Maternity Nursing Q 136
Which of the following is true regarding the fontanels of the newborn?
A. The anterior is triangular shaped; the posterior is diamond-shaped.
B. The posterior closes at 18 months; the anterior closes at 8 to 12 weeks.
C. The anterior is large in size when compared to the posterior fontanel.
D. The anterior is bulging; the posterior appears sunken.
Correct Answer: C. The anterior is large in size when compared to the posterior fontanel.
The anterior fontanel is larger in size than the posterior fontanel. Additionally, the anterior fontanel, which is diamond-shaped, closes at 18 months, whereas the posterior fontanel, which is triangular shaped, closes at 8 to 12 weeks. Neither fontanel should appear bulging, which may indicate increased intracranial pressure, or sunken, which may indicate dehydration.
Option A: The anterior fontanelle is the largest of the six fontanelles, and it resembles a diamond-shape ranging in size from 0.6 cm to 3.6 cm with a mean of 2.1 cm. Unlike the anterior fontanelle, the posterior fontanelle is triangular and completely closes within about six to eight weeks after birth.
Option B: The average closure time of the anterior fontanelle ranges from 13 to 24 months. The posterior fontanel completely closes within about six to eight weeks after birth.
Option D: In addition to being the largest, the anterior fontanelle is also the most important clinically. This structure offers insight into the newborn’s state of health, especially hydration and intracranial pressure status. A sunken fontanelle is primarily due to dehydration. Other clinical indicators that support the diagnosis of dehydration are dry mucous membranes, sunken eyes, poor tear production, decreased peripheral perfusion, and lack of wet diapers. Furthermore, a bulging fontanelle may indicate a rise in intracranial pressure, suggesting multiple pathologies: hydrocephalus, hypoxemia, meningitis, trauma, or hemorrhage.