Neonatal Nurse Practitioner Practice Exam

Which neuromuscular finding is indicative of early gestational age?

1. 90 percent arm recoil

2. 100 percent arm recoil

3. 90 percent square window

4. Full flexion of limbs

The correct answer is: 90 percent square window

The correct choice is the 90 percent square window, which indicates a neuromuscular finding associated with early gestational age. In neonates, the square window test assesses the flexibility of the wrist when the hand is flexed towards the forearm. A 90-degree square window suggests that the infant is likely to be of lower gestational age, typically seen in premature infants. As gestational age increases, the infant's ability to flex their wrist decreases, leading to a more acute angle, which would indicate a more mature gestational age. In contrast, findings such as arm recoil are indicative of neuromuscular maturity: 100 percent arm recoil signifies that the infant can completely extend and then recoil back into a flexed position, which is more commonly observed in term infants. Full flexion of limbs further indicates maturity, as older neonates tend to maintain more flexed positions. These findings confirm that neuromuscular maturity increases with gestational age, making the 90 percent square window a distinct indicator of early gestational status.