"The intraureteric diverticulum", a manifestation of ureterocoele intussusception

An ectopic ureterocoele may present as a diverticular-like structure at the bladder base appearing during voiding cystography. The radiological appearances are described and the mechanism of formation as seen in serial 70 mm film is discussed. The conventional intravesical filling defect of an ureterocoele may not be recognised when the bladder is filled by contrast medium. This sign of extra-vesical intra-ureteric invagination is only seen during voiding.