Kidney nontumor / medical renal

Developmental & cystic diseases

Congenital anomalies-general

Last author update: 2 April 2012
Last staff update: 14 December 2023

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PubMed Search: Kidney (congenital abnormalities [title])

Nikhil Sangle, M.D.
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Cite this page: Sangle N. Congenital anomalies-general. website. Accessed April 14th, 2024.
Definition / general
  • 10% of individuals have urinary tract malformations, although many are asymptomatic
  • 15% of congenital urogenital anomalies are secondary to an underlying chromosomal disorder
  • In children, 20% of chronic renal failure is due to renal dysplasia or hypoplasia
  • In adults, 10% of chronic renal failure is due to adult polycystic kidney disease
  • Mass ultrasound screening detects congenital renal and urinary tract anomalies in 1% but not recommended since most would ultimately be detected via symptoms; most commonly vesicoureteral reflux, ureteropelvic junction obstruction, ectopic kidney, renal dysplasia (Pediatr Nephrol 2012;27:949)
  • Complete absence of renal tissue; unilateral or bilateral; 0.03% of newborns but 0.3% of stillborn
  • Bilateral agenesis: incompatible with life; associated with large adrenal glands; leads to Potter (oligohydramnios) sequence; possible causes include maternal insulin dependent diabetes mellitus and male sex of fetus but usually no specific etiology (PLoS One 2010;5:e12375)
  • Unilateral agenesis: not fatal
Duplication of ureters
  • < 1% of individuals
  • Usually asymptomatic; may be associated with obstruction
Ectopic (displaced) kidneys
Horseshoe kidney
  • Most common congenital kidney anomaly, 0.15 - 0.25% of all newborns
  • 90% are fused at lower pole
  • Associated with obstruction, anomalous superior vena cava (Circ J 2012;76:1253)
  • Complete fusion of the kidneys produces a formless mass in the pelvis (pancake kidney)
  • Rare; failure of kidney to develop to normal size without scarring
  • Usually unilateral with a reduced number of nephrons and pyramids (6 or less) but otherwise normal architecture
  • Associated with PAX2 mutations (J Am Soc Nephrol 2001;12:1769)
  • Oligomeganephronia: type of hypoplasia with small kidney but hypertrophied nephrons due to compensatory hypertrophy caused by reduced number of nephrons
Renal tubular dysgenesis
  • Rare congenital abnormality of renal development characterized by short and poorly developed proximal convoluted tubules without dysplasia or cystic disease (Hum Pathol 1986;17:1259)
  • Characterized by oligohydramnios and the Potter sequence, pulmonary hypoplasia, calvarial bone hypoplasia with enlarged fontanels
  • Causes: acquired (associated with renal hypoperfusion, Pediatr Dev Pathol 1999;2:25) or autosomal recessive (mutations in genes associated with angiotensinogen, renin, angiotensin converting enzyme or angiotensin II receptor type 1, J Am Soc Nephrol 2006;17:2253, Hum Mutat 2012;33:316)
  • Identified in 1% of perinatal autopsies in 1991 (Hum Pathol 1991;22:147)
Diagrams / tables

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Renal hypoplasia

Case reports
Gross images

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Agenesis - bilateral

Incomplete duplication

Horseshoe kidney

Microscopic (histologic) images

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Oligomeganephronic renal hypoplasia

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