Clinical Obstetrics and Gynaecology, 3ed.

12

Pelvic pain

Introduction

History

Examination

Acute pelvic pain

Chronic pelvic pain (CPP)

Introduction

Physiological pelvic pain with menstruation or childbirth is almost universal, but many women will present with pelvic pain for other reasons. This is most commonly acute pelvic pain, for example with appendicitis, a miscarriage or an ectopic pregnancy, but the pain may also be chronic, lasting for many months or years.

With acute pain, there is usually a well-defined pathological cause, which either resolves spontaneously or can be effectively treated. Chronic pelvic pain (CPP) is a symptom, not a diagnosis. CPP presents in primary care as frequently as does migraine or low back pain. Aiming for accurate diagnosis and effective management from the first presentation may help to reduce the disruption of the woman’s life and may avoid a seemingly endless succession of referrals, investigations and operations.

Pelvic pain is considered under the two headings of ‘acute’ and ‘chronic’, although it is important to note that there is significant overlap. Although focusing on the gynaecological causes of pelvic pain, the non-gynaecological causes are also important and it is for this reason that a multidisciplinary approach, particularly for those women with CPP, is important.

Pain

Pain is a subjective phenomenon. Many of the factors affecting pain are centrally mediated, such that pelvic pain is often made worse by psychological, psychiatric or social distress. Unlike external organs such as the skin, which contains pain sensors, the organs within the peritoneal cavity (the viscera) are sensitive to inflammation, chemicals and stretching or distortion caused by specific stimuli, for example adhesions or gaseous distension. The sensitivity of different organs to varying stimuli is an important factor influencing pelvic pain: the cervix and uterus are relatively insensitive, for example, whereas the fallopian tubes are exquisitely sensitive. Crushing of the bowel is associated with minimal discomfort, whereas stretching and distension cause severe pain. Unlike cutaneous painful stimuli, localization of visceral pain is often very difficult.

History

The history is arguably the most important factor in determining how quickly the diagnosis is reached and appropriate treatment instigated. Particular attention should be given to the time of onset of the pain, the characteristics, radiation, duration, severity, exacerbating and relieving factors, cyclicity and analgesic requirements. Associated symptoms of gastrointestinal, urological or musculoskeletal origin should be sought. It is also important to take a detailed menstrual history, in particular the frequency and character of vaginal bleeding, any intermenstrual bleeding or vaginal discharge, and their relationship to the pain. Ectopic pregnancy can occur without recognizable amenorrhoea.

A sexual history may be of help, particularly details of any superficial or deep dyspareunia, contraception and sexually transmitted infections (STIs). There may be a family history of gynaecological disorders, for example endometriosis. A cervical cytology history should be recorded.

With chronic pain, there is often value in detailing a family and social history, including marital or relationship problems, pressure at work, financial worries and childhood or adolescent problems, such as sexual abuse. Listening is a centrally important facet of the history-taking, which may in itself be therapeutic for some women. It is useful to ask some open-ended questions such as: ‘What do you think the cause of your pain might be?’ and ‘How is the pain affecting your life?’ to give the woman an opportunity to tell you about aspects of the problem which might not be apparent from a more systematic history.

If the history suggests there is a non-gynaecological component to the pain, referral to the relevant healthcare professional, such as gastroenterologist, urologist, genitourinary medicine physician, physiotherapist, psychologist or psychosexual counsellor, should be considered.

Examination

The examination is most usefully undertaken when there is time to explore the woman’s fears and anxieties. The examiner should be prepared for new information to be revealed at this point. Observation of the woman’s general demeanour is important when assessing the severity of pain. Eye-witness accounts from other health professionals and friends or family may also be helpful. The temperature, pulse and blood pressure should be recorded.

Abdominal examination should include inspection for distension or masses, palpation for tenderness, rebound and guarding, and abdominal auscultation if gastrointestinal obstruction or ileus is suspected. Inspection of the vulva and vagina at speculum examination may reveal abnormal discharge (suggestive of infection) or bleeding. Permission should then be sought to perform a vaginal and rectal examination.

A bimanual examination may reveal uterine or adnexal enlargement suggestive of a pelvic mass, fibroids or an ovarian cyst. Cervical excitation (pain associated with digital displacement of the cervix) is associated with ectopic pregnancy and pelvic infection. Tenderness or pain elicited by bimanual palpation of the pelvic organs themselves is suggestive of an ongoing inflammatory process, which may be infective (e.g. chlamydia) or non-infective (e.g. endometriosis). A fixed immobile uterus suggests multiple adhesions from whatever cause, and nodularity within the uterosacral ligaments (sometimes palpable only by combined rectovaginal examination) can be a feature of endometriosis.

