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Kidney Defects

By

Ronald Rabinowitz

, MD, University of Rochester Medical Center;


Jimena Cubillos

, MD, University of Rochester School of Medicine and Dentistry

Last full review/revision Oct 2020| Content last modified Oct 2020
CLICK HERE FOR THE PROFESSONAL VERSION
Topic Resources

A Look Inside the Urinary Tract

A Look Inside the Urinary Tract

Complications of birth defects of the kidneys

  • Block or slow the flow of urine out of the kidneys

Types of Kidney Defects

A number of birth defects may result in abnormal kidneys. Kidneys may be

  • In the wrong location (ectopic kidneys)

  • Rotated the wrong way (malrotation)

  • Joined together (horseshoe kidney or fused kidneys)

  • Missing (agenesis)

  • Poorly functioning

  • Containing fluid-filled sacs (cysts), such as in polycystic kidney disease and multicystic dysplastic kidney

Kidneys in the wrong location and position

In the fetus, kidneys first develop in the pelvis and then move up and rotate into their normal location in the upper abdomen. If the kidneys are in the wrong place (ectopic kidneys) or are not rotated properly (malrotation), the normal drainage of urine from the kidneys through the ureters Ureters The ureters are muscular tubes—about 16 inches (40 centimeters) long—that attach at their upper end to the kidneys and at their lower end to the bladder. (See also Overview of the Urinary Tract... read more (the tubes that transport urine from the kidneys to the bladder) to the bladder Bladder The bladder is an expandable, muscular sac. Urine accumulates in the bladder as it arrives from the ureters. The bladder gradually increases in size to accommodate an increasing volume of urine... read more (the expandable, muscular sac that holds urine) may be blocked.

Children who have blockage that causes frequent urinary tract infections or other problems may need surgery. However, many children do not have symptoms and thus may not need surgery.

Horseshoe kidneys

A horseshoe kidney is the most common fused kidney defect. In horseshoe kidney, the fetus's kidneys join together into a horseshoe-looking shape. Because they are joined together, the kidneys do not usually move up and rotate into their normal location and also may not develop properly. Because of these factors, a horseshoe kidney may not drain properly, increasing the risk of urinary tract infections, kidney stones, and kidney damage. However, over half of children with a horseshoe kidney never have any symptoms. Children who have a horseshoe kidney may also have other birth defects.

Missing kidneys

In some children, one or both of the kidneys may not develop at all (kidney agenesis). Children who are missing both kidneys cannot survive.

In children who are missing only one kidney, the remaining kidney usually develops normally and often becomes bigger than normal to compensate for the missing one. In such cases, the child is expected to have a normal life expectancy and does not need any treatment.

Poorly functioning kidneys

Sometimes a kidney does not form properly and may not function properly or at all (kidney dysplasia). When only one kidney functions properly, it may become bigger than normal to make up for the loss of function of the other kidney. Because all of the functions normally done by two kidneys can be carried out adequately by one healthy kidney, children who have only one functioning kidney often lead normal, healthy lives. However, if dysplasia is widespread and affects both kidneys, children may need treatment to replace the kidney function. That is, they will need a kidney transplant Kidney Transplantation Kidney transplantation is the removal of a healthy kidney from a living or recently deceased person and then its transfer into a person with end-stage kidney failure. (See also Overview of Transplantation... read more Kidney Transplantation or dialysis Dialysis Dialysis is an artificial process for removing waste products and excess fluids from the body, a process that is needed when the kidneys are not functioning properly. There are a number of reasons... read more Dialysis (a way to remove waste products and excess fluids from the body).

Polycystic kidney disease

Polycystic kidney disease is a hereditary disorder in which many fluid-filled sacs (cysts) form in both kidneys. The kidneys grow larger but have less functioning tissue.

Autosomal recessive polycystic kidney disease is the rare form of this disorder that begins during childhood. In this disorder, the cysts become very large and cause serious illness. A severely affected newborn may die shortly after birth because kidney failure can develop before birth, leading to poor development of the lungs. The liver is also affected, and a child with this disorder tends to develop portal hypertension Portal Hypertension Portal hypertension is abnormally high blood pressure in the portal vein (the large vein that brings blood from the intestine to the liver) and its branches. Cirrhosis (scarring that distorts... read more , or high pressure in the blood vessels that connect the intestine and the liver (portal system). Eventually, liver failure Liver Failure Liver failure is severe deterioration in liver function. Liver failure is caused by a disorder or substance that damages the liver. Most people have jaundice (yellow skin and eyes), feel tired... read more and chronic kidney disease Chronic Kidney Disease Chronic kidney disease is a slowly progressive (months to years) decline in the kidneys’ ability to filter metabolic waste products from the blood. Major causes are diabetes and high blood pressure... read more occur. Infants who survive the newborn period may need kidney (and sometimes liver) transplantation.

Polycystic Kidney Disease

In polycystic kidney disease, many cysts form in both kidneys. The cysts gradually enlarge, destroying some or most of the normal tissue in the kidneys.

Polycystic Kidney Disease

Multicystic dysplastic kidney disease

Multicystic dysplastic kidney (MCDK) disease is the most common cyst-causing disease of the kidneys in children. In MCDK disease, the kidney does not develop normally and instead has multiple fluid-filled sacs (cysts) that grow inside the kidney and take over the normal kidney tissue. The kidney does not function at all. MCDK disease typically affects only one kidney. If it affects both kidneys, the fetus dies. However, children who have only one affected kidney often have a good outlook, depending on what other abnormalities, if any, they have. Sometimes the unaffected kidney has other defects that can cause blockage of urine flow.

MCDK is usually detected during routine prenatal ultrasonography, and most children have periodic ultrasounds after birth to determine whether the unaffected kidney is functioning properly. The affected kidney almost always shrinks and disappears. If the kidney does not go away, doctors sometimes remove it later in childhood. Because the unaffected kidney usually becomes bigger over time to compensate for the affected one, children usually have normal kidney function. If children have urinary blockage that causes frequent urinary tract infections or other problems in the functioning kidney, they may need surgery.

Diagnosis of Kidney Defects

  • Prenatal ultrasonography and tests before birth, and imaging tests and physical examinations after birth

  • Sometimes biopsy of the kidney

  • Sometimes genetic testing

After birth, kidney defects that cause no symptoms are often discovered when imaging studies are done for other reasons. If doctors suspect a child has a kidney defect, they typically do imaging tests such as ultrasonography Ultrasonography There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more , computed tomography Computed tomography There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more (CT), nuclear scans Nuclear Scans of the Digestive Tract Nuclear scans are tests that involve the use of harmless radioactive materials (see Radionuclide Scanning). The radioactive materials are ingested as part of a meal or in a drink or are given... read more , or magnetic resonance imaging Magnetic resonance imaging There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more (MRI). Rarely, doctors do intravenous urography Intravenous urography There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more .

People who have polycystic kidney disease may have genetic testing done to help them understand the probability that their children will inherit the disease.

Treatment of Kidney Defects

  • Sometimes surgical procedures

  • Sometimes a kidney transplant or dialysis

Treatment of kidney birth defects depends on the specific defect but, in general,

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