• Clinical science

Congenital anomalies of the kidneys


Congenital anomalies of the kidneys and urinary tract (CAKUT) are one of the most common malformations diagnosed in newborns. The pathogenesis of CAKUT is multifactorial; both specific genes and environmental factors (e.g., in utero exposure to ACE inhibitors) have been implicated in the development of CAKUT. Even though most cases are initially asymptomatic, up to 50% of children with end-stage renal disease have an underlying CAKUT. For this reason, early identification of these malformations is essential in order to prevent renal damage.


Anomalies of the collecting system

Malformation of the renal parenchyma

Renal dysgenesis

Congenital solitary kidney

Anomalies of kidney migration



Clinical features



  • Ultrasound imaging of the kidneys and bladder
    • First-line imaging modality
    • Detects anatomical abnormalities
    • Renal ultrasound is warranted for all children with recurrent UTIs or UTI in children < 24 months of age.
  • Voiding cystourethrogram
    • Detects retrograde movement of urine from the bladder to the urinary tract
    • Although the test is invasive and involves radiation exposure, it is warranted in patients with recurrent UTIs or single UTI and abnormal findings on renal ultrasound.
  • Intravenous pyelogram: detects anatomic abnormalities; has largely been replaced by ultrasound and CT urography
  • CT scan: detects anatomic abnormalities; can complement renal ultrasound if findings on ultrasound are equivocal


Differential diagnoses

Floating kidney


The differential diagnoses listed here are not exhaustive.