Acute pelvic pain

There are many causes of acute pelvic pain, but the most important gynaecological conditions are ectopic pregnancy, miscarriage, pelvic inflammatory disease and torsion or rupture of ovarian cysts (Box 12.1). If the urine pregnancy test (UPT) is negative, a high vaginal swab, endocervical swab and full blood count should be performed for evidence of infection. All sexually active women below the age of 25 years, who are being examined, should be offered opportunistic screening for Chlamydia. An ultrasound scan is helpful in identifying ovarian cysts, but non-gynaecological causes of pain should not be forgotten.

Box 12.1

Causes of acute pelvic pain

icon01.gif Gynaecological: ectopic pregnancy, miscarriage, acute pelvic infection, ovarian cysts

icon01.gif Gastrointestinal: appendicitis, constipation, diverticular disease, irritable bowel syndrome

icon01.gif Urinary tract: urinary tract infection, calculus

icon01.gif Other causes: musculoskeletal

While the results of investigations are awaited, it is important to continue monitoring the vital signs and to provide analgesia. If the diagnosis is unclear and the pain is not resolving, a diagnostic laparoscopy may be warranted.

The management of miscarriage, pelvic inflammatory disease and ovarian cysts is discussed in the appropriate chapters. An innocent cause of pain is that experienced mid-cycle with ovulation, the so-called ‘mittelschmerz’. This pain is usually sudden in onset, can be quite severe and, if persistent in each cycle, will respond to ovulation suppression with the combined oral contraceptive.

Chronic pelvic pain (CPP)

Healthcare costs associated with CPP are very considerable and do not take into consideration the disability and suffering of the woman and loss of earnings to both the individual and employer. CPP can lead to loss of employment, family and marital discord, divorce, medical misadventures and litigation. Among high-quality studies, the rate of dysmenorrhoea was 16.8–81%, that of dyspareunia was 8–21.8% and that of non-cyclical pain was 2.1–24% worldwide.

The definitions of CPP are numerous but one suitable definition is ‘intermittent or constant pain in the lower abdomen or pelvis of at least 6 months’ duration, not occurring exclusively with menstruation or intercourse and not associated with pregnancy’. A comparison between acute and chronic pelvic pain is shown in Table 12.1.

Table 12.1

Comparison of acute and chronic pelvic pain

Acute

Chronic

Well-defined onset

Ill-defined onset

Short duration

Unpredictable duration

Rest often helpful

Rest usually not helpful

Variable intensity

Persistent

Anxiety common

Depression common

Disease symptom

May not be possible to identify an underlying disease process

The management of CPP is particularly challenging, as there are so many possible causes and contributory factors (Box 12.2). An association with dysmenorrhoea, dyspareunia, irregular menstruation, abnormal vaginal discharge, cyclical pain and infertility, may all be helpful in suggesting an underlying gynaecological problem. Altered bowel habit, excess flatulence or flatus, constipation or diarrhoea, on the other hand, point to a gastrointestinal problem, particularly irritable bowel syndrome. Psychiatric, urological and musculoskeletal causes of chronic pain are further possibilities.

Box 12.2

Differential diagnoses for women with chronic pelvic pain

icon01.gif Gynaecological: endometriosis, adhesions (chronic pelvic infection), adenomyosis, leiomyoma, pelvic congestion syndrome, ovarian cysts

icon01.gif Gastrointestinal: adhesions, appendicitis, constipation, diverticular disease, irritable bowel syndrome

icon01.gif Urinary tract: urinary tract infection, calculus, interstitial cystitis

icon01.gif Skeletal: degenerative joint disease, scoliosis, spondylolisthesis, osteitis pubis

icon01.gif Myofascial: fascitis, nerve entrapment syndrome, hernia

icon01.gif Psychological: somatization, psychosexual dysfunction, depression

icon01.gif Neuropathic: pudendal nerve entrapment, spinal cord neuropathies

Physical and sexual abuse, as well as pelvic pathology such as endometriosis, adhesions and pelvic varices, predispose women to CPP. It is believed that adhesions may be a cause of pain, particularly on organ distension or stretching. Dense vascular adhesions are likely to be a cause of CPP, as dividing them appears to relieve pain. Symptoms suggestive of irritable bowel syndrome or interstitial cystitis are often present in women with CPP. These conditions may be a primary cause or a component of CPP.

Up to 40% of women with CPP, however, do not have an identifiable biological cause, despite extensive investigations. It is therefore important to plan which investigations are necessary, carry them out, and then call a halt to any further investigations, if no pathology is identified. In gynaecology, such investigation often involves a diagnostic laparoscopy. Further management then depends on whether a pathological cause has been identified or not, and this is considered below. Again, there is some overlap between the two groups (Fig. 12.1).

f12-01-9780702054082

FIG. 12.1An example of a management pathway for patients with chronic pelvic pain following laparoscopy.

