The kidneys are bean-shaped organs, each about the size of a fist. Each person has two kidneys and they are located near the middle of the back, just below the rib cage. The kidneys are responsible for filtering waste from our blood producing urine, which flows from the kidneys through tubes called ureters to the bladder. The bladder stores urine until releasing it during urination. Besides producing urine, the kidneys have many other functions such as regulating salt and mineral balance in our blood, controlling our blood pressure, maintaining healthy bones, and regulating our blood counts. Any damage to the kidneys can affect their ability to perform all of these important functions.
Renal hypoplasia, dysplasia, and aplasia refer to conditions in which the kidneys do not form correctly while a baby is in the womb. Combined, these conditions occur in 2-4% of the population. These conditions are the most common cause of kidney failure in children, although many children do not have any problems from these conditions and go undiagnosed. Renal aplasia occurs when the kidney does not form at all. There is no specific treatment for these conditions other than controlling salt and water balance and helping and monitoring your child’s growth, if needed.
Renal hypoplasia, dysplasia, and aplasia refer to conditions in which the kidneys do not form correctly while a baby is in the womb. Combined, these conditions occur in 2-4% of the population. These conditions are the most common cause of kidney failure in children, although many children do not have any problems from these conditions and go undiagnosed. Renal hypoplasia occurs when the kidney forms but it is too small. Renal dysplasia is a condition in which your kidney has abnormal tissue in it. One or both of your kidneys can be involved in all these conditions. There is no specific treatment for these conditions other than controlling salt and water balance and helping and monitoring your child’s growth, if needed.
Posterior urethral valves (PUV) are small congenital membranes of abnormal tissue that occur in the urethra of newborn boys. These occur in 1 to 8,000-25,000 births. These can cause severe blockage of the entire urinary tract, including the bladder, ureters, and kidneys. The kidneys produce amniotic fluid, the fluid surrounding a baby in the womb. PUV can cause a decreased amount of this fluid to be produced leading to poorly formed lungs and breathing problems, which are the most common cause of early death in PUV patients. Bladder problems associated with PUV can persist into adulthood, and approximately 15% of valve patients will progress to renal failure resulting in the need for dialysis and/or a kidney transplant. Treatment is directed at correcting chemical abnormalities due to poor kidney function and surgery is necessary early in life to remove the valves and restore normal urine flow.
Vesicoureteral reflux (VUR) is a condition in which urine flows abnormally from the bladder up towards the kidneys. VUR occurs in 1-2% of all children, but almost all children eventually out-grow their VUR. Under normal conditions, urine moves in a one-way fashion from the kidney to the ureter to the bladder and out of the body. When structural problems occur with any of these parts, urine can abnormally go back toward the kidneys instead of leaving the body through the urethra. Children who have VUR may be at risk for frequent urinary tract infections, which, over time, may cause scarring in the kidney and reduced function. Some types of VUR may be treated with antibiotics to prevent infections, while others may require surgery to prevent the backflow of urine to occur.
Ureteropelvic junction (UPJ) obstruction is a narrowing of the ureter between the renal pelvis (the area in the center of the kidney where urine collects) and the top portion of the ureter that results in obstructed urine flow. It is the most common cause of hydronephrosis (swelling of the kidney) in newborns. This kidney swelling is most commonly diagnosed on ultrasound prior to birth, but can be detected later in life. Boys are two times as likely to have obstruction of the UPJ as girls, and the left kidney is affected in approximately 2/3 of the cases. UPJ obstruction can only be repaired with surgery, and daily antibiotics are often prescribed to prevent urine infection. Since most cases of UPJ obstruction are corrected early in life, it rarely progress to kidney failure.
Ureterovesical junction (UVJ) obstruction results when the flow of urine is restricted around the area where the ureter inserts into the bladder. UVJ often results in dilation of the ureter (megaureter) and may result in bladder problems and hydronephrosis (swelling of the kidney) if urine flow is obstructed. UVJ obstruction is 2-4 times more common in boys and slightly more common on the left side. Antibiotics are frequently used to prevent urinary infection until the cause of the swollen urinary tract can be clarified with imaging studies such as ultrasound. While some cases can result in kidney damage and are corrected with surgery, most UVJ obstructions go away on their own.