Chronic pelvic pain

Section 1: Aetiology and epidemiology

Section 1: Aetiology and epidemiology

Chronic pelvic pain is defined as intermittent or constant pain in the lower abdomen or pelvis, of at least six months' duration, not occurring with menstruation or intercourse and not associated with pregnancy (see box).

Understanding pain
Pain is defined by the International Association for the Study of Pain as an 'unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage'. 3

In chronic pain, the sensation may persist long after the primary noxious stimulus, or can exist in its absence. This is in contrast to acute pain, which is sensed in response to fresh tissue damage and resolves on removal of the causative factor.

Descending information from the CNS, shaped by past experiences and current surroundings, may alter pain perception and, as pain becomes chronic, involve a greater area than initially affected. Local nerve damage can contribute to this process.4,5

The experience of pain will therefore be affected by physical, psychological and social factors, and each of these should be explored when the patient presents to the clinician.

Making an assessment
Many women begin the consultation with preconceived ideas about the cause of their symptoms and it is vital to address these at the start of any dialogue.6

It is important to characterise the pain initially in terms of location, severity and distribution.

Precipitating factors should be explored, as well as anything that the patient feels alleviates symptoms.

A complete abdominal, vaginal and, where indicated, rectal examination should be performed. Where history or examination suggest that the cause of pain is non-gynaecological, the patient should be referred as necessary.

Chronic pelvic pain

  • Chronic pelvic pain has an estimated prevalence of 38 per 1,000 in women aged 15-73 years, comparable to that of asthma (37 per 1,000) and chronic back pain (41 per 1,000).1
  • It is the single most common indication for referral to gynaecology clinics, accounting for 20 per cent of all outpatient gynaecology appointments in secondary care.
  • Chronic pelvic pain costs the NHS £158 million per year.2

Section 2: Differential diagnoses

Women seeking a cause for their symptoms should be aware that chronic pelvic pain is a symptom of a problem, rather than a diagnosis in itself.

Endometriosis
Endometriosis is the presence of endometrial tissue outside the uterine cavity. The cause of the pain is not clear.

Clinical examination should be performed during menstruation when nodules are more easily palpable.7 Laparoscopy is required for a definitive diagnosis.

Medical treatment works by suppressing the menstrual hormonal cycle, and six months has proven to be effective.8 The levo-norgestrel coil also appears to reduce pain associated with endometriosis.8 The cessation of any type of treatment can result in recurrence.

Abnormalities
Low vaginal atresia or an imperforate hymen can result in abdominal pain because blood accumulates in the upper vagina and uterus during menses. The diagnosis is confirmed by trans-abdominal pelvic ultrasound scan and the treatment is drainage at surgery.

Chronic pelvic disease
The term chronic pelvic inflammatory disease is a misnomer - there is no evidence of an inflammatory process or continuing sepsis; this is supported by the absence of clinical, haematological or biochemical features of infection. It therefore does not respond to antibiotics.

Pain is thought to be a consequence of structural abnormalities, such as hydrosalpinges and adhesions, or paracrine changes in pelvic structures mediated through prostaglandins.

Excision or drainage of hydro-salpinges may be effective. In some, laparoscopy alone may result in improvement.

Adhesions
There is a lack of evidence that adhesions cause pain. Equally, there is little to show that laparoscopic division of adhesions can relieve it.

Chronic post-operative pain may be caused by residual ovary syndrome, where a small amount of ovarian tissue is inadvertently left behind following oophorectomy. Alternatively, chronic post-operative pain may be due to trapped ovary syndrome, in which a retained ovary becomes buried in dense adhesions following hysterectomy. Removal of all ovarian tissue or suppression using a gonadotropin-releasing hormone agonist may relieve the pain.

Nerve entrapment
Nerve entrapment is defined as highly localised, sharp, stabbing pain persisting beyond five weeks, or occurring after a pain-free interval.9 It is best treated by neuromodulating agents, such as tricyclic antidepressants.

Musculoskeletal pain may be the primary cause, or may result from altered posture as a result of pain.10

Psychological factors
Depression, anxiety, sleep disorders and somatisation all play a part in the interpretation of pain and are important to identify.11

Women with previous or current sexual abuse are more likely to present with chronic pelvic pain and sensitive questioning may therefore be appropriate.

Irritable bowel syndrome
One third of 'normal' women experience an alteration in bowel habit during menstruation, while half of women with irritable bowel syndrome (IBS) have a perimenstrual increase in symptoms.

Deep dyspareunia may occur in women with IBS but typically occurs after rather than during intercourse, due to post-coital bowel spasm. There is also an association with bladder dysfunction, particularly detrusor instability, in women with IBS.

A diagnosis of IBS can be made using the Rome criteria, which have a positive predictive value of 98 per cent (see box).

Rome criteria for IBS
At least three months of intermittent or constant pain that is relieved by defecation and associated with at least two of the following:

  • Altered stool frequency.
  • Bloating.
  • Altered stool passage - straining, urgency.
  • Altered stool form - diarrhoea, 'rabbit pellets'.
  • If symptoms are suggestive of IBS, offer dietary advice and a trial of an antispasmodic drug.

