What initial investigations should be conducted for a patient presenting with haemoptysis?

Initial investigations for a patient presenting with haemoptysis should include:

• A chest X-ray to identify any underlying pathology such as infection, malignancy, or other lung diseases.

• Full blood count to detect anaemia or polycythaemia which may contribute to or result from haemoptysis.

• Three respiratory sputum samples, preferably spontaneously produced deep cough samples including at least one early morning sample, for microscopy and culture to identify infections such as tuberculosis.

• Rapid nucleic acid amplification tests for Mycobacterium tuberculosis complex on sputum samples if tuberculosis is suspected, especially in patients with risk factors or where rapid diagnosis would alter management.

• Consider CT thorax if chest X-ray findings are abnormal or if further detailed imaging is required to assess the cause of haemoptysis.

Additional investigations such as ECG, serum natriuretic peptides, echocardiogram, and sputum culture may be considered based on clinical suspicion of cardiac disease or other lung conditions.