Obtaining tissue from the mediastinum: endoscopic ultrasound guided transoesophageal biopsy

Endoluminal or endoscopic ultrasound (EUS) was first attempted in 1957 by Wild and Reid who placed a mechanical ultrasound transducer in the rectum.1 It was not until 1975 that the upper gastrointestinal tract was examined when Rasmussenet al 2 measured the stomach wall thickness with a 6 MHz transducer passed through the biopsy channel of a gastroscope. In the 1980s, with the development of a dedicated endoscope incorporating a mechanical ultrasound transducer, EUS became important in clinical practice. Accurate local and nodal staging of oesophageal, gastric, and pancreatic tumours3-6 and assessment of stone disease in the biliary tract7 established EUS in the investigation of gastrointestinal disease. The accurate detection of mediastinal lymph nodes in oesophageal cancer had obvious implications for patients with lung cancer, and the role of EUS in lung cancer was first described in Japan in 1988.8 Further work confirmed the superior accuracy of EUS in the nodal staging of lung cancer compared with computed tomographic (CT) scanning,9 although EUS is not yet used routinely in the preoperative staging of lung cancer in the UK.

Further technical advancement led to the development of the linear EUS probe. This allows passage of a needle down the biopsy channel of the endoscope, through the wall of the gastrointestinal tract, and into adjacent structures such as lymph nodes. The orientation of the ultrasound beam, parallel rather than perpendicular to the long axis of the endoscope, allows continuous ultrasound monitoring of the …