Percutaneous transthoracic lung biopsy is thought to have been developed by Leyden in 1883 in order to diagnose pneumonia. The technique was extended to the diagnosis of cancer from the 1930s onwards, but at that time there was a significant complication rate, primarily associated with the use of large bore needles. The more widespread use of the technique in the 1960s and 1970s was heralded by the development of high resolution image intensification and improved cytological techniques, which permitted the use of smaller needles and reduced complications. One hundred and twenty years after its inception, percutaneous lung biopsy is now a generally accepted and widely used method of establishing the aetiology of lung masses.

Despite its usefulness, the procedure is not without its morbidity and rarely mortality. It was one of these rare deaths that prompted a search for current standards of good practice. A survey published in 2002 by Richardson et al,¹ in which all known centres performing lung biopsy in the United Kingdom were invited to participate, showed that practice varied greatly across the country. Some centres reported undertaking as few as three biopsies a year and others over 200. There appeared to be a general lack of consensus about most aspects of the procedure, and this was reflected in confusion over whether patients needed to be admitted overnight, the range of prebiopsy tests required, and the timing of follow up chest radiographs. This was the first national study of percutaneous lung biopsy in the United Kingdom and it concluded that national guidelines were needed to ensure consistency of standards. The guidelines published in Thorax this month have been with this aim.

Any guidelines will generate objections to at least some of their recommendations and for that reason the current paper has been reviewed by various groups and societies who can be regarded has having an interest in the topic. As the title of the article suggests, they are intended to offer guidance based on evidence to those with experience and to help those who have a more limited practice.

One of the main developments in the management of lung cancer has been the formalisation of the multidisciplinary team, which is now the cornerstone of clinical practice in this disease. These guidelines encourage the use of the same concept in the process of deciding in whom and how to biopsy lung lesions. The term “multidisciplinary meeting” (MDM) has been used partly to avoid confusion with the cancer group, but also to make clear that the decision making group is not as large and is less rigid in its structure. Despite this the MDM, consisting of at least a radiologist and a respiratory physician, or a clinician with an interest in respiratory medicine, is recommended as the way in which decisions about whether to undertake a lung biopsy should be organised. This practice should ensure a proper preprocedure assessment, both of the need for biopsy and of patient suitability.

There is controversy over the role of percutaneous biopsy in the diagnosis of potentially resectable lung masses in patients considered operable. Some units prefer to proceed straight to surgery in this situation, arguing that a percutaneous biopsy rarely changes the need for surgery in these patients. Others feel that patients should have a histologically confirmed malignancy before proceeding to surgery, to avoid doing unnecessary operations in those who have benign disease. This difficult issue has not been addressed in these guidelines, but it serves to emphasise the importance of multidisciplinary decision making before biopsy.

These guidelines do not seek to be prescriptive. Some operators may have a preference for a particular type of needle or means of imaging. This often depends on the local circumstances or external factors. Where evidence is available, the most appropriate method has been advised. For instance, if a lesion is suspected to be benign the yield in these circumstances is favoured by the use of a cutting needle. However, in certain centres where there is a confident cytopathologist, fine needle aspiration may achieve similar accuracy of sampling for benign lesions. Similarly, having a cytologist present at the time of biopsy to review the sample reduces morbidity and increases yield but has significant resource implications.

Recently there has been a move to do lung biopsies as day case procedures, and this practice has been implemented successfully in many centres. Published reports indicate that this can lead to better use of hospital beds without an increase in the risk to the patients if they are selected appropriately. It does, however, depend on instructing the patient carefully and giving written and verbal instructions should their condition deteriorate on leaving hospital.

It is worth remembering that guidelines are only as good as the evidence they are based upon. One of the main problems in establishing procedural guidelines is the lack of grade A, or even grade B, evidence to support particular practices. The published morbidity and the mortality rates associated with percutaneous lung biopsy vary widely. The quoted pneumothorax rate post-biopsy ranges from 0% to 61%, although in the UK survey¹ the range was between 14% and 20%. Clearly practitioners should aspire to the lowest figure, but centres should audit their own practice in order to inform patients of local complication rates.

Furthermore, to ensure that normal clotting studies are available before a biopsy would seem prudent, but no randomised controlled trials have ever been done to assess this. Similarly the safe cut off values for FEV₁ are difficult to establish but for obvious ethical reasons no grade A evidence exists. In cases where the evidence base is weak, common sense and consensus have been used. Additionally good practice has been derived in some areas by looking at the advice given by other groups such as the BTS guidelines on diagnostic flexible bronchoscopy.²

In conclusion, although a few of the recommendations may go against some practitioners’ cherished practices, they are intended to offer food for thought for the experienced and guidance for the less experienced—they are for the obedience of fools and the guidance of wise men.