Sunken fontanelle is a sign of?

WCL Staff Nurse - 2019

Child Health Nursing (Pediatrics)

Easy

Appeared in: WCL Staff Nurse - 2019

Explanation

A sunken fontanelle is a primary indicator of dehydration in infants.
Dehydration reduces the overall fluid volume in the body, including the cerebrospinal fluid (CSF) that cushions the brain.
This decrease in fluid volume and intracranial pressure causes the soft, membranous fontanelle to retract and appear sunken.
Other signs of dehydration often accompany a sunken fontanelle, such as dry mouth, decreased urine output, and lethargy.

Option B: Hydrocephalus is characterized by an excessive accumulation of cerebrospinal fluid (CSF) within the brain's ventricles, which leads to increased intracranial pressure (ICP).
Option C: Down's syndrome is a genetic condition (Trisomy 21) associated with characteristic physical features, intellectual disability, and hypotonia. While fontanelles may be larger or have delayed closure, a sunken fontanelle is not a defining feature.
Option D: Turner's Syndrome is a genetic condition (monosomy X) affecting females, characterized by features like a webbed neck, low posterior hairline, and lymphedema of the hands and feet at birth.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Clinical significance of fontanelle assessment in infants as background academic context rather than a clinical decision trigger.
Fontanelle assessment is a rapid, non-invasive tool for nurses to gauge an infant's hydration and neurological status at the bedside.
A sunken fontanelle is a red flag for dehydration, which can progress rapidly in infants, leading to electrolyte imbalances, shock, and organ damage if not treated promptly.
Nurses must educate parents on recognizing signs of dehydration, including changes in the fontanelle, and when to seek immediate medical care.

How to Approach the Question

First, identify the key clinical sign in the question: 'sunken fontanelle'.
Analyze the image provided, which visually confirms a depression on the infant's head, consistent with a sunken fontanelle.
Recall the pathophysiology related to fontanelle changes. A sunken appearance is related to a decrease in volume/pressure, while a bulging appearance is related to an increase.
Evaluate each option based on this understanding. Dehydration involves fluid loss, which would decrease intracranial volume and cause a sunken fontanelle.
Consider the other options. Hydrocephalus involves excess fluid, causing bulging. Down's and Turner's syndromes are genetic disorders not primarily defined by a sunken fontanelle.
Conclude that dehydration is the only option that directly explains the pathophysiology of a sunken fontanelle.

Concept Tested & Keywords

Concept Tested: Clinical significance of fontanelle assessment in infants.
Stem keywords: Sunken fontanelle, sign
Lead-in keywords: is a sign of
Clinical cues: The visual cue of a depressed soft spot on the infant's head is the key finding.

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E6 Nelson Textbook of Pediatrics(2024) — Volume 2 pp. 1357-1359, 1386-1388