3 The procedure
3.1 The procedure is usually carried out with the patient under conscious sedation, in an outpatient setting. Using endoscopic visualisation, an appropriately sized radiofrequency ablation probe attached to the endoscope is inserted into the oesophagus, and advanced to the target area. Controlled pulses of radiofrequency energy are delivered, which cause thermal ablation of a thin layer of epithelium in the affected areas. A circumferential ablation catheter is usually used for primary treatment, whereas a focal ablation catheter can be used for remaining patches of Barrett's epithelium in any subsequent treatments. Radiofrequency ablation can also be used after doing endoscopic resection to remove larger, superficial abnormal areas. If follow‑up high‑definition endoscopy and re‑biopsy show residual Barrett's changes, repeat treatment can be done using radiofrequency ablation.