A 1-hour-old boy is in the neonatal intensive care unit due to tachypnea and hypoxia. The infant was born at 39 weeks gestation via cesarean delivery due to recurrent variable decelerations. The pregnancy was complicated by lack of prenatal care. The infant weighs 3.2 kg (7 lb 1 oz). Physical examination shows a flattened nose and bilateral club feet. Breath sounds are markedly diminished bilaterally. The infant is intubated and mechanically ventilated, but oxygen levels do not improve. He dies an hour later. Which of the following is most likely to be found during autopsy of this infant?

Question

A 1-hour-old boy is in the neonatal intensive care unit due to tachypnea and hypoxia.  The infant was born at 39 weeks gestation via cesarean delivery due to recurrent variable decelerations.  The pregnancy was complicated by lack of prenatal care.  The infant weighs 3.2 kg (7 lb 1 oz).  Physical examination shows a flattened nose and bilateral club feet.  Breath sounds are markedly diminished bilaterally.  The infant is intubated and mechanically ventilated, but oxygen levels do not improve.  He dies an hour later.  Which of the following is most likely to be found during autopsy of this infant?

Quizplus · Accepted Answer

11ec160b_3752_3bb6_9249_d984182656d1_MD0001_00 This infant likely had Potter sequence, which is characterized by pulmonary hypoplasia, flat facies, and lower limb deformity (eg, club foot). Potter sequence is caused by a urinary tract anomaly that leads to decreased fetal urine output. It is classically associated with bilateral renal agenesis but can occur secondary to other etiologies, including posterior urethral valves or fetal exposure to ACE inhibitors. Because fetal urine is the main component of amniotic fluid, decreased fetal urine output can lead to low or absent amniotic fluid levels (ie, severe oligohydramnios). Inadequate amniotic fluid levels allow for increased external compression of the fetal face (flat facies) and extremities (eg, club foot). In addition, the umbilical cord is often compressed such that fetal heart rate abnormalities (eg, recurrent decelerations) are common during labor. Amniotic fluid also provides the fluid and growth factors needed for fetal lung development. Therefore, neonates with Potter sequence have pulmonary hypoplasia due to the lack of normal alveolar distension by aspirated amniotic fluid. Both lungs are affected, and respiratory failure (ie, hypoxia) is the most common cause of death in affected infants. (Choice A) Congenital diaphragmatic hernia can cause neonatal hypoxia due to lung compression by the herniated abdominal contents; however, infants typically have unilateral (not bilateral) absent breath sounds. In addition, there is no association with flat facies or limb deformity. (Choices B and E) Infants with gastrointestinal obstruction proximal to the small bowel (eg, duodenal atresia, tracheoesophageal fistula) may have respiratory distress due to stomach distension and subsequent lung compression. However, these neonates have impaired amniotic fluid swallowing in utero, leading to polyhydramnios. (Choice D) Surfactant decreases alveolar surface tension, and surfactant deficiency (most commonly associated with prematurity) can cause alveolar collapse and neonatal respiratory distress syndrome. However, surfactant deficiency is not typically associated with flat facies or limb deformity. Educational objective: Potter sequence results from a urinary tract anomaly (eg, bilateral renal agenesis) that causes decreased fetal urine output and severe oligohydramnios. The lack of amniotic fluid causes increased fetal compression (eg, flat facies, limb deformity) and pulmonary hypoplasia (eg, neonatal hypoxia), which is the most common cause of death in affected neonates. __________ References: Rare manifestations of Potter sequence: a case report. (http://www.ncbi.nlm.nih.gov/pubmed/32347825)

A 1-Hour-Old Boy Is in the Neonatal Intensive Care Unit