You refer a 25-year old woman with chronic pelvic pain to the gynaecology department, thinking that she might be suffering endometriosis. A few months later, you receive discharge summary stating that she has had a laparoscopy which was entirely normal. The letter states, ‘We have been unable to find a gynaecological cause for her pain and we have asked her to discuss further investigation with you if she continues to experience symptoms.’
Where do you go from here? How can she be managed going forward? What other assessment or investigation might be appropriate?
Chronic pelvic pain (CPP) in women is defined by the Royal College of Obstetricians and Gynaecologists (RCOG) as intermittent or constant pain in the lower abdomen or pelvis of a woman of at least six months in duration, not occurring exclusively with menstruation or intercourse and not associated with pregnancy.1 The prevalence of CPP in women is difficult to determine, but it is estimated that up to 38 per 1000 women are affected annually in the UK.2 Global estimates range from 2.1% to 24% of the female population.3
CPP is often multifactorial in nature. Several pelvic conditions are associated with CPP, however treating them may not always improve symptoms, questioning their causality. These include endometriosis, adenomyosis, pelvic inflammatory disease, pelvic adhesions, functional disorders of the bowel (including irritable bowel syndrome) and the bladder (bladder pain syndrome, previously referred to as interstitial cystitis). Other common problems are associated with CPP, including dysfunction of the musculoskeletal system and nerve entrapment. Up to 40-55% of women with chronic pelvic pain in secondary care appear to have no apparent underlying pathology based on clinical history, examination, and investigations. These women are often referred to as having chronic pelvic pain syndrome (CPPS).4,5 Like many pain syndromes, the pathology is thought to lie within the nervous system and pain processing, rather than from a peripheral gynaecological source.
The psychosocial context of the patient is important. Nearly 50% of women seeking care for CPP report a history of sexual, physical, or emotional trauma, and about 30% have positive screening results for post-traumatic stress disorder.6
Approach to women with chronic pelvic pain
Pain is subjective and as such, it can be difficult to assess objectively. A detailed history and examination (with or without baseline investigations) may provide clues to the underlying cause of their pain. It may be appropriate to explore any underlying psychological disorders that invariably exacerbate chronic pain.
Women with a gynaecological pathology, e.g. adenomyosis or endometriosis, may have pain linked with changes in the menstrual cycle. However, pain arising from other organ systems including the bladder and bowel can also be influenced by hormonal changes, so this observation is not diagnostic.7-9 Women with CPP unrelated to the menstrual cycle may have pain originating from other sites in the pelvis, e.g. adhesions, irritable bowel syndrome, interstitial cystitis/bladder pain syndrome or musculoskeletal pain. It is crucial to identify red flag symptoms (see chart A), that may necessitate an urgent specialist review.
When assessing women with CPP, you should conduct a gentle physical examination and an internal pelvic examination. A speculum examination should not be routinely performed. It should be undertaken if there are any concerns about abnormal genital tract bleeding or discharge. If there are no red flag symptoms, it may be appropriate to delay this component of the examination until a later appointment if it would be considered too traumatic. Pelvic examinations can often result in exacerbation of pain. In addition to a standard examination, special attention should be paid to assessing trigger points present within either the pelvic floor or abdominal muscles. Tender points on bony sites (sacroiliac joints, pubic symphysis), may indicate a musculoskeletal cause of pain. It is important that these assessments are performed prior to examining deeper within the pelvis, as it may become difficult to distinguish whether abnormal musculoskeletal findings were initially present or have arisen as a protective mechanism in response to the pelvic examination.
The International Pelvic Pain Society has developed a detailed history and physical examination form with tools for quantifying and mapping of pelvic pain, screening questionnaires, and an extensive review of the common body systems that may be responsible.10 Chart A provides an overview of managing women with CPP.
Management of women with chronic pelvic pain
Women with CPP often have disturbed sleep, reduced mobility, anxiety and depression, and limited work and social function, all of which can negatively affect their quality of life. The RCOG, therefore, recommends a combination of pharmacological interventions, physiotherapy, and pain psychology for women with CPP.1 An assessment of mental wellbeing should be considered due to the recognised impact of CPP on mood – the Patient Health Questionnaire (PHQ-9) or similar may be used.11 Women with a high score should be referred for psychological support.
