May also be called: Kidney Dysplasia; Multicystic Dysplastic Kidney; MCDK

Renal dysplasia (REE-nul dis-PLAY-zhee-uh) is a condition in which one or both of a baby's kidneys develop abnormally in the womb, often causing cysts (fluid-filled sacs) to replace normal kidney tissue.

More to Know

Kidneys filter waste products from the blood to form urine (pee), which flows from the kidneys to the bladder through thin tubes called ureters. Normally, when a fetus is developing, ureters grow into kidneys and branch out to form the network that collects urine.

With renal dysplasia, this process is disrupted, and urine can't flow out of the affected kidney as it's supposed to. Instead, the urine collects inside the kidney and forms cysts. Renal dysplasia can be related to a genetic disorder, or prescription or illegal drugs used by a mother during pregnancy.

Usually, renal dysplasia is found in only one kidney, but in some cases, both kidneys may be affected. When only one kidney is involved, babies usually grow normally and may have no symptoms or health problems. Symptoms that can occur include problems with kidney function, urinary tract infections (UTIs), and, rarely, high blood pressure.

When renal dysplasia affects both kidneys, babies generally don't survive pregnancy; those who do need dialysis treatment and a kidney transplant early in life.

Keep in Mind

Most kids with renal dysplasia in only one kidney require no treatment and don't experience any problems or complications as a result of the condition. The unaffected kidney can take over and effectively do the work of both kidneys. However, these children still need to be closely monitored for UTIs and high blood pressure, both of which can damage the healthy kidney.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.