Multicystic dysplastic kidney
Multicystic dysplastic kidney is also called renal dysplasia or kidney dysplasia, is one of the most frequently identified congenital anomalies of the urinary tract in which the internal structures of one or both of a fetus’ kidneys do not develop normally while in the womb. During normal development, two thin tubes of muscle called ureters grow into the kidneys and branch out to form a network of tiny structures called tubules. The tubules collect urine as the fetus grows in the womb. In multicystic dysplastic kidney or kidney dysplasia, the tubules fail to branch out completely. Urine that would normally flow through the tubules has nowhere to go. Urine collects inside the affected kidney and forms fluid-filled sacs called cysts. The cysts replace normal kidney tissue and prevent the kidney from functioning. A multicystic dysplastic kidney has no function and nothing can be done to save it.
Multicystic dysplastic kidney is a common condition. Scientists estimate that multicystic dysplastic kidney affects about one in 4,000 babies 1. This estimate may be low because some people with multicystic dysplastic kidney are never diagnosed with the condition. About half of the babies diagnosed with this condition have other urinary tract defects 2.
Multicystic dysplastic kidney can be unilateral (affect one kidney) or, in rare cases, bilateral (affects both kidneys). One or both kidneys grow cysts (fluid-filled sacs) that look like a bunch of grapes. The cysts cause the unhealthy kidney to not work. Over time, most of the cysts shrink and go away. Other times, children need surgery to remove the unhealthy kidney. With unilateral multicystic dysplastic kidney, the healthy kidney grows larger to do the work of the unhealthy kidney.
Babies with severe multicystic dysplastic kidney affecting both kidneys generally do not survive birth. Those who do survive may need the following early in life:
- blood-filtering treatments called dialysis
- a kidney transplant
Children with multicystic dysplastic kidney in only one kidney have normal kidney function if the other kidney is unaffected. Those with mild dysplasia of both kidneys may not need dialysis or a kidney transplant for several years.
Figure 1. Multicystic dysplastic kidney ultrasound
Multicystic dysplastic kidney causes
Doctors do not know what causes fetal multicystic dysplastic kidney. Sometimes, multicystic dysplastic kidney can be genetic (passed down through families) if other family members also have multicystic dysplastic kidney. Genes pass information from both parents to the child and determine the child’s traits. Sometimes, parents may pass a gene that has changed, or mutated, causing multicystic dysplastic kidney.
Genetic syndromes that affect multiple body systems can also cause multicystic dysplastic kidney. A syndrome is a group of symptoms or conditions that may seem unrelated yet are thought to have the same genetic cause. A baby with multicystic dysplastic kidney due to a genetic syndrome might also have problems of the digestive tract, nervous system, heart and blood vessels, muscles and skeleton, or other parts of the urinary tract.
A baby may also develop multicystic dysplastic kidney if his or her mother takes certain prescription medications during pregnancy, such as some used to treat seizures and high blood pressure. A mother’s use of illegal drugs, such as cocaine, during pregnancy may also cause multicystic dysplastic kidney in her unborn child.
Who is more likely to develop multicystic dysplastic kidney?
Babies who are more likely to develop multicystic dysplastic kidney include those:
- whose parents have the genetic traits for the condition
- with certain genetic syndromes affecting multiple body systems
- whose mothers used certain prescription medications or illegal drugs during pregnancy
Multicystic dysplastic kidney symptoms
Many babies with multicystic dysplastic kidney in only one kidney have no signs of the condition. In some cases, the affected kidney may be enlarged at birth and may cause pain. Most cases of multicystic dysplastic kidney are detected during fetal ultrasonography and are reported as early as 15 weeks’ gestation.
Multicystic dysplastic kidney complications
The complications of multicystic dysplastic kidney can include
- Hydronephrosis of the working kidney. A baby with kidney dysplasia in only one kidney might have other urinary tract defects. When other defects in the urinary tract block the flow of urine, the urine backs up and causes the kidneys and ureters to swell, a condition called hydronephrosis. If left untreated, hydronephrosis can damage the working kidney and reduce its ability to filter blood. Kidney damage may lead to chronic kidney disease and kidney failure.
