BILATERAL RENAL AGENESIS – Case By Dr. Nitin Jadhav

Clinical history: Patient came for anomaly scan

Findings:

Complete anhydramnios is seen.

Bilateral kidneys are not seen in abdomen or in any ectopic location.

Discussion

Bilateral renal agenesis is a rare and serious congenital condition in which both kidneys fail to develop during fetal development. This condition results in the absence of both kidneys, which is a critical problem since the kidneys are essential for filtering waste and maintaining fluid and electrolyte balance.

Key Points About Bilateral Renal Agenesis:

1. Definition: Bilateral renal agenesis refers to the complete absence of both kidneys at birth. The kidneys are normally formed early in pregnancy, and their failure to develop leads to the absence of renal function.
2. Epidemiology:
   • Bilateral renal agenesis is extremely rare, occurring in approximately 1 in 4,000 to 1 in 10,000 live births.
   • It is usually fatal in utero or shortly after birth because the fetus is unable to produce urine (a condition called oligohydramnios), and urine production is essential for maintaining amniotic fluid levels.
3. Pathophysiology:
   • The kidneys develop from structures called the ureteric bud and metanephric mesoderm. Bilateral renal agenesis occurs when these structures fail to form or develop properly during fetal development.
   • Oligohydramnios (low amniotic fluid) is a consequence of the lack of kidney function, as the kidneys are responsible for producing the amniotic fluid. The absence of sufficient amniotic fluid restricts fetal movement and can lead to pulmonary hypoplasia (underdeveloped lungs), a major cause of death in infants with this condition.
4. Causes:
   • The exact cause of bilateral renal agenesis is often unknown, but it may be linked to:
     • Genetic factors: Mutations in genes responsible for kidney development, such as the WT1 gene, can lead to bilateral renal agenesis.
     • Syndromic associations: It may be associated with other genetic syndromes, including PAX2 gene mutations, and conditions like Fraser syndrome and VACTERL association (a group of birth defects).
     • Environmental factors: Maternal factors such as infections, drugs, or toxins during pregnancy could also play a role in the development of renal agenesis.
5. Diagnosis:
   • Antenatal ultrasound: Bilateral renal agenesis is most often diagnosed during a routine prenatal ultrasound, where the absence of kidneys and low amniotic fluid levels (oligohydramnios) are observed.
   • Postnatal diagnosis: In rare cases where the condition is not diagnosed antenatally, it may be identified after birth, typically with imaging studies like an ultrasound or CT scan.
   • Genetic testing: If a genetic syndrome is suspected, further testing may be done to look for specific mutations or chromosomal abnormalities.
6. Associated Findings:
   • Oligohydramnios: Low amniotic fluid due to the kidneys’ inability to produce urine, which is a hallmark of the condition.
   • Pulmonary hypoplasia: Inadequate lung development due to the lack of amniotic fluid, which is essential for fetal lung growth.
   • Facial deformities: Some infants with bilateral renal agenesis may also show features like flattened ears, wide-set eyes, or a flattened nose.
   • Other birth defects: In some cases, the condition may be part of a syndrome with other associated malformations, including anomalies of the limbs, heart, and other organs.
7. Prognosis:
   • In utero: Bilateral renal agenesis is typically fatal before birth due to the lack of amniotic fluid and subsequent pulmonary hypoplasia. Most pregnancies with bilateral renal agenesis result in spontaneous abortion or stillbirth.
   • Postnatal: If the condition is diagnosed after birth (in the rare case it is missed during prenatal scans), the prognosis is poor because the infant will have no kidney function. Without kidney function, the infant cannot survive for long, as kidney function is vital for removing waste from the body and maintaining electrolyte balance.
8. Genetic Counseling:
   • Since bilateral renal agenesis may have a genetic basis, families with a history of the condition are often referred for genetic counseling to discuss the risks for future pregnancies. If a genetic syndrome is suspected, testing may be offered.