The recommended drug therapy in women with CPP is summarised in table 1.
|Inflammatory||NSAIDs e.g. ibuprofen, mefenamic acid||Useful in women with superimposed dysmenorrhea and CPP
Ibuprofen 400mg tds/qds from cycle day 1-4
Mefenamic acid 250-500mg tds from cycle day 1-4
|Neuropathic pain||Tricyclic antidepressants e.g. amitriptyline, nortriptyline||Amitriptyline (starting dose 10-25mg od), increased weekly to 50-150mg od (1-2 divided doses)
Nortriptyline 10mg od, to be taken at night, increased weekly if necessary, to 75mg daily
|Neuropathic pain||Gabapentinoids e.g. Gabapentin, pregabalin||Pregabalin 75mg bd increasing after 1-2 weeks up to 150mg bd
Gabapentin 300mg od, increased weekly to 600-900mg tds
|Neuropathic pain||Serotonin-norepinephrine reuptake inhibitors e.g. Duloxetine||Initially 30mg od, increased after two weeks if necessary, to 60mg od; maximum 120mg per day|
Table 1 – Adapted from12
Neuromodulators primarily affect processing of pain by the central nervous system, in contrast with NSAIDs, for example, which act on peripheral mediators of inflammation. Neuroimaging studies have shown gabapentinoids to affect brain function. Like most neuromodulators, gabapentin and pregabalin are only licensed for peripheral neuropathic pain and their use in chronic pelvic pain is off-licence. Although the current evidence is limited, the large multicentre GaPP2 trial aims to clarify the effectiveness of gabapentin in women with CPP with no identified underlying pathology.13 Opiates should be used cautiously and in conjunction with the advice from a pain medicine specialist.
The importance of healthy lifestyle measures should not be underestimated in women with CPP. However, there is no scientific basis to guide women or support dietary measures for the treatment of CPP specifically. Avoiding processed foods, alcohol and smoking, as well as choosing fresh, naturally available foods with a wide range of vegetables may benefit some women with CPP. Anecdotally, patients report benefits from adopting a FODMAP diet. Exercise, even in small amounts can improve confidence, body image and enhance mobility. The release of endorphins associated with exercise may alter central pain perception. Often women with CPP seek reassurance, and exclusion of pathology using simple measures such as blood tests and pelvic ultrasound surveillance may benefit. Cochrane suggests women who underwent reassurance ultrasound scans and received counselling were more likely to report improved pain than those treated with a standard ‘wait and see’ policy.14
Physical modalities to improve pelvic floor dysfunction, such as biofeedback and pelvic floor physiotherapy, may help women with CPP. Pelvic floor trigger points have also been managed with electrostimulation and pelvic floor massage. A referral to a physiotherapist with experience managing these complex cases may be indicated in well-phenotyped patients.
Cognitive behavioural therapy (CBT) is recommended by the RCOG and is integral to managing women with CPP alongside other interventions. Somatocognitive therapy combines physiotherapy and CBT in managing CPP.
Complementary therapies such as Chinese medicine, acupuncture and electroacupuncture may be of benefit. Traditional acupuncture believes that energy called ‘chi’ flows in the body and that acupuncture can be used to rebalance the flow of chi. Electroacupuncture is a method of stimulating acupuncture points with an electrical microcurrent attached to the needles. It promotes the release of endogenous neurotransmitters such as beta-endorphin, a natural analgesic.
Dr Rohan Chodankar is a clinical research fellow in obstetrics and gynaecology at the Queen’s Medical Research Institute, Edinburgh.
Dr Lorraine Harrington is a consultant in anaesthesia and pain medicine at NHS Lothian.
Professor Katy Vincent is a senior pain fellow at the University of Oxford and locum consultant in gynaecology.
Professor Andrew W Horne is a professor of gynaecology and reproductive sciences at the Queen’s Medical Research Institute