Invasive biopsy techniques
Endoscopy and biopsy techniques are essential tools in many respiratory diseases when simpler clinical and laboratory methods of investigation have failed to yield a diagnosis. The results of biopsies are heavily dependent upon the quality of the pathological and microbiological examinations.
The most important endoscopic method in respiratory medicine is bronchoscopy; for diagnostic purposes, this is almost exclusively performed with a flexible bronchoscope using video-assisted imaging, usually under local anaesthetic (figure 4). Bronchoscopy is associated with very few complications. The procedure not only allows inspection and sampling of the airways, but also facilitates transbronchial needle aspiration (TBNA) from the lymph nodes, sampling material from peripheral lesions with special catheters and brushes, or transbronchial lung biopsy (TBLB) by forceps, often under guidance of EBUS or fluoroscopy. A more elaborate technique to guide the bronchoscopist to small lesions is electromagnetic navigation.
Bronchoalveolar lavage (BAL) involves the instillation of saline via a bronchoscope in order to collect specimens for cytological or microbiological investigation. It is used mainly in interstitial lung diseases or lower respiratory tract infections, as material can easily be obtained from the periphery of the lung.
Autofluorescence and narrow-band imaging
Autofluorescence or narrowband imaging may be helpful in the detection of precancerous lesions and early cancers located in the bronchial tree.
Percutaneous needle biopsy
Percutaneous (or transthoracic) needle biopsy is mainly performed to investigate peripheral lung lesions when bronchoscopy is negative. It is performed with the guidance of either fluoroscopy or, preferably, CT. When lesions are adjacent to the chest wall, ultrasound guidance can also be used.
Thoracentesis and pleuroscopy (medical thoracoscopy)
Thoracentesis (pleural fluid aspiration or ‘tap’) is a frequently performed procedure in pleural effusions, preferably used under ultrasound guidance, at least when the effusion is small. Additional biopsy procedures, such as closed-needle biopsy of the pleura or pleuroscopy (medical thoracoscopy), may be necessary to confirm or exclude malignant or tuberculous causes of an effusion.
Surgical investigative methods include mediastinoscopy and the minimally invasive technique of video-assisted thoracic surgery (VATS). Mediastinoscopy is used for biopsy of mediastinal lymph nodes (if TBNA is negative). VATS has almost completely replaced the use of open surgery for diagnostic purposes in intrathoracic lesions (including interstitial lung disease), in which the aetiology remains uncertain after performance of the above less invasive procedures.