The gold standard for diagnosing or even knowing early sign of pulmonary fibrosis are available is HRCT, high resolution CT scan , where we see a basal predominant bilateral reticulonodular shadows, along with changes of honeycombing and architectural distortion with lot of gradient, which is more and basal predominant, that is classical of UIP pattern, which is the more histopathological variant of this kind of finding is very very important to make radiological diagnosis of UIP because 99% it says that it is idiopathic pulmonary fibrosis, and you can see the UIP pattern in rheumatoid arthritis and scleroderma also. So this is important finding in HRCT and any interstitial thickening, nodular shadows, we can detect in a high resolution CT scan. The initial suspicion when it comes is after having an oxygenation drop in the clinical examination and we see the x-rays which can be ruled out as being normal. Sometimes we can see a reticulonodular saddle and on clinical examination crepits or clubbing and if it is not explained very easily by any other things, then we go for HRCT, where we nearly, unless certain atypical pneumonia or bronchopneumonia, they mimic like that. With certain interstitial lung disease or acute pulmonary fibrosis are there, then the variant of that or LIP’s and other things can be detected in a radiology. But sometimes if it is a Non-UIP or atypical presentations of UIP, like nonspecific interstitial pneumonia and who have a characteristic finding in HRCT, like reverse yellow sign and other things will be there. So basically it is that and 6 minute walk test, pulmonary function test and advanced lung function tests, which reconfirms. Pulmonary function tests in a basic spirometry shows as a restrictive pattern. Sometimes if he is a smoker and associated COPD, they can have a mixed pattern and when we do the advanced lung function, usually the lung volumes are reduced and it is miniature of the normal spirometry and the diffusion limitations will be there. So if you get an echo finding, if an early fibrosis is there, early pulmonary artery hypertension features are seen. 6 minute walk test, can have exercise hypoxia and those things will be there and to conform the diagnosis of connective tissue disorders related ILD’s, we can do AN or Anti-Nuclear Antibody Screening and Rheumatoid Arthritis Factor Screening. So if you find a serological positive and if it is compatible, we can treat without even going for biopsy. Like these are being diagnosed, sometimes we have difficulty, when the serology is negative and when the patient is fit enough and young and we have ruled out any other vasculitis like ANCA and any other infections have been ruled out, we may resort to doing a bronchoscopy to rule out alternate pathologies like tuberculosis or unusual organisms or atypical infections. Along with that, sometimes we do a conventional transbroncial lung biopsy, which is slightly risky with pneumothorax and pathologist not been available, who having the proper lung pathogenesis like UIP and NSIP patterns and the new kid in the block is cryolung biopsy, which is called a cryotransbronchial lung biopsy, where a cryoprobe is used and tissue has been architectural distortion or a big tissue is been found on a biopsy tissue or on a lung biopsy, which a pulmonologist or an interventional pulmonologist can do and most of the centers don’t have at the present and few advanced centers can afford to have a cryobiopsies and the risk of pneumothorax and bleeding are high, and usually these patients are of sick classes will be there and elderly and comorbidities will be there and sometimes risks and benefits of doing the transbronchial lung biopsy has to be seen. The best way or the gold standard way of getting a diagnosis is open lung biopsy, which is usually done by either a wax or an open thoracotomy. Usually surgeons do it and we get a good tissue, but most of these patients have not been fit for undergoing the biopsy and usually whenever we subject the person for a biopsy, we always look at a non invasive way of doing a diagnosis. We will not be able to do it and since we have to follow these guidelines, because there are new treatment modalities which are available and the guidelines keep changing from 2011 to 2015 or 2017 because the treatment modalities are different and it is absolutely a grave disease. In that way the diagnosis of pulmonary fibrosis are being made.