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What is unilateral multicystic dysplastic kidney?

A unilateral multicystic dysplastic kidney is generally caused by abnormal development of the early metanephric tissue, where it does not develop into nephrons, but into dysplastic cystic tissue instead. When it is unilateral, it is usually isolated and not associated with genetic syndromes. However, approximately 5% of cases have other associated abnormalities. When bilateral, it is usually lethal and frequently has a genetic cause.

Typically, over the course of pregnancy and early childhood, the dysplactic kidney decreases in size and functionality, and the child is left with one functioning kidney, generally with compensatory hypertrophy.

For patients with one normal kidney, the prognosis is excellent, with a survival rate similar to the patient’s age and sex-matched controls from the United States life tables. However, proteinuria, hypertension, and renal insufficiency appear to be more common later in life. One study followed 157 patients with unilateral renal agenesis and a normal contralateral kidney diagnosed at a mean age of 37 years. The types and frequencies of abnormalities in this population included proteinuria, hypertension, and renal insufficiency.

On renal biopsy, these patients typically have focal segmental glomerulosclerosis, presumably reflecting chronic glomerular injury. The chronic glomerular injury is most likely a result from the compensatory glomerular hypertrophy and associated increase in glomerular perfusion pressure (intraglomerular hypertension).

Women with unilateral multicystic dysplastic kidney are recommended genetic counseling, a fetal echocardiogram test, and follow-up scans for fetal growth in the weeks following diagnosis.

Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!