Endometriosis

See Chapter 13.

Pelvic infection

Chronic pelvic infection is associated with a high incidence of tubal damage, and consequently an increased incidence of ectopic pregnancy, infertility or CPP. It may be due to relapse of infection because of inadequate treatment, reinfection from an untreated partner, post-infection tubal damage or further acquisition of STIs. The severity of the problem is related to the number of episodes of pelvic inflammatory disease and the extent of pelvic adhesions.

Ovarian cysts

The majority of ovarian cysts are benign, particularly those presenting with acute pain. Pain may occur because of torsion, cyst rupture or bleeding occurring into a cyst. Management depends on the presenting clinical situation, but suspected torsion necessitates surgical removal.

Other causes

If investigations are negative and there remains significant diagnostic doubt about whether a pain is gynaecological or not, it may be worth considering a 3-month trial of ovarian suppression with a GnRH analogue. A dramatic reduction of symptoms following suppression with recurrence after treatment suggests a true gynaecological cause, including the possibility of adenomyosis, and there is evidence that hysterectomy will lead to long-term improvement in around three-quarters of this responding group. Many, however, may not wish, or be suitable for such radical surgery, and others will be no better, despite the suppression.

No identifiable pathological cause for the pain

Treating a woman with CPP without a specific diagnosis is particularly difficult because of the uncertainty for both the clinician and woman, and the problems that this then causes in choosing an appropriate therapeutic intervention. The first step has to be that both the clinician and woman accept ‘chronic pelvic pain syndrome’ as a disease entity in its own right and then devise strategies to relieve the physical, psychological and social distress that this causes.

Management options range from psychosocial therapy, analgesia management including use of anticonvulsants like gabapentin, hormonal treatments, antidepressants (like amitriptyline) and complementary therapies, to surgery, including surgical excision of nerves (uterine nerve ablation) and pelvic clearance. Communication with the woman should include sharing of information, honest and realistic discussion of the pros and cons of various investigation and treatment options and the likelihood of there being a beneficial outcome. It may also be helpful to involve the woman’s partner or friend in the decision-making process.

Encouragement to lead as normal a life as possible whilst investigation and treatment are instigated is acknowledged to be very important in the likelihood of making a full recovery. This would include encouraging return to work, exercise, maintaining a healthy diet, avoiding the inappropriate use of analgesia, and looking for alternatives to analgesia where possible. Complementary therapies such as reflexology, homeopathy and acupuncture may be helpful.

The risks of medical misadventure associated with CPP can be minimized by adopting a sympathetic and caring multidisciplinary approach, or by referral to healthcare professionals with a special interest and expertise in managing this condition. A multidisciplinary team approach should ideally include expertise in gastroenterology, neurology, pain management, psychiatry and psychology. Specific psychological approaches to the management of CPP, with input from psychologists and liaison psychiatrists, may be helpful to many women. These approaches include behavioural therapy, cognitive behavioural therapy, group therapy and pharmacological therapy. Pharmacological therapy (e.g. antidepressants and anxiolytics) may be particularly valuable for those individuals who have become secondarily depressed as a consequence of their chronic pain.

Key points

• Acute and chronic pelvic pain have numerous, occasionally overlapping, causes (Boxes 12.1 and 12.2).

• Many women present because they want an explanation for their pain. Often, they already have a theory or a concern about the origin of the pain. These ideas should preferably be discussed in the initial consultation.

• The multifactorial nature of chronic pelvic pain should be discussed and explored from the start. The aim should be to develop a partnership between clinician and patient to plan a management programme.

• Diagnostic laparoscopy has been regarded in the past as the ‘gold standard’ in the diagnosis of chronic pelvic pain. It may be better seen as a second line of investigation if other therapeutic interventions fail. Transvaginal scanning and MRI are useful tests to diagnose adenomyosis.

• Women with cyclical pain should be offered a therapeutic trial using the combined oral contraceptive pill or a GnRH agonist for a period of 3–6 months before having a diagnostic laparoscopy.

• Women with symptoms suggestive of irritable bowel syndrome should be offered a trial of antispasmodics and try amending their diet to control symptoms.

• Women should be offered appropriate analgesia to control their pain, even if no other therapeutic manoeuvres are yet to be initiated. If pain is not adequately controlled, consideration should be given to referral to a pain management team or a specialist pelvic pain clinic.

• While the commonest causes of chronic pelvic pain are endometriosis and chronic pelvic infection, over one-third will have no identifiable pathology. It is important to call a halt to unnecessary investigations: accept the ‘chronic pelvic pain syndrome’ as a disease entity in its own right.