About 15 per cent of women of reproductive age suffer from pelvic pain. Many are forced to take several days off sick every month; it is estimated that the National Health Service spends around pounds 160m a year on tests, many of them inconclusive, to find the root of the problem.
There is a growing interest in pelvic pain, and although research indicates it may be more common than back pain, there is ignorance on the subject among the public and a general lack of interest in medical circles. GPs often dismiss it as period pain, to be endured.
Chronic pelvic pain is notoriously difficult to diagnose and many women find themselves ping-ponged from one specialist to another with little or no diagnosis, let alone remedy, in sight. Few gynaecologists will counsel a woman on how to deal with her pain.
"The common story you hear is of someone who goes to her GP, year after year, before she is taken seriously", says Dr Jane Moore, a gynaecologist and Searle Training Fellow in Pelvic Pain Studies at Oxford's John Radcliffe Hospital. "Then she has a tale of different diagnoses given to her before, eventually, someone alights on the correct diagnosis and she actually gets some relief."
Over the past eight years, since the birth of her second daughter, Mrs Eversfield has been in and out of hospital, seen six gynaecologists and has had a clutch of diagnoses from endometriosis to an over-production of progesterone. She has had a laparoscopy - an exploratory operation done under general anaesthetic - and has done the round of hormones, painkillers, anti-inflammatory medication, even Prozac. She is about to undergo special physiotherapy.
"I felt I was being passed about from anyone to anyone," says Mrs Eversfield, who works as a chef. "I could cope with three or four days out of every month, but for two weeks to be taken out of every month, when you've got to go to work and manage your children, is not acceptable. Pelvic pain is very draining. I don't think anyone realises how it can affect you."
Now, Mrs Eversfield attends the only multidisciplinary clinic in Britain for pelvic pain, at Leicester General Hospital, one of a few centres which offer psychological treatment and pain coping strategies, as well as surgery and drug therapy.
The pain can severely affect a woman's life; she may have to take time off work and it can make sex so painful that many women with pelvic pain rarely, if ever, sleep with their partners. "The emotional cost within relationships is severe. Pelvic pain can wreck marriages and doctors in general aren't good at hearing that," says Dr Moore.
Pelvic pain is defined as any pain in the lower abdomen or pelvis that has lasted for six months or longer, and is not linked with menstruation or sexual intercourse. It is difficult to diagnose because it could be a sign of conditions associated with any of the organs in the abdomen (the womb, ovaries and vulva; gut and bowel; bladder or appendix; the muscles, nerves or bones), even the abdominal cavity itself. The problem is compounded by the fact that hospital consultants specialise in one discipline, so that a gynaecologist will have little interest in any adjacent organs.
Endometriosis, where the lining of the womb grows outside the uterus and bleeds every month, is the most common cause of pelvic pain. Of 100 women with pelvic pain, between 40 and 60 will have endometriosis. A rarer condition is adenomyosis, a form of endometriosis where the lining of the womb invades the womb itself, bleeding into the uterine muscle.
Then there is irritable bowel syndrome (IBS), which affects one in five young women. One study has shown that half the women referred to a gynaecological clinic for pelvic pain have symptoms of IBS. Adhesions, scarring from infections or surgery, are another cause of pain, as is interstitial or chronic cystitis, an inflammation of the bladder wall, once believed rare, but now thought to be quite common.
Pelvic inflammatory disease, often triggered by one of the most common sexually transmitted diseases, chlamydia, can cause excruciating pain, as can a pelvis damaged by childbirth, or muscles and nerves trapped in scar tissue after a Caesarean.
Consultations between women with pelvic pain and their gynaecologists can be miserable affairs. Dr William Stones, a consultant gynaecologist at Southampton General Hospital, has conducted a study of women referred by GPs to gynaecologists for chronic pelvic pain, and found that these considerations were often very negative.
"Women go along not expecting the doctor to achieve much, and conversely the doctor doesn't expect to achieve very much either."
Most women will undergo a laparoscopy, whereby needle-thin instruments and a fibre optic tube are inserted into the pelvis through tiny incisions, and the abdomen is viewed by the specialist. Frustratingly, this will not always pinpoint the cause of the pain. Eight out of 10 women undergoing a laparoscopy for pelvic pain turn out to have a "normal" pelvis.
"A lot of women with pelvic pain don't have any obvious abnormality when you do a laparoscopy, and at least half of women with endometriosis don't have pain," explains Mr Philip Reginald, a consultant gynaecologist at Wexham Park Hospital, Slough.
To make absolutely certain the abnormal tissue on the screen is the cause of the pain, Mr Reginald has pioneered the use of "conscious pain mapping", a practice increasingly common in the US. This a laparoscopy done under local, rather than general, anaesthetic, so the woman can give the doctor instant feedback.
Tweaking the viscera sounds unbearably painful, but Mr Reginald has carried out the operation on 30 women and not one asked him to abandon the procedure. Mr Reginald is one of a handful of gynaecologists practicing this technique, and it allows for accurate diagnosis.
Professor Richard Beard, a consultant gynaecologist at Northwick Park Hospital, Harrow, and Britain's leading specialist in pelvic pain, has suggested that pelvic congestion - chronic dilation of the pelvic veins - leads to a build-up of blood around the pelvis and consequent pain. Professor Beard believes the condition, mainly in women in their reproductive years, is caused by poorly functioning ovaries, which is linked to stress. Treatment is with hormones to suppress ovarian activity, and a course of stress and pain management.
When nothing else works, a gynaecologist will reluctantly suggest a hysterectomy. Adenomyosis, for instance, can be diagnosed only by examining the womb after removal. For three-quarters of women a hysterectomy does the trick, but a quarter are still left with their pain.
The National Endometriosis Society, 50 Westminster Palace Gardens, 1-7 Artillery Row, London, SWAP 1RL; call 0171-222 2776