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Kidney Diseases

Fetal kidney problem

11/18/2005

Question:

On my sister`s 33wk ultrasound, it showed that the baby`s right kidney was dilated. What does this mean? Thanks

Answer:

A “dilated” (enlarged and stretched) kidney is one in which there is usually some sort of blockage to the flow of urine out of the kidney.  The urine therefore accumulates within the center of the kidney, causing it to slowly become stretched and enlarged rather like a balloon.  A blockage to urine flow can be caused, for instance, by a constriction within the kidney itself, by a narrowing anywhere along the ureter (the flexible muscular tube that connects each kidney to the bladder), or even by a blockage at the level of the urethra, which is the opening through which urine exits from the bladder. 

There are a number of developmental and congenital conditions that can cause such blockages, and most of them can be readily remedied by surgery.  At this time the best thing to do would be to have your sister's obstetrician refer her to a pediatric urologist, who can examine the actual ultrasound films and give her more specific information.  Depending on the severity of the dilation and the exact location of the blockage, further testing and even treatment may be possible even before the baby is born.  It is advisable to get the condition corrected as soon as feasible (which may be after the baby is born), since longstanding blockage of urine flow and dilation of the kidney can result in permanent kidney damage and decreased function.

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Response by:

Mildred   Lam, MD Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University