A parent brings a toddler, age 19 months, to the clinic for a regular check-up. When palpating the toddler’s fontanels, what should the nurse expect to find?
A. Open anterior and fontanel and closed posterior fontanel
B. Closed anterior and posterior fontanels
C. Closed anterior fontanel and open posterior fontanel
D. Open anterior and posterior fontanels
Correct Answer: B. Closed anterior and posterior fontanels
By age 18 months, the anterior and posterior fontanels should be closed. The diamond-shaped anterior fontanel normally closes between ages 9 and 18 months. The triangular posterior fontanel normally closes between ages 2 and 3 months. Fontanelles, often referred to as “soft spots,” are one of the most prominent anatomical features of the newborn’s skull. Fontanelle morphology may vary between infants, but characteristically they are flat and firm.
Option A: The most common conditions associated with a large anterior fontanelle or a delay in its closure are as listed: Down syndrome, achondroplasia, congenital hypothyroidism, rickets, and elevated intracranial pressures. Infants of African descent statically have larger fontanelles that range from 1.4 to 4.7 cm, and in terms of sex, the fontanelles of male infants will close sooner compared to female infants.
Option C: Often, the delayed closure of the posterior fontanelle is associated with hydrocephalus or congenital hypothyroidism. Unlike the anterior fontanelle, the posterior fontanelle is triangular and completely closes within about six to eight weeks after birth. On average, the posterior fontanelle is 0.5 cm in Caucasian infants and 0.7 cm in infants of African descent.
Option D: An elevated thyroid-stimulating hormone level on a newborn screening usually detects congenital hypothyroidism, but an abnormally large anterior fontanel in conjunction with an open posterior fontanel can be an early sign of the disorder. Myxedema and growth deficiency are later signs.