To the Editor: So a large proportion of women experience pelvic pain, often over years. What’s new? Of course they do. Pitts and colleagues1 fail to mention that virtually every normal, physiological event that occurs within a woman’s pelvis is associated with pain. Clearly, such pains vary in duration and intensity and are associated with events such as ovulation, menstruation, pregnancy, labour and childbirth. We men have it easy by comparison. But to conclude by saying that “only about a third of women who experience chronic pelvic pain seek advice from a health professional” gives the impression the authors are trying to medicalise yet another essentially normal event.

One can get into long, philosophical discussions as to why such normal events should be so painful, but it remains a fact. I have spent my career urging general practitioners and fellow specialists to avoid surgery and “silver bullets” in most cases of pelvic pain and follow a conservative approach.2 It would have been more helpful if the authors had gone on to discuss what type of pain is suffered by what type of woman and who is treated by what type of doctor. This truly would have assisted in determining who would benefit from the attention of a health professional and who would not.

To the Editor: We read the recent article by Pitts and colleagues1 with interest, given the rising trend of diagnosed chronic pelvic pain (CPP) in Australian women. The article identified three types of CPP, but did not differentiate pain into the two major categories of nociceptive (visceral and somatic) and neuropathic. In pain management settings it is considered essential, where possible, to make this differentiation, as it significantly alters management strategies, particularly in relation to medication. While the true incidence of neuropathic pain is unknown, it is believed to be underdiagnosed and inadequately treated. A 2008 French study based on a nationwide postal survey revealed a 6.9% prevalence of neuropathic pain in the general population, with 5.1% of respondents reporting pain levels as moderate to severe.2

Neuropathic pain results from damage to the nervous system. Specifically, this can be from damage to, or pathological changes in, the axons of peripheral nerves or from damage to the central nervous system, probably as a result of deafferentation. This is the process whereby neurones in the central nervous system lose their accustomed afferent input, either from a peripheral nerve or from an ascending sensory tract. Furthermore, neuropathic pain can and does cross neuroanatomical boundaries, often presenting viscerally as referred pain and eliciting pain descriptors such as burning, shooting, stabbing, and searing. For this reason, CPP is often wrongly assumed to be visceral in origin.3 In such cases, awareness that CPP may in fact be neuropathic may avoid inappropriate surgical interventions. Moreover, an association between CPP and neuropathy has been demonstrated in studies of sacral nerve and percutaneous tibial nerve stimulation in women presenting with CPP.4,5

Differential diagnosis of pain of neuropathic origin has been shown to be pertinent for the accurate implementation of pain management strategies.6 Therefore, we suggest that future studies on the epidemiology and/or prevalence of pain include tools to determine the proportion of pain of neuropathic, nociceptive and mixed origin. There are a number of tools available, including questionnaires such as painDETECT, DN4 (Douleur Neuropathique en 4), LANSS (Leeds Assessment of Neuropathic Symptoms and Signs) and NPS (Neuropathic Pain Scale). Some of these, such as the self-assessed LANSS (S-LANSS), do not require clinical examination and thus can be worked into population-based questionnaires. The ability to identify neuropathic pain should lead to individualised treatment, resulting in improved pain control for patients with CPP.

In reply: We are pleased to see our article about chronic pelvic pain in Australian women has provoked interest.1 Black’s suggestion that virtually every normal physiological event that occurs within a woman’s pelvis is associated with pain is surprising, and not supported by our evidence. Of the women in our sample, 23% were totally pain free, and most of the chronic pelvic pain reported was mild. A parallel study showed that men also suffered chronic pelvic pain — a smaller proportion than women, but still significant.2 We are not medicalising normal events; rather, we are alerting general practitioners to the normal range of pelvic pain experience to help them assess its clinical significance. A GP who says to a female patient “it’s normal, love, just grin and bear it” denies the psychosocial complexity of her experience.

Vivian and Barnard suggest we might have differentiated between two major types of pain, nociceptive and neuropathic. It would not be practical to collect this information in a broad survey on sexual and reproductive health. Certainly, a study of the prevalence of neuropathic pain in the Australian population that mirrors recent studies overseas would be informative. However, our study concerned pelvic pain only. The pelvis is not a common site for neuropathic pain.3