Multiple causes; can be isolated or syndromic

Autosomal recessive polycystic kidney disease is single gene disorder

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  Large, diffusely hyperechoic kidneys most common

  
  
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  May see discrete cysts or areas of tubular ectasia

  
  
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  Sometimes just echogenic medullary pyramids

Obstructive cystic dysplasia

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  Microscopic cysts develop due to chronic obstruction

  
  
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  Multiple interfaces → increased echogenicity

  
  
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  Macroscopic cortical cysts usually present

Trisomy 13

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  Echogenic kidneys seen in 50%

  
  
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  Look for holoprosencephaly, cyclopia, proboscis, midline facial cleft, polydactyly, congenital heart disease

  
  
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  Early-onset fetal growth restriction

Meckel-Gruber syndrome

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  Triad of findings: 2 needed to make diagnosis

  
  
  
  
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    Renal cystic dysplasia in > 90%

    
    
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    Encephalocele in 60-80%

    
    
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    Polydactyly in 55-75%

  
  

Echogenic kidneys are brighter than liver

Use high-resolution transducer to look for subtle cystic change/tubular ectasia

Use vaginal transducer for better resolution in 1st trimester or with breech presentation

If fluid is low, verify that membrane rupture has been ruled out: Relative contraindication to transvaginal ultrasound (TVUS) due to risk of introducing infection

Look for other anomalies, more likely syndromal diagnosis

Oligohydramnios may cause pulmonary hypoplasia

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  Measure chest:heart ratios to document small chest size

  
  
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  Normally, heart circumference is 1/2 of chest; heart area is 1/3 of chest