Table of Contents
What Is Renal Agenesis?
Renal agenesis is a condition in which either one is absent (unilateral) or both (bilateral) kidneys since birth. It is a rare congenital (present at birth) defect. This condition happens around the fourth to sixth weeks of pregnancy due to the failure of the embryonic kidney cells to develop kidneys. This defect can be detected during prenatal ultrasound scans; thus, prompt treatment can be provided.
What Are the Types of Renal Agenesis?
There are two types of renal agenesis:
1. Bilateral Renal Agenesis - This occurs when both kidneys are missing. It is also known as Potter syndrome. It is commonly seen in boys. When both kidneys are absent, there is a lack of amniotic fluid. Amniotic fluid is the protective liquid present within the amniotic sac. It is a cushion for the growing embryo and exchanges nutrients between the mother and the baby. The decrease in amniotic fluid during the ultrasound is a reason for the early diagnosis of the condition. The rate of survival of infants without kidneys is very low. Without kidneys, the baby cannot produce urine, leading to low amniotic fluid and incomplete development of the lungs. The inheritance of bilateral renal agenesis can occur as an autosomal recessive trait. For the disease to manifest, a child needs to receive the altered gene from both parents. If both parents carry the mutated gene, all of their children have a:
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There is a 1 in 4 chance of not inheriting the mutated gene.
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There is a 1 in 4 chance of experiencing renal agenesis.
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There is a 1 in 2 chance of being a carrier without developing renal agenesis.
2. Unilateral Renal Agenesis - This means that only one kidney is absent. It is present in around one in one thousand births. This condition is not fatal and mostly asymptomatic. The baby has just one kidney, which grows larger and performs the functions of both kidneys to compensate for the absence of the other kidney. Most infants born with one kidney live a normal life but often have abnormal development of the genitals in both males and females.
What Causes Renal Agenesis?
The exact cause of renal agenesis is unknown. Human characteristics result from the interaction of two sets of genes received from the father and the mother. In such disorders, the diseased gene received either from the mother or father dominates the other normal gene, resulting in the presentation of the disease.
Unilateral agenesis is more common if there is poor growth of the fetus during pregnancy and in multiple births like twins, triplets, etc. The cause of bilateral renal agenesis is also unknown, though genetic predisposition has been found in rare cases. It is an autosomal genetic disorder. The risk of pregnancy affected by renal agenesis is around three to four percent.
What Are the Signs and Symptoms of Renal Agenesis?
Both bilateral and unilateral agenesis are associated with other defects related to the lungs, genitals and urinary tract, stomach and intestines, heart, muscles and bones, eyes, and ears.
Babies with unilateral renal agenesis may present with signs and symptoms at birth, in childhood, or later in life.
Symptoms include:
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Premature birth.
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Poor kidney function.
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Backward flow of urine.
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Kidney damage.
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Urine with protein or blood.
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Swelling in the face, hand, and legs.
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Babies with bilateral renal agenesis have a very low life expectancy. These defects are known as Potter syndrome. It occurs due to the non-production of urine. The symptoms include:
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Widely set eyes.
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Skin folds over the eyelids.
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Dry loose skin.
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Sharp nose.
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Low-set ears.
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Flat and broad nose.
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Small chin.
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Defective arms and legs.
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Underdeveloped lungs.
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Unusual genitals.
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Anal Atresia - Absence of normal anal opening.
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Esophageal Atresia - A congenital disability in which a part of the mouth's tube connecting the stomach (esophagus) is not developed properly.
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Clubbed feet.
How Is Renal Agenesis Diagnosed?
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Ultrasound - Renal agenesis is generally detected during the pregnancy ultrasound. The antenatal scan at the twentieth week gives a picture of the growing baby. Renal agenesis might be suspected during this scan if one or both kidneys are not seen. Genetic testing or genetic counseling might be recommended.
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Genetic counseling gives an insight into the conditions caused by gene changes and tells what to expect from them.
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Genetic testing is carried out on the placenta or amniotic fluid tissue to test for certain genes.
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MRI (Magnetic resonance imaging).
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Surgery.
How Is Renal Agenesis Treated?
Renal agenesis is treated based on the severity and type of agenesis. The standard treatment procedure involves keeping a tab on the baby with ultrasounds and making a planned delivery.
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Bilateral Renal Agenesis Treatment - The survival of babies born without kidneys is questionable. There is no treatment for bilateral renal agenesis. Supportive treatment is given to the newborns to make them comfortable with oxygen or certain medications. Once detected, the doctors inject a normal saline solution into the amniotic sac for the lungs to grow. Once the lungs begin to develop, the baby gets a little strength to survive outside the womb. A kidney transplant can be carried out in due course of time. The parents should decide whether to continue with the pregnancy or terminate it.
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Unilateral Renal Agenesis Treatment - Babies born with one kidney are usually asymptomatic. As long as the amniotic fluid is enough, they might not have any problems as the kidney grows and works for both. However, certain kids develop high blood pressure or backward urine flow, so they are treated for the same.
Can Renal Agenesis Be Prevented?
Prevention of renal agenesis is impossible because the exact cause of the conditions is unknown. Genetic predisposing factors cannot be altered. However, prenatal counseling for both parents is done so that they understand the risk of having a baby with renal agenesis. Pregnant women should limit the use of alcohol and certain medications that might hamper the development of the kidneys in the womb.
Conclusion:
The cause of renal agenesis is unknown. The defect is thought to pass from the parent's genes. In case of disorders at birth or congenital disorders, routine check-ups and screenings during pregnancy are very important to find any anomaly. Babies born with one kidney live a normal life with medical help. Whereas babies born without kidneys usually have a much higher risk of survival. If they survive, they need lifelong dialysis with a kidney transplant. Early detection can be helpful in certain cases and give the doctor time to make a proper treatment plan.
