It is unlikely to be controversial for me to suggest that pain is not merely a product of sensory stimulation (please excuse that rather clunky double-negative). I have previously mentioned the annals of Henry Beecher, wherein soldiers during World War II were observed to decline analgesia despite serious battle wounds or pending medical interventions1. More colloquially, I have vivid memories of my younger self coming off the football pitch at half-time and only then noticing a deep cut to the shin or blood pouring from the knee. The Cartesian premise of the brain simply representing a “bell on the end of the rope”, which rings when the rope is tugged via a hammer-blow to the hand, struggles to mould around these examples2. However, these examples could be said to just reflect an attentional or motivational conflict. The soldiers had more pressing or life-threatening issues on their mind, and I was absorbed by the competition of sport to notice.
We also know that the influence on pain processing can precede the injury as well. Placebo-focused pain research has shown us that an inert analgesia can reduce the experience of the painful stimulation that follows3. What’s more, the manipulation of expectation doesn’t even need to be physical via the application of a cream or IV. Just by telling people that the stimulation is likely to be more (or less) painful you can alter their very experience to a stable noxious (read: potentially harmful) stimulus4. This has been observed in self-reported pain ratings, as well as underlying neural activation in the brain5. Tellingly, a large focus of this research has focused on the potency of prediction errors. A recent paper published out of the University of Manchester encapsulated prediction errors with great articulation (in my opinion)6. The researchers wrote:
“Imagine having a calm picnic in the garden, when you are suddenly stung by a wasp. Although you had no reason to expect any pain before being stung, you immediately feel searing pain. The discrepancy between prior pain expectations, which in this example were null, and the sensory evidence, here the bodily response to the venom in the sting, is termed pain prediction error (PE)”– Hird et al., page 2, 2019.
The paper provides critical nuance for those who are interested in prediction errors, and I recommend reading it in full if you wish to learn more of this phenomenon. But, for the purpose of this blog, I’d like to keep that quote in mind while I talk about my own publication, examining the gynaecological procedure of hysteroscopy7.
The British Journal of Anaesthesia recently published our paper representing work over several years between the Royal Berkshire Hospital and University of Reading, empirically investigating reports of intense pain being experienced during hysteroscopy. Importantly, at the onset, this procedure was advertised as being pain-free or associated with minimal pain, which can be sufficiently managed via over-the-counter analgesics. The movement away from sedation was advocated via technological improvements to surgical equipment, and supported by findings of substantial reductions in financial cost and healthcare provider resources8. I feel it is pertinent to mention the instigation for this work was led via gynaecologists in the hospital itself, who were personally concerned by experiences with some of their patients, and insisted upon the collection of data to quantify the extent of this problem. At this point, I was entirely naive towards hysteroscopy. I found the results truly alarming, and since then, have learned a lot about the plight of patients nationwide who have suffered from this procedure. I wish to share our results for them, as well as all women who will one day undergo hysteroscopy. Please read the paper for a full recount, as I am not describing the full study here, but I want to share two interesting findings in particular.
For this paper, we analysed the data of 804 hysteroscopy patients who underwent hysteroscopy, focusing on their pain ratings and the quantity of local anaesthetic administered. Our research questions focused on whether patients reported pain from their procedure and whether local anaesthetic was used appropriately to manage pain. As mentioned, our analysis yielded surprising results. Firstly, and unequivocally, the evidence suggested that hysteroscopy is not pain-free. In fact, it is often associated with pain, with a substantial subset of patients rating severe pain. Specifically, 7.8% reported no pain, with 17.6% reporting pain between 7-10 (on a 0-10 scale). Pharmacological pain management within this protocol is limited to the application of 0-3 units of local anaesthetic. We identified that very few patients received the maximal dose of anaesthetic (1.9%) and many patients received none at all (37.7%). Within those who received a non-maximal dose, a large proportion reported severe pain, between 7-10. Two clear conclusions from this data are that hysteroscopy is rarely pain-free, and that pain management represents a clear practical target for improving the outcomes of hysteroscopy.
