THE CONCERN raised over cervical screening as a result of the problems at St George's hospital highlights the inexact nature of medical science, where different doctors can often provide different treatments to patients with identical disorders.
Although medical experts can be in broad agreement over how to diagnose or treat a potentially fatal illness such as cervical cancer they often disagree on details of clinical practice.
In the case of cervical screening, there are several points in the chain of investigation where doctors have to rely on their subjective assessment of the problem rather than the objective facts.
Cells scraped from the lining of the cervix during a smear are first analysed under a microscope and one laboratory scientist may differ from another in the assessment of the abnormal cells present in a sample.
However, it was the second stage of the screening service at St George's, when women with abnormal smears were recalled for a more detailed colposcopy examination, that the clinical judgement of one doctor appeared to be at odds with the "best clinical practice" as defined by other experts.
The roots of the problem result - at least in part - from the piecemeal way cervical screening has developed in Britain with different clinical centres adopting their own particular approaches.
It was only two years ago that a set of national guidelines were drawn up to try to establish a common code of practice that all screening centres could follow. …