Failure of development of kidney can be unilateral or bilateral. Bilateral renal agenesis is a rare anomaly (incidence: 1 in 3000 birth). It is necessarily associated with oligohydramnios, which allows the uterine wall to compress the growing fetus, resulting in a spectrum of anomalies known as Potter's syndrome (also called Potter's sequence). These abnormalities include deformed limbs, a distinctive flat-nosed face, and pulmonary hypoplasia. Bilateral renal agenesis is compatible with prenatal but not with postnatal life; the infants with this anomaly die shortly after birth. Unilateral renal agenesis is a relatively common anomaly (incidence: 1 in 1000 births). Males are affected more often than females. Unilateral renal agenesis usually produces no problems because the sound kidney undergoes compensatory hypertrophy, ensuring that the overall renal function is normal.
Absence of the kidney generally results from failure of the ureteric bud to develop. Other possibilities include: failure of the ureteric bud to make contact with the metanephric blastema,
degeneration of the ureteric bud, or absence of the metanephric blastema.