In a pediatric patient with head trauma, how do the frequency, timing, and duration of vomiting influence the decision to obtain a non‑contrast head CT?

Vomiting After Pediatric Head Trauma: Frequency, Timing, and CT Decision-Making

Direct Answer

In pediatric head trauma, vomiting alone—regardless of frequency or timing—places the child in an intermediate-risk category and warrants consideration for CT imaging, though observation is an acceptable alternative in the absence of other high-risk features. 1

Risk Stratification Framework

High-Risk Features Requiring Immediate CT (Independent of Vomiting)

These features mandate immediate non-contrast head CT regardless of vomiting status:

• Glasgow Coma Scale ≤14 or altered mental status – associated with ~4.3% risk of clinically important traumatic brain injury 1
• Signs of basilar skull fracture – carries ~4.3% risk of clinically important injury 1
• Palpable skull fracture in children <2 years 1
• Post-traumatic seizure 2
• Focal neurologic deficit 2

Vomiting as an Intermediate-Risk Factor

Vomiting is explicitly listed as an intermediate-risk criterion in validated clinical decision rules, with an estimated clinically important traumatic brain injury risk of approximately 0.8%. 1 The key nuances:

• Frequency thresholds vary by guideline: The ACEP guidelines recommend CT for vomiting in adults with loss of consciousness or post-traumatic amnesia 2, while the CATCH rule includes "persistent vomiting" as a high-risk factor in children 3
• Single episode vs. multiple episodes: British guidelines historically required >1 episode in adults and ≥3 episodes in children, though recent evidence questions whether this threshold meaningfully stratifies risk 4
• Timing post-injury: No specific time window has been validated; vomiting occurring at any point after trauma contributes to intermediate risk 1

Very Low-Risk Criteria (CT Can Be Safely Avoided)

Children meeting all of the following PECARN criteria have <0.05% risk of clinically important traumatic brain injury and do not require CT 1:

• Glasgow Coma Scale 15
• Normal mental status
• No loss of consciousness
• No vomiting
• No severe mechanism of injury
• No severe headache
• No signs of basilar skull fracture

Evidence-Based Approach to Vomiting

The Observation Strategy

Clinical observation before CT decision-making is an effective strategy that reduces unnecessary radiation exposure without delaying diagnosis of significant traumatic brain injury. 2, 1 Specifically:

• Every additional hour of emergency department observation is associated with decreased CT utilization across all risk groups 2
• All children with significant injuries in validation studies underwent immediate CT; none were missed by observation protocols 2
• Observation is most appropriate for intermediate-risk patients where vomiting is the primary concern 1

Positive Predictive Value of Vomiting Alone

When vomiting is the sole indication for CT, the positive predictive value for significant head injury is only 4% in adults and 3.7% in children, and none of these injuries required neurosurgical intervention in one retrospective series. 4 This suggests:

• Vomiting has low specificity for serious injury
• When present with other risk factors, vomiting increases concern
• Isolated vomiting without other features may justify observation over immediate CT

Duration and Persistence

"Persistent vomiting" appears in the CATCH rule as a high-risk factor, though the exact definition (number of episodes, time span) is not standardized. 3 Practical interpretation:

• Worsening or ongoing vomiting during observation period should lower threshold for CT 3
• Single episode of vomiting in an otherwise well-appearing child may be managed with observation 1
• Vomiting that resolves and does not recur during a 4-6 hour observation period suggests lower risk 2

Algorithmic Approach

Step 1: Assess for High-Risk Features

If any high-risk feature present (GCS ≤14, altered mental status, basilar skull fracture signs, palpable skull fracture in infant, seizure, focal deficit) → immediate CT 1

Step 2: If No High-Risk Features, Assess Vomiting in Context

• Vomiting + loss of consciousness or amnesia → CT recommended per ACEP Level A 2
• Vomiting + severe headache → CT should be considered per ACEP Level B 2
• Vomiting + dangerous mechanism (fall >3 feet/5 stairs, high-impact collision) → CT should be considered 2
• Isolated vomiting (1-2 episodes) in well-appearing child → observation acceptable alternative to CT 1

Step 3: Observation Protocol

• Monitor for 4-6 hours minimum 2
• Reassess neurologic status hourly 2
• If vomiting persists, worsens, or new symptoms develop → proceed to CT 3
• If child improves and vomiting resolves → safe discharge with return precautions 1

Critical Pitfalls to Avoid

Do not rely on vomiting frequency cutoffs (e.g., "3 episodes") as absolute thresholds—the evidence shows that even single episodes warrant consideration for imaging when combined with other intermediate-risk factors. 4, 3

Do not discharge a child with ongoing vomiting without either obtaining CT or completing an adequate observation period—persistent vomiting is a validated high-risk feature in the CATCH rule. 3

Do not obtain skull radiographs instead of CT—they miss up to 50% of intracranial injuries and provide no information about brain parenchyma. 1

Do not apply adult clinical decision rules to pediatric patients—use PECARN criteria for children, which have been validated in over 42,000 pediatric patients. 2, 1

Special Populations

In children <2 years, vomiting combined with non-frontal scalp hematoma, loss of consciousness >5 seconds, or severe mechanism places them in intermediate risk (0.9% clinically important traumatic brain injury risk) and warrants CT consideration. 1

In suspected non-accidental trauma, vomiting does not guide imaging decisions—CT or MRI is recommended regardless of clinical features. 1