fistula       
noun [ C ]  medical specialized uk/ˈfɪs.tʃə.lə/ us/ˈfɪs.tʃə.lə/
 瘘,瘘管
an abnormal opening or passage from one organ to another or from an organ to the skin surface
  an anal fistula 肛瘘 
 Gas in the bladder may be related to a fistula between the bladder and the colon. 膀胱气肿可能与膀胱和结肠之间形成瘘管有关。