- Urinary tract infection (UTI). A urine blockage may increase a baby’s chance of developing a urinary tract infection (UTI). Recurring UTIs can also lead to kidney damage.
- High blood pressure.
- A slightly increased chance of developing kidney cancer.
Multicystic dysplastic kidney diagnosis
Health care providers may be able to diagnose kidney dysplasia during a woman’s pregnancy using a fetal ultrasound, also called a fetal sonogram. Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure. Fetal ultrasound is a test done during pregnancy to create images of the fetus in the womb.
Due to the increased use of prenatal imaging, many children with multicystic dysplastic kidney are diagnosed before birth. Health care providers do not always diagnose kidney dysplasia before a baby is born. After birth, health care providers often diagnose multicystic dysplastic kidney during an evaluation of the child for a urinary tract infection (UTI) or another medical condition. A health care provider uses ultrasound to diagnose kidney dysplasia after the baby is born to confirm the diagnosis. On ultrasound the kidney will appear as several cysts with no surrounding functioning kidney. In some situations a renal scan may be ordered to confirm that the kidney has no function.
Multicystic dysplastic kidney treatment
There is no treatment for multicystic dysplastic kidney. If multicystic dysplastic kidney is limited to one kidney and the baby has no signs of kidney dysplasia, no treatment may be necessary. However, the baby should have regular checkups and be monitored by the pediatric urologist (doctor who cares for problems with the urinary tract) that include:
- checking blood pressure.
- testing blood to measure kidney function.
- testing urine for albumin, a protein most often found in blood. Albumin in the urine may be a sign of kidney damage.
- performing periodic ultrasounds to monitor the damaged kidney and to make sure the functioning kidney continues to grow and remains healthy.
Most often, the multicystic dysplastic kidney will regress and disappear eventually, leaving the child with one healthy kidney.
If the multicystic dysplastic kidney is not disappearing or is growing larger, surgery may be necessary. The surgery to remove the kidney is called a nephrectomy, this surgery can be done through a minimally invasive approach either robotically or laparoscopy. The advantages are smaller incisions and a faster recovery.
Multicystic dysplastic kidney prognosis
The long-term outlook for a child with multicystic dysplastic kidney in only one kidney is generally good. A person with one working kidney, a condition called solitary kidney, can grow normally and may have few, if any, health problems.
The affected kidney may shrink as the child grows. By age 10, the affected kidney may no longer be visible on x-ray or ultrasound 3. Children and adults with only one working kidney should have regular checkups to test for high blood pressure and kidney damage. A child with urinary tract problems that lead to failure of the working kidney may eventually need dialysis or a kidney transplant.
For a child with multicystic dysplastic kidney in both kidneys
The long-term outlook for a child with multicystic dysplastic kidney in both kidneys is different from the long-term outlook for a child with one dysplastic kidney. A child with multicystic dysplastic kidney in both kidneys:
- is more likely to develop chronic kidney disease.
- needs close follow-up with a pediatric nephrologist—a doctor who specializes in caring for children with kidney disease. Children who live in areas that don’t have a pediatric nephrologist available can see a nephrologist who cares for both children and adults.
- may eventually need dialysis or a kidney transplant.
- Gordon AC, Thomas DF, Arthur RJ, et al. Multicystic dysplastic kidney: is nephrectomy still appropriate? The Journal of Urology. 1988;140(5 Pt 2):1231-1234.
- Fetal multicystic dysplastic kidney. Anne & Robert H. Lurie Children’s Hospital of Chicago website. www.luriechildrens.org . Updated January 2014. Accessed July 14, 2014.
- Hayes WN, Watson AR, Trent & Anglia MCDK Study Group. Unilateral multicystic dysplastic kidney: does initial size matter? Pediatric Nephrology. 2012;27(8):1335–1340.
