Birth defects are more common in the kidney and urinary system (urinary tract) than in any other system of the body. Defects can develop in the
Kidneys Kidney Defects There are several different birth defects that affect the kidneys (the two organs that filter waste from the blood to make urine). These defects are not usually apparent at the doctor's examination... read more —the two organs that filter waste from the blood to make urine
Ureters Ureter Defects Ureters are the tubes that transport urine from the kidneys (the two organs that filter waste from the blood to make urine) to the bladder (the expandable, muscular sac that holds urine). People... read more —the tubes that transport urine from the kidneys to the bladder
Urethra Urethra Defects The urethra is the tube that drains urine from the bladder out of the body. (See also Overview of Kidney and Urinary Tract Birth Defects.) There are several types of birth defects of the urethra... read more —the tube that drains urine from the bladder out of the body
Each kidney continuously produces urine, which then drains through the ureter into the bladder at a low pressure. From the bladder, urine drains through the urethra to exit the body. In males, the urethra is located in the penis. In females, the urethra ends in the vulvar area (the area of the external female genital organs). Usually, urine is free of bacteria and other infectious organisms.
A Look Inside the Urinary Tract
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Complications of urinary tract defects
Urinary tract defects may
Block or slow the flow of urine
Allow urine to flow backwards from the bladder to the kidneys (urinary reflux Urinary Reflux Urinary reflux is when urine flows backward from the bladder into the ureter and sometimes the kidney, usually because of a birth defect of the urinary tract. Each kidney continuously filters... read more )
Any birth defect that blocks or slows the flow of urine can cause urine to become stagnant, which can result in urinary tract infections Urinary Tract Infection (UTI) in Children A urinary tract infection is a bacterial infection of the urinary bladder ( cystitis), the kidneys ( pyelonephritis), or both. Urinary tract infections are caused by bacteria. Infants and younger... read more (UTIs) or formation of kidney stones Stones in the Urinary Tract Stones (calculi) are hard masses that form in the urinary tract and may cause pain, bleeding, or an infection or block of the flow of urine. Tiny stones may cause no symptoms, but larger stones... read more 
. If the flow of urine is blocked, it can cause pain or damage to the kidney.
Urinary reflux usually happens when defects involve the junction where a ureter connects to the bladder. Normally the junction allows urine to flow only one way, from the kidneys to the bladder. Defects of the junction can allow urine to flow backward from the bladder into the kidney (urinary reflux). In addition, other defects that block the flow of urine can increase the pressure in the bladder and cause urinary reflux. Reflux can affect one side or both sides.
Urinary reflux and/or frequent infections can damage the kidneys and ureters over time. Kidney damage can cause high blood pressure High Blood Pressure High blood pressure (hypertension) is persistently high pressure in the arteries. Often no cause for high blood pressure can be identified, but sometimes it occurs as a result of an underlying... read more 
and rarely kidney failure Overview of Kidney Failure Kidney failure is the inability of the kidneys to adequately filter metabolic waste products from the blood. Kidney failure has many possible causes. Some lead to a rapid decline in kidney function... read more .
Severe urinary tract defects in a fetus can cause little or no urine to be produced. The fetus's urine becomes part of the fluid that surrounds the fetus in the uterus (called amniotic fluid). If the fetus does not release enough urine, the amount of amniotic fluid is reduced. If there is too little amniotic fluid, the fetus's lungs, heart Overview of Heart Defects About one in 100 babies is born with a heart defect. Some are severe, but many are not. Defects may involve abnormal formation of the heart's walls or valves or of the blood vessels that enter... read more , face Introduction to Birth Defects of the Face, Bones, Joints, and Muscles Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. "Congenital" means "present at birth." Birth defects of the face and limbs are fairly... read more , and limbs Missing or Incompletely Formed Limbs Limbs can be missing, deformed, or incompletely developed at birth. Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. "Congenital"... read more 
may develop abnormally. Severe defects can cause death while the fetus is in the womb or shortly after birth.
Symptoms of Kidney and Urinary Tract Birth Defects
Many urinary tract defects cause no symptoms and are often discovered only when imaging studies are done for other reasons, or during a well-child examination Preventive Health Care Visits in Infants Healthy infants should be seen by their doctor often during the first year of life. Preventive health care visits (also called well-child visits) typically take place within a few days after... read more 
. Some kidney defects do not cause problems or become known until adulthood.
When urinary tract defects do cause symptoms, children may have
Abdominal pain, and/or vomiting due to blockage (obstruction) of urine flow
Children who have urinary obstruction are also at increased risk for significant urinary bleeding after a minor injury because the kidney is under pressure.
Diagnosis of Kidney and Urinary Tract Birth Defects
Before birth, prenatal ultrasonography and blood tests
After birth, imaging tests and sometimes cystoscopy
Before birth, urinary tract defects are often discovered by doctors during routine prenatal ultrasonography Ultrasonography Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more or other routine screening tests for hereditary disorders.
After birth, if doctors suspect a child has a urinary 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 , and 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). Sometimes, 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 or cystoscopy Cystoscopy A doctor can diagnose some disorders of the bladder and urethra (for example, bladder tumors, stones in the bladder, benign prostatic enlargement) by looking through a flexible viewing tube... read more . In cystoscopy, doctors look inside the bladder and urethra through a flexible viewing tube called a cystoscope (a type of endoscope).
To diagnose certain defects of the urinary tract, doctors sometimes do a test called voiding cystourethrography Cystography and cystourethrography 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 (VCUG). For voiding cystourethrography, a catheter is passed through the urethra into the bladder, a liquid that shows up on x-rays (contrast agent Radiopaque Contrast Agents During imaging tests, contrast agents may be used to distinguish one tissue or structure from its surroundings or to provide greater detail. Contrast agents include Radiopaque contrast agents... read more ) is put through the catheter, and x-rays are taken before, during, and after the child urinates.
As children grow, these tests may be repeated at scheduled intervals to assess how the bladder, ureters, urethra, and kidneys are developing or functioning and to assess if the child has outgrown the defect.
Treatment of Kidney and Urinary Tract Birth Defects
Sometimes surgery
Defects that cause symptoms or those that lead to increased pressure in the kidneys or bladder usually need to be surgically corrected.
