Both endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are carried out with the patient under sedation or general anaesthesia. Using endoscopic visualisation, the submucosa is injected with saline to help lift the lesion. This fluid may contain pigment to help define the lesion, and adrenaline to reduce bleeding. In EMR, lesions are usually removed piecemeal with a snare. In ESD, submucosal dissection is performed with an electrocautery knife, parallel to the muscle layer, aiming to remove the lesion intact and with clear margins. A transparent hood may be used to retract the already dissected part of the lesion out of the visual field. Haemostasis is achieved by electrocautery. Endoscopic clips may be used for larger vessels or to manage perforation.