Section 3. Investigations

Investigation should be guided by the history and examination, along with the differential diagnosis, and directed towards positive findings.

It may include transvaginal ultrasonography, laparoscopy and microbiology.

Investigating
Transvaginal ultrasonography is an appropriate mode of investigating a pelvic mass secondary to endometriosis. It can accurately distinguish endometrioma from other adnexal lesions.

It will not show endometriosis lesions on the peritoneum. Adenomyosis can be diagnosed with similar sensitivity with MRI and pelvic ultrasound.12

Laparoscopy
Laparoscopy, the previous gold standard, should now be a second-line investigation. There is evidence that simply to undergo laparoscopy can improve a woman's pain score, regardless of whether findings are positive or negative. The overall risk-to-benefit ratio must be balanced.

Microbiology
Microbiology can screen for infection, in particular gonorrhoea and Chlamydia.

If PID is suspected clinically at this stage, refer to a genitourinary clinic for contact tracing and access to current treatment because this may prevent hydrosalpinx and adhesions.

Section 4. Therapeutic options

The therapeutic aims in a patient with pelvic pain should focus on relief or management of symptoms aiming to restore normal function.

Pain management
Women who have been given a pain management strategy and who have access to services including psychological- and physiotherapy-based treatments have shown improved long-term pain scores, as well as an ability to work and reduced analgesia intake.13

Pain control should be addressed in all women, even where no other treatment options are planned. Simple and compound analgesics can be safely used with good symptom relief.

Regular NSAIDs are useful because of their inhibitory affect on cyclo-oxygenase in the prostaglandin synthesis pathway.

Neuropathic pain
Neuropathic pain can be addressed with gabapentin or amitriptyline; non-pharmacological options including acupuncture.14

If this fails in primary care, refer to a specialist pain clinic.

Endometriosis
A trial of ovarian suppression should be offered in cases of suspected endometriosis where severe disease or endometriomas are not suspected.

Hormonal treatments have been shown to be of equal efficacy and the choice will be influenced by the side-effect profile, relative or absolute contraindications and the patient's wishes.

This article was originally published in MIMS Women's Health. To register to receive copies go to www.hayreg.co.uk/specials

Key points

  • Chronic pelvic pain is a common problem with the aetiology remaining unclear and requiring further elucidation.
  • The conditions giving rise to chronic pelvic pain are diverse and many patients will have no obvious pathology.
  • An integrated approach that encourages the patient to participate in her own management from the outset has been shown to improve pain scores following investigation and treatment.
  • Treatment should be directed towards the likely problem, with appropriate referral where indicated.
  • Contributed by Dr Susanna Crowe, specialist registrar, Dr Bryn Kemp, SHO, and Mr Antonios Antoniou, consultant gynaecologist and obstetrician at Newham University Hospital, London.

Resources:

Further reading
RCOG Guideline 41: The initial management of chronic pelvic pain. April 2005. Available from: www.rcog.org.uk/index.asp?PageID=1124

References

  1. Zondervan K, Yudkin P, Vessey M et al. Prevalence and incidence of chronic pelvic pain in primary care: evidence from a national general practice database. Br J Obstet Gynaecol 1999; 106: 1,149-55.
  2. Davies L, Ganger K, Drummond M et al. The economic burden of intractable gynaecological pain. J Obstet Gynaecol 1992; 12: 46-54.
  3. International Association for the Study of Pain. Pain terms: a current list with definitions and notes on usage. Pain 1986; 24 Suppl 1: S215-21.
  4. McMahon S, Dmitrieva N, Koltzenburg M. Visceral pain. Br J Anaesth 1995; 75: 132-44.
  5. Wesselmann U. Neurogenic inflammation and chronic pelvic pain. World J Urol 2001; 19: 180-5.
  6. Selfe S, Matthews Z, Stones R. Factors influencing outcome in consultations for chronic pelvic pain. J Womens Health 1998: 7: 1,041-8.
  7. Koninckx P, Meuleman C, Oosterlynck D, Cornillie F. Diagnosis of deep endometriosis by clinical examination during menstruation and plasma Ca-125 concentration. Fertil Steril 1996; 65: 280-7.
  8. RCOG. Green-top Guideline 24. The investigation and management of endometriosis. Oct 2006.
  9. Perry C. Peripheral neuropathies causing chronic pelvic pain. J Am Assoc Gynecol Laparosc 2000; 7: 281-7.
  10. King P, Myers C, Ling F, Rosenthal R. Musculoskeletal factors in chronic pelvic pain. J Psychosom Obstet Gynaecol 1991; 12: 87-98.
  11. Bak A, Drogendijk A, Voitus van Hamme J et al. Chronic pelvic pain and neurotic behaviour. J Psychosom Obstet Gynaecol 1990; 11: 29-35.
  12. Dueholm M, Lundorf E, Hansen E et al. Magnetic resonance imaging and transvaginal ultrasonography for the diagnosis of adenomyosis. Fertil Steril 2001: 76: 588-94.
  13. Albert H. Psychosomatic group treatment helps women with chronic pelvic pain. J Psychosom Obstet Gynaecol 1999; 20: 216-25.
  14. The Pain Society. Recommendations for the appropriate use of opioids for persistent non-cancer pain. March 2004.

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