You are called to a delivery of a woman with no prenatal care; she is in active labor but has no history of amniotic rupture. The biophysical profile done in the emergency center revealed severe oligohydramnios. When you get this infant to the nursery, you should carefully evaluate him for which of the following?

It is generally presumed that duodenal atresia and tracheoesophageal fistula lead to hydramnios (polyhydramnios) by interference with reabsorption of swallowed amniotic fluid. Hydramnios is also associated with approximately 80% of infants who have trisomy 18. Approximately 50% of women with anencephalic fetuses have polyhydramnios. Oligohydramnios occurs in association with congenital abnormalities of the fetal kidneys or other parts of the genitourinary tract, such as renal agenesis or obstruction, that impede normal formation or excretion of fetal urine.