Fetal multicystic dysplastic kidney (MCDK) is a condition that results from the malformation of the kidney during fetal development. The kidney consists of irregular cysts of varying sizes that resemble a bunch of grapes. It has no function, and nothing can be done to save this kidney. This defect generally only affects one of the kidneys, so typically the other healthy kidney will grow larger to compensate for the diseased one. Occasionally the disease affects both kidneys, which is incompatible with life, causing the fetus to be stillborn or to die shortly after birth.
In the United States, it is estimated that one in every 2,400 live births are affected by fetal MCDK. It generally occurs at the same rate in both females and males. In approximately 50% of babies diagnosed with this disease, other urological defects are found. However, the other defects can generally be corrected with surgery or by observation alone.
A fetal MCDK is generally diagnosed by ultrasound (sonogram) examination before birth. Evaluation of the kidneys is part of the routine ultrasound examination done by many obstetricians as part of their prenatal care around the 20th week of pregnancy.
Nothing can be done to treat a fetal MCDK. However, after the baby is born, the progress of the MCDK is tracked through a series of ultrasound examinations every six months to a year. It is monitored to make sure that it does not grow or develop a tumor. Most often, the MCDK will regress and disappear eventually, leaving the child with one healthy kidney. In addition to tracking the MCDK, the healthy kidney is screened for any defects such as a blockage or reflux. If there is something wrong, this allows the physicians time to intervene quickly to save the functioning kidney before it worsens.
The long-term outlook is generally very good for these children. It is rare for a child with MCDK to have symptoms later in life that stem from this problem.