Differential diagnosis of pediatric pelvic mass

Approach to the differential diagnosis of pelvic mass:

  • Ultrasound should be used to determine the organ of origin
  • Always check the renal fossa to exclude ectopic kidney
  • If the bladder is distended, consider causes of bladder outlet obstruction
  • A cystic pelvic mass in the midline in association with the umbilicus is often an urachal remant
  • A cystic pelvic mass in a female that is not in the midline is ovarian in origin until proven otherwise
  • A cystic pelvic mass in a female in the midline posterior to the bladder is hydrometrocolpos
  • Presacral masses will need further imaging with CT or MRI