Personally, I have noted how surprised, absorbed and passionate I have become during my time involved in this project. I have been blown away with the passion and drive of campaigns and charities trying to raise public awareness of this clinical issue. I have been emotionally impacted by the personal reports of women who have been mistreated or traumatised during poor hysteroscopies. But I have also been caught off guard with how little empirical investigation has been conducted alongside this. To my knowledge, our work represents the first published empirical project providing support for the presence of pain in hysteroscopy. Something which has been greatly missing to further the arguments for reviewing the protocols underlying the procedure. One thing I feel I can say, with empirical backing, is that hysteroscopy should be advertised alongside warnings for the potential for pain and all women should be given honest and accurate information, to enable them to make fully informed choices. This is not just pertinent for morality, ethics and medical professionalism. It also relates to the wasp at the picnic…
Scientifically, we know that pain is malleable and personal. Expectations are not just a pre-clinical consideration. Expectations have bearing on the experience of pain in the future. The dangers of advertising hysteroscopy as a mildly painful procedure are many. Firstly, this stands to put women off engaging with a very useful diagnostic test for the identification of serious medical conditions, such as ovarian cancer or endometriosis. But secondly, it is highly plausible that the resulting prediction error stands to make the experience even more painful than if patients were appropriately warned. If hysteroscopy is marketed to be a tranquil picnic, it is crucial that the risk of wasp sting is non-existent (or at least rare). Our findings suggest the picnic is only tranquil 7% of the time. This, at the very least, must be changed.
It is always important to try and find the positive story, even within stories that are predominantly negative, such as this. My viewpoint is that our project represents the full power of collaborations across disciplines and perspectives. When clinicians, patients, scientists and government work together, we can achieve great things. This project would not have been possible without empathic and concerned clinicians wishing to understand why so many patients in their care were suffering. My research team were able to appropriately analyse the results to unearth a cohesive and congruent narrative, founded in empirical data. The insight and advice from the Campaign Against Painful Hysteroscopy brought me up to speed with the scope of the problem. And the patients who have suffered from this procedure ensured I appropriately understood the humanity and reality of the issue.
I have tried (and likely failed) to keep this brief and concise, as I know that life can be a busy place. I have also tried to avoid jargon and scientific wish-wash along the way. I am aware that my article will not be available to all, and want to ensure that the message reaches those who need to read it. As with all my research, please feel free to contact me if you wish to ask me any questions or clarifications. My blog gives me an opportunity to provide some of my opinions alongside the empirical evidence that we report. I know that this is an incredibly delicate subject for some, and many have been adversely impacted by hysteroscopy. If I have offended anyone with my description of the problem or my findings, accept my apologies. I wish the campaigners the best of luck with their pursuit of change, and hope that our science provides some weaponry with which to arm your fight.
Stay healthy & stay safe
1) Beecher, H.K. Relationship of significance of wound to pain experienced. JAMA, 161(17),1609-1613.
2) Melzack R, Katz J. The Gate Control Theory: Reaching for the Brain. In: Craig KD, Hadjistavropoulos T. Pain: psychological perspectives. Lawrence Erlbaum Associates, Publishers; 2004.
3) Wager, T. D. (2004). Placebo-Induced Changes in fMRI in the Anticipation and Experience of Pain. Science. 303, 1162–1167.
4) Tracey, I. (2010). Getting the pain you expect: mechanisms of placebo, nocebo and reappraisal effects in humans. Nature Medicine. 16, 1277–1283.
5) Büchel, C., Geuter, S., Sprenger, C. & Eippert, F. (2014). Placebo analgesia: A predictive coding perspective. Neuron. 81, 1223–1239.
6) Hird, E.J., Charalambous, C., El-Deredy, W, Jones, A.K.P., Talmi, D. (2019). Boundary effects of expectation in human pain perception. Scientific Reports. 9, 9443.
7) Harrison, R., Kuteesa, W., Kapila, A., Little, M., Gandhi, W., Ravindran, D., van Reekum, C.M., Salomons, T.V. (In Press). Pain-free day surgery? Evaluating pain and pain assessment during hysteroscopy. British Journal of Anaesthesia.
8) Clark TJ, Middleton LJ, Cooper NA, Diwakar L, Denny E, Smith P, Gennard L, Stobert L, Roberts TE, Cheed V, Bingham T, Jowett S, Brettell E, Connor M, Jones SE, Daniels JP. (2015). A randomised controlled trial of Outpatient versus inpatient Polyp Treatment (OPT) for abnormal uterine bleeding. Health Technol. Assess. 19, 1–194.