Potter sequence is classically associated with which renal anomaly leading to pulmonary hypoplasia?

• A. Renal agenesis
• B. Polycystic kidney disease
• C. Hydronephrosis
• D. Renal hypoplasia

Answer: (A)

Potter sequence comes from severe oligohydramnios during fetal life, and the lack of amniotic fluid impairs lung development, leading to pulmonary hypoplasia. The classic cause of this oligohydramnios is bilateral renal agenesis, where the kidneys are absent and cannot produce fetal urine, a primary source of amniotic fluid. Other renal problems can reduce urine output and contribute to oligohydramnios, but bilateral renal agenesis is the textbook association with Potter sequence. So, absence of kidneys leads to very low amniotic fluid, which then results in underdeveloped lungs and the Potter phenotype.