A nurse is assessing a newborn diagnosed with myelomeningocele. Which assessment finding would be most concerning and require immediate intervention?

Increasing head circumference with bulging anterior fontanelle indicates hydrocephalus, a life-threatening complication requiring immediate intervention. Other findings like absence of reflexes or paralysis are expected in myelomeningocele and managed with standard care.

Clinical Reasoning and Priority Setting

This question requires you to recognize the most time-sensitive, life-threatening complication associated with myelomeningocele. While all the listed findings are abnormal and expected in this condition, the priority is determined by which finding signals an acute neurological emergency.

Analysis of the Correct Answer

Increasing head circumference with a bulging anterior fontanelle is the most concerning finding. This presentation is a classic sign of hydrocephalus, which is the most common and serious complication of myelomeningocele. The underlying pathophysiology is often an Arnold-Chiari II malformation, which obstructs the flow of cerebrospinal fluid (CSF). As CSF accumulates, it increases intracranial pressure (ICP). In a neonate, the skull sutures are not yet fused, so the head enlarges and the fontanelles bulge to accommodate the extra volume. This is a medical emergency because unchecked rising ICP can lead to brain herniation, irreversible brain damage, and death. The research evidence strongly supports this as a primary driver of early mortality. One long-term institutional study identified hydrocephalus as a significant factor associated with early death in this population ^[1]. A nationwide analysis and systematic review further confirms that the management of MMC-associated hydrocephalus is a central challenge, with a high proportion of neonates requiring CSF diversion procedures ^[2]. The need for and timing of such interventions is a key clinical focus, as highlighted in comparative studies of brain development in these patients ^[3].

Analysis of Incorrect Answers

1. Absence of deep tendon reflexes in the lower extremities is an expected finding. Myelomeningocele involves the protrusion of the meninges and spinal cord through a vertebral defect ^[2], causing damage to the nerves at and below the level of the lesion. This results in lower motor neuron signs such as areflexia. While important for neurological assessment and establishing a baseline, it is a static deficit related to the primary defect, not an acute, evolving crisis.

3. Flaccid paralysis of the legs with no spontaneous movement is also an expected finding directly related to the spinal cord lesion. The level of the defect determines the extent of motor and sensory loss. This finding is part of the newborn’s baseline condition and does not represent an immediate, life-threatening change that requires intervention over the other options.

4. Leakage of clear fluid from the neural tube defect site is a significant concern because it represents a direct portal for infection (meningitis) and CSF loss. However, the priority nursing action for this finding is to prevent infection by applying a sterile, moist, non-adherent dressing and positioning the infant to avoid pressure on the sac. While urgent, preventing infection is a secondary priority to the immediate threat of rising ICP from acute hydrocephalus, which can cause brain injury more rapidly. The clear fluid leak is a risk for a future complication, whereas the bulging fontanelle signals an ongoing, active neurological deterioration.