Having advanced esophageal carcinoma; After esophageal surgery or endoscopic treatment ; Known esophageal radiotherapy or chemotherapy ; Esophageal stenosis; Acute bleeding; A known allergy to iodine; Coagulopathy (prothrombin time <50% of control, partial thromboplastin time >50 seconds); Having food retention; Severe hepatic ,renal, cardiovascular or metabolic dysfunction ; Being pregnant or lactating;