach and may be preferred by those with difficulties with trust or social anxiety.

Cognitive behavioral therapy (CBT) is a time-limited, problem focused, goal orientated approach in which therapist and patient work collaboratively to understand and address unhelpful patterns.³⁰ Behavioral techniques include activity scheduling, graded exposure, behavioral experiments. Cognitive approaches include cognitive restructuring, problem solving, and imagery rescripting. There is clear evidence indicating CBT has beneficial effects (albeit small) for reducing pain, disability, and distress in chronic pain.³¹ There is emerging evidence that CBT is an effective treatment for chronic pelvic pain,^32,33 and for endometriosis-associated pain and distress specifically.³⁴

Acceptance and commitment therapy (ACT) is a behavioral therapy focused on developing psychological flexibility through a range of strategies including acceptance and values-based behavioral change.³⁵ ACT is an effective intervention for chronic pain³⁶ and vulvodynia.³⁷ There is no direct evidence for benefits in endometriosis-associated pain as yet.

Mindfulness-based interventions focus on developing a new relationship with experience characterized by present moment focus, decentering and an approach orientation; they also support the development of qualities such as compassion, wisdom, equanimity and greater attentional, emotional and behavioral self-regulation.³⁸ A mindfulness-based intervention has been shown to result in a reduction in endometriosis-associated pelvic pain, dyschezia and pain unpleasantness, compared to controls post treatment and at follow-up.³⁹ There are also studies which demonstrate benefits dyspareunia and vulvodynia.⁴⁰

Compassion focused therapy (CFT), originally developed with the purpose of treating depression with high levels of shame.⁴¹ Given the culture of secrecy and feelings of shame associated with endometriosis and associated pain but evidence for CFT in the management of pain is currently lacking.

DYSPAREUNIA AND SEXUAL DYSFUNCTION

The World Endometriosis Society highlights dyspareunia and sexual function as important areas for attention. Dyspareunia, defined as pain before, during or after intercourse, is experienced by over 40% of people with endometriosis.⁴² Sexual function is linked to quality of life: sexual dysfunction is associated with poorer mental health, is a predictor of depression and also impact on quality of partner relationships. Assessment and treatment of dyspareunia presents a challenge for both patients and clinicians, with both parties often feeling reluctant to discuss it.

The biopsychosocial model which is widely recognized as a helpful model in the field of pain can also provide a valuable framework for understanding sexual function.

• Biological factors include hormones, the central nervous system and musculoskeletal system, including pelvic floor.
• Social and cultural factors include gender roles and social expectation. The belief that gynecological or sexual pain is to be tolerated is common in many cultures and should be explored.
• When considering sexual function, it is natural to focus attention on the person with the health condition. However, it is important to consider relationship factors. Many partners also develop concerns about painful intercourse and may lose confidence, feel anxious or avoidant. They too can experience sexual dysfunction. Wider issues in the relationship may also play an important role, including trust, communication and intimacy. A relationship or couples focussed therapy may be needed in the first instance for some.
• Sexual factors include sexual pain, but also difficulties with desire arousal or orgasm. The consequences of chronic dyspareunia are significant:⁴³ pain will (naturally) result in learning that sexual experiences are to be avoided; when they are encountered, they are unlikely to lead to arousal because of concern about an anticipated painful outcome; emotional intimacy is impacted because of repeated feelings of being hurt and sadness, hurt and frustration replace feelings of closeness.
• There are multiple psychological factors, including thoughts, beliefs and emotions that will significantly impact on sexual function. Pain-related psychological factors (as described above) are important to consider but will also be important to explore psychological factors related specifically to sexual intimacy.

CO-MORBID MENTAL HEALTH DIFFICULTIES

Physical and mental health are closely related, and endometriosis-associated pain is associated with a high prevalence of psychological distress.⁴⁴ Psychological approaches for pain management allow attention to wider psychological distress (such as depression and anxiety) and many of the interventions employed in pain psychology are also evidenced to be effective for common mental health difficulties. A pain psychology approach is likely to have benefits for mental health, and vice versa. Whether a pain or mental health approach is taken will be influenced by various factors including: patient and health care professional view of the primary presenting problem; goals for treatment; resources available in mental health or pain management services; and severity of pain and mental ill-health.

In some circumstances mental health difficulties may present a significant barrier to a pain psychology approach and therefore may require direct treatment prior to a pain psychology approach. Specific issues to consider in assessment include:

Severe depression associated with very low levels of activity and high hopelessness.

Eating disorders particularly when associated with very low weight or significant ongoing weight loss. Some purging behaviors, such as vomiting or laxative use, may perpetuate visceral sensitivity or pelvic floor dysfunction.

Post traumatic stress disorder (PTSD) is characterized by re-experiencing symptoms (e.g. flashbacks and nightmares), hypervigilance and avoidance. Whether assessment (e.g. vaginal examinations) or interventions (e.g. pelvic physiotherapy) for endometriosis-associated pain could potentially serve as triggers for re-experiencing symptoms should be considered, particularly when there is a history of sexual trauma.

Sleep disturbance commonly co-occurs with pain and mental health difficulties. Good sleep hygiene should be encourage for all and some may benefit from specific sleep-focus psychological interventions (CBT for insomnia).

Severe mental illness (SMI), such as psychosis, is associated with a high prevalence of pain but this relationship is complex and under-researched.⁴⁵ Care for those with SMIs and co-morbid endometriosis-associated pain is likely to be optimized when health care professions from a range of specialities (pain, gynecology and mental health) work closely together and interventions are individually tailored to accommodate the complex needs of the person.

TRAUMA AND TRAUMA INFORMED CARE

Harmful experiences such as abuse, violence and neglect are common in the general population and adverse childhood experiences (ACEs) are experienced by many. The lasting affects of adversity are well-established, with known impacts on an individual’s functioning and mental, physical, social, emotional or spiritual well-being. High levels of ACEs are seen in those seeking support for chronic pain⁴⁶ and in those living with endometriosis.⁴⁷

Trauma-informed care assumes that people have had traumatic experiences, and as a result may find it difficult to feel safe within services and to develop trusting relationships with health-care providers. All services, including services for people with endometriosis, should structure and deliver care in ways that promote safety and trust and aim to prevent retraumatization. Trauma-informed care is different from trauma-specific services which are designed to treat the impact of trauma using specific therapies and other approaches. Individuals with ongoing PTSD may want or need to access trauma-specific services in addition to pain-focused psychological support. However, it is important to note this is not always necessary and may not be the patients choice.

PRACTICE RECOMMENDATIONS