We just had our first ultrasound at 20 weeks and our baby has extra fluid in his kidney. What does this mean for him?
The kidneys are maturing, just like your unborn baby's lungs, meaning at times they might have fluid. There's probably every expectation that this will "go away" as your unborn baby continues to develop.
In some cases extra fluid in a kidney can indicate a condition called hydronephrosis. According to the National Kidney Foundation, this condition "is the most common abnormality detected on the ultrasound." With this condition, the kidneys may not function properly.