Pulmonary hypoplasia associated with renal agenesis or dysplastic kidneys is a feature of which sequence?

• A. Down syndrome
• B. Turner syndrome
• C. Potter sequence
• D. Noonan syndrome

Answer: (C)

Pulmonary hypoplasia with renal agenesis or severely dysplastic kidneys occurs in Potter sequence. This sequence results from oligohydramnios, because the fetal kidneys are not producing enough urine to maintain amniotic fluid levels. The lack of fluid compresses the fetus, leading to underdevelopment of the lungs and characteristic facial and limb findings. The pulmonary hypoplasia arises specifically because the lungs develop in a fluid-rich environment; when amniotic fluid is critically low, lung growth is stunted. Other listed conditions describe different congenital syndromes with features not driven by oligohydramnios from renal failure, so they don’t present this particular pattern.