DDX of anomalies of renal formation

Approach to the DDX of anomalies of renal formation:

  • While performing renal ultrasound for the followup of findings on prenatal ultrasound or as part of the workup for urinary tract infection one should search for anomalies of renal formation:
    Agenesis of the kidney evidenced by an empty renal fossa – but before this diagnosis can be made, abnormalities of renal ascent (ectopic kidney, horseshoe kidney, intrathoracic kidney) must be ruled out
    Fetal lobulations of the kidney which disappear in a few weeks
    Dromedary hump which is an abnormality in renal contour of the lateral left kidney which can mimic a renal mass
    Tamm Horsfall proteins which manifest as echogenic renal pyramids which resolve by the end of the neonatal period
    Duplication of the kidney along with ectopic ureterocele which can lead to vesicoureteral reflux