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Bilateral Renal Agenesis
Introduction
Bilateral renal agenesis is a uniformly lethal anomaly. Absence of the kidneys causes anhydramnios, resulting in pulmonary hypoplasia, characteristic facies, and positional extremity abnormalities ( Fig. 10.1 ). This constellation of findings was first described by Edith Potter, and bilateral renal agenesis has been termed Potter syndrome . The deformation sequence itself, which can occur following lack of amniotic fluid from any early insult (not merely from renal agenesis), is known as the oligohydramnios sequence or Potter sequence .
It is often challenging to diagnose absence of a structure, and bilateral renal agenesis can be particularly challenging because the lack of amniotic fluid impairs visualization. However, in population-based registries, renal agenesis has been diagnosed prenatally in about 90% of cases.
Disorder
Definition
Bilateral renal agenesis is the congenital absence of both kidneys and ureters.
Prevalence and Epidemiology
In Potter's original series, the prevalence of bilateral renal agenesis was approximately 1 : 3000 births. In population-based studies involving routine prenatal ultrasound (US), the prevalence is 1 : 8000 to 1 : 9000 pregnancie s . The actual birth prevalence is less common because approximately two-thirds of pregnancies with bilateral renal agenesis are terminated.
Bilateral renal agenesis is three times more common in males. It is also more common in the setting of pregestational diabetes. Based on data from the National Birth Defects Prevention Study, obesity and cigarette smoking approximately double the risk for bilateral renal agenesis, and binge drinking in the second month may more than triple the risk.
Associated anomalies have been reported in a high percentage of cases, including VACTERL ( v ertebral, a nal, c ardiac, t racheal, e sophageal, r enal, and l imb anomalies; see Chapter 146 ) association in 48% and gastrointestinal atresia in 28%. Partial laterality defects have been identified in more than 50% of cases, including intestinal malrotation, incomplete lobulation of the right lung, and persistence of the left superior vena cava. Aneuploidy has been reported in 7%. Bilateral renal agenesis is also a component of several syndromes, including branchiootorenal syndrome, Fraser syndrome (see Chapter 128 ), and sirenomelia (see Chapter 144 ).
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