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 which transforms urachus into solid cord / functionless remnant
  • Imaging: US to demonstrate findings:
    — 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
  • Clinical: may have umbilical discharge of pus or urine, inflammed anterior abdominal wall

Cases of Urachal Remnant

Cases of Urachal Cyst

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.

Cases of Patent Urachus

VCUG of patent urachus and urachal diverticulum
Lateral image from a voiding cystourethrogram performed by catheterizing the site of urine drainage at the patient’s umbilicus shows contrast filling the bladder and urethra as well as a large diverticulum at the dome of the bladder that nearly extends to the patient’s anterior abdominal wall.

Cases of Urachal Diverticulum

VCUG of patent urachus and urachal diverticulum
Lateral image from a voiding cystourethrogram performed by catheterizing the site of urine drainage at the patient’s umbilicus shows contrast filling the bladder and urethra as well as a large diverticulum at the dome of the bladder that nearly extends to the patient’s anterior abdominal wall.