Bilateral renal agenesis

Bilateral renal agenesis

Description

Bilateral renal agenesis is a lethal condition with an incidence of 0.1 to 0.3 per 1000 births. It can occur from the 5th week of embryonic development when the ureteric bud arises from the mesonephric duct. Interruption in the normal transition from pronephros to mesonephros (the earliest forms of fetal kidneys), necessary for later development of the metanephros, failure of development of the ureteral bud, or lack of normal nephron formation in the metanephric blastema may all lead to renal agenesis. As a consequence there may also be associated lack of ureteric development. Absence of normal urine production results in severe oligohydramnios which leads to a sequence of deformations including Potter’s syndrome, clubfeet, abnormal facies, small thorax with pulmonary hypoplasia, redundant skin, hip dislocation, and limb contractures.

Diagnosis

The diagnosis of bilateral renal agenesis should be considered when oligohydramnios is evident after 13 weeks, and is usually made by 16 to 20 weeks. Bilateral absence of kidneys is absolutely necessary to make the diagnosis. The bladder may be present but is usually not visualised due to lack of fluid. A thorough search for fetal kidneys should be made since kidneys may reside in an ectopic location. Fetal adrenals may be mistaken for kidneys since they may become enlarged or be hypoechoic. Ultrasound evaluation may be hampered by the lack of amniotic fluid. The administration of furosemide has been used to induce fetal urine production and may be helpful in the differential diagnosis of renal agenesis by producing a distended bladder. Normal bladder filling indicates the presence of functioning kidneys and rules out the diagnosis of renal agenesis. This methodology does not reliably differentiate renal agenesis from other forms of intrauterine renal failure.

Differential Diagnosis

Premature rupture of membranes may be confused with renal agenesis because of the presence of severe oligohydramnios. Other renal anomalies such as polycystic kidney disease and multicystic kidneys which may lead to oligohydramnios must be excluded. Intrauterine growth restriction may be associated with oligohydramnios without renal agenesis.

Sonographic Features

Bilateral absence of kidneys

Ureters and bladder not seen

Oligohydramnios

Joint dislocation, clubfeet, flexion contractures

Abnormally small thorax, lung hypoplasia

Flat facial profile, microcephaly

Growth restriction

Associated Syndromes

  • Acro-renal mandibular
  • Auriculo-renal dysplasia-hypospadias
  • Chromosomal
  • Congenital cystic adenomatous malformation
  • DK phocomelia
  • Fraser
  • Maternal diabetes
  • Melnick-Fraser (brachio-oto-renal)
  • MURCS association
  • Oto-renal-genital
  • Pallister-Hall
  • Polydactyly-cleft lip-hamartoma-renal-deafness-ret
  • VATER association

References

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