Urachal Remnant

  • Etiology: urachus is canal connecting bladder of fetus with allantois which is a structure that contributes to formation of umbilical cord, lumen of urachus normally obliterated during embryonic development, transforming urachus into solid cord / functionless remnant
    — Patent urachus – bladder communicates with umbilicus
    — Urachal sinus – starts at umbilicus and terminates blindly along tract
    — Urachal cyst – urachus closed at each end with cyst in middle
    — Urachal diverticulum – starts at bladder and terminates blindly along tract
  • Imaging: US to demonstrate findings
  • Clinical: may have umbilical discharge of pus or urine, inflammed anterior abdominal wall along omphalovesical duct / ligament

Cases of Urachal Remnant

CT of infected urachal cyst
Axial (left) and sagittal (right) images from a CT with contrast of the abdomen shows a midline cystic lesion with a thick enhancing wall and surrounding inflammatory change just inferior to the umbilicus that appears to course to the dome of the bladder on the sagittal image.