Investigating uncertainty

Ben Hoban is a GP in Exeter. He is LinkedIn

There comes a point in many consultations when, having listened sympathetically, asked insightful questions, and established the significance of someone’s symptoms to them, we recognise that it is not yet possible to reassure, treat, or advise them with confidence. There is still more to be done, and sometimes the next step is to gather further information through various investigations. This has always been part of a doctor’s repertoire, although the frequency with which patients are investigated in general practice is rising, and the need to deal with large numbers of results at the end of a long working day is recognised as part of the reason so many GPs find it difficult to keep going.¹

The additional information obtained from these tests can be helpful in making or excluding a specific diagnosis, although more often, it simply adds weight to one side of the scales or the other: probably okay versus probably not. This naturally relies on carrying out an appropriate set of investigations in the first place, which in turn depends on knowing what we’re looking for, and sometimes we don’t. There is therefore a danger that we end up investigating non-specific symptoms, not in order to pursue relevant lines of inquiry, but simply on the basis of which tests are readily available to us, producing results which may feel meaningful but are impossible to interpret.

It is easy for both doctors and patients to gloss over this need to interpret results. Although we tend to think of them as either normal or abnormal, they simply represent a one-off measurement of some physiological variable. Even something as clear-cut as a pregnancy test can be negative today and positive tomorrow based on small changes in the level of circulating hormones, or vice versa. In classifying a result either way, we are simply holding it up to a fixed point of reference and seeing which side it falls on. This point in theory represents what we would expect if our patient were healthy; in practice, we use instead a statistically defined reference range covering 95% of the population, which isn’t necessarily the same thing.²

Talking about positive and negative results is certainly a useful short-hand, although it also requires us to consider false positives and false negatives, artefacts of our need to dichotomise continuous variables. It is more meaningful to think instead about the pre-test and post-test probability of a specific condition, taking into account both its background prevalence and the impact of a given result on our chance of having it. There is always a starting position which a test result modifies, and “test” here includes even such simple things as a specific question or examination finding. It is not that investigations get it wrong, rather that we expect too much of them, and there are certainly times when a diagnosis is either so likely or so unlikely to begin with that further investigations will make no difference to our clinical management.

This over-valuing of tests perhaps reflects an underlying belief in biomedical certainty, in the idea that truth is hidden away within us, waiting to be discovered by objective scientific means. The alternative view, of diagnosis as a fabric woven together by a patient and their doctor from the warp and weft of life, is less intuitively appealing, and certainly less easy to articulate, although it resonates more deeply with the experience of many.³

Why then, when medical investigation is such a fraught business, do we pursue it so relentlessly? Perhaps it is a loaded question, although a reasonable answer might start by acknowledging that general practice is both more complex and more fragmented than in the past, while our expectations of medicine are higher. The burden of uncertainty in any consultation is therefore greater, and doctor and patient may have less experience of sharing it and less inclination to try. Higher levels of investigation have been linked with a lower tolerance of uncertainty, but ought they to go together?⁴ This is surely what it all comes down to: does more investigation necessarily provide us with more certainty? The short answer appears to be that it does not.⁵ Our position is therefore not dissimilar to that of someone washing their hands once to clean them, and then washing them again just to make sure: the more we do to pursue certainty, the less certain we become.

The use of investigations in general practice is therefore clearly about more than just obtaining further information to enable patient care. Indeed, just like compulsive hand-washing, it starts to feel like a maladaptive behaviour intended to help us feel in control when we are at a loss, but having the opposite effect. We try to validate someone’s concerns but leave them feeling disbelieved when their tests come back normal. We hope for reassurance and get instead borderline results and incidental findings, leading to a cascade of further investigations in which their original concerns are soon forgotten.^6,7 We are careful to document consent to treatment, but how often do we counsel people about the potential harmful effects of investigation?⁸

If we accept that over-investigation is a problem, the solution is not simply to investigate less, but to consider rather how best to approach the underlying issues. We can never know everything, but we only need to understand enough to make the decisions required by our patient’s problem. Sometimes the answer is not to collect more data, but to think more clearly about the questions we are trying to answer, to make full use of the information we have already, and to share the burden of decision-making with the other person in the room. Uncertainty is not some invisible residue to be scrubbed off our skin; we are better off accepting it and learning to shake hands again without fear of contamination.⁹ In order to keep going, we do not need to be in control so much as know that we are doing our job as well as circumstances allow, and if we sometimes feel at a loss, we may serve our patients better by acknowledging it and deciding together what to do than by simply arranging more investigations.¹⁰

References

1. Watson J, Burrell A, Duncan P, Bennett-Britton I, Hodgson S, Merriel SW, Waqar S, Whiting PF; Primary care Academic CollaboraTive. Exploration of reasons for primary care testing (the Why Test study): a UK-wide audit using the Primary care Academic CollaboraTive. Br J Gen Pract. 2024 Feb 29;74(740):e133-e140. doi: 10.3399/BJGP.2023.0191. PMID: 37783511; PMCID: PMC10562996.
2. Nadav Rappoport, Hyojung Paik, Boris Oskotsky, Ruth Tor, Elad Ziv, Noah Zaitlen, Atul J Butte, Comparing Ethnicity-Specific Reference Intervals for Clinical Laboratory Tests from EHR Data, The Journal of Applied Laboratory Medicine, Volume 3, Issue 3, 1 November 2018, Pages 366–377, doi: 10.1373/jalm.2018.026492
3. Sophie Park and Martina Ann Kelly, Hermeneutic approaches in complex multimorbidity, included in Finding Meaning in Healthcare: Looking Through the Hermeneutic Window, edited by Rupal Shah and Robert Clarke, Routledge, 2025
4. Alam, R., Cheraghi-Sohi, S., Panagioti, M. et al.Managing diagnostic uncertainty in primary care: a systematic critical review. BMC Fam Pract 18, 79 (2017). doi: 10.1186/s12875-017-0650-0
5. Kevin Barraclough, Jenny du Toit, Jeremy Budd, Joseph E. Raine, Kate Williams and Jonathan Bonser, Avoiding Errors in General Practice, Wiley-Blackwell, 2013
6. Sullivan J W, Muntinga T, Grigg S, Ioannidis J P A. Prevalence and outcomes of incidental imaging findings: umbrella review BMJ 2018; 361 :k2387 doi:10.1136/bmj.k2387
7. Lilford RJ, Bentham L, Girling A, Litchfield I, Lancashire R, Armstrong D, et al. Birmingham and Lambeth Liver Evaluation Testing Strategies (BALLETS): a prospective cohort study. Health Technol Assess 2013;17(28), DOI: 10.3310/hta17280
8. Hofmann B, Welch HG. New diagnostic tests: more harm than good. BMJ. 2017 Jul 18;358:j3314. doi: 10.1136/bmj.j3314. PMID: 28720607.
9. Jorge L Polo-Sabau, Shaking hands again, BJGP Life, 17 September 2025
10. Owen-Boukra E, Burford B, Cohen T, Duddy C, Dunn H, Fadia V, Goodman C, Henry C, Lamb EI, Ogden M, Rapley T, Rees EL, Roberts NW, Royer-Gray E, Vance G, Wong G, Park S. General practitioner workforce sustainability to maximise effective and equitable patient care: a realist review. Br J Gen Pract. 2025 Sep 29:BJGP.2025.0061. doi: 10.3399/BJGP.2025.0061. Epub ahead of print. PMID: 41022521.

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