Filling defect

A filling defect is a general term used to refer to any abnormality on an imaging study which disrupts the normal opacification (filling) of a cavity or lumen. The opacification maybe physiological, for example, bile in the gallbladder or blood in a dural venous sinus, or maybe due to the installation of contrast medium, for example within a vessel, as part of a CT angiogram, within the bladder, during a cystogram, etc.


  • CT pulmonary angiogram: PE in the pulmonary artery interrupts normal contrast opacification of the vessel
  • CT colonogram: polyp in the colon prevents the normal gas and contrast filling of the bowel
  • MRCP: calculus in the common bile duct leaves a focus of low signal in the duct
Terms used in radiology