Failure of closure of lower abdominal wall resulting in exposed bladder

Inability to demonstrate fluid-filled bladder

Soft tissue mass/nodular contour of lower anterior abdominal wall due to exposed posterior bladder wall

Normal fluid

Absent bladder

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  Renal anomalies or other conditions with low/absent urine production are associated with oligo/anhydramnios

  
  
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  If associated with oligohydramnios in monochorionic twin, may indicate twin-twin transfusion syndrome

Cloacal exstrophy

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  Absent fluid-filled bladder, imperforate anus

  
  
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  Bowel herniation through abdominal wall defect → elephant trunk sign

Red flag for this diagnosis is normal amniotic fluid without visible bladder

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  Obtain midline sagittal image through torso for abdominal wall contour

  
  
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  Check cord insertion site; inferiorly displaced in bladder exstrophy

  
  
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  Evaluate for genital anomalies, which are common in both males and females

  
  
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  Look for anal dimple on axial image of perineum

Do not confuse cystic pelvic structures with bladder

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  Normal bladder fills and empties repeatedly during scan

  
  
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  Umbilical arteries encompass bladder as they course from internal iliac arteries to umbilicus

Use 3D surface-rendered ultrasound images to clarify anatomy