From the Guidelines
Yes, a head CT is indicated in a female with loss of consciousness and vomiting.
Indications for Head CT
- Loss of consciousness and vomiting are symptoms that may indicate a serious underlying condition, such as intracranial bleeding, infection, or mass effect, which can be detected by a head CT 1.
- A noncontrast head CT is usually the initial test of choice for evaluating suspected progressive intracranial hemorrhage, mass effect, or hydrocephalus in the emergent setting 1.
- The yield of acute contributory findings on CT can range from 2% to 45% based on trial design and inclusion or exclusion criteria, and risk factors associated with intracranial findings include history of trauma or falls, hypertension, anticoagulant use, headache, nausea or vomiting, older age, impaired consciousness or unresponsiveness, neurologic deficit, and history of malignancy 1.
Considerations for Imaging
- MRI is complementary to CT, but may also be used as a first-line test based on clinical judgement 1.
- Contrast-enhanced CT examinations can be considered if intracranial infection, tumor, or inflammatory pathologies are suspected, but may not add significant value over noncontrast head CT examinations in the acute setting 1.
- A common practice is to perform a noncontrast screening head CT followed by a more sensitive MRI brain examination performed with and without contrast (or a contrast-enhanced head CT) in this setting 1.
From the Research
Indications for Head CT Scan
The decision to perform a head CT scan in a female patient with loss of consciousness and vomiting can be informed by several studies:
- A study published in 2017 2 found that vomiting was a significant predictor of abnormal head CT scans in patients with a history of head injury, with an odds ratio of 1.89.
- A 1999 study 3 suggested that head CT scans can be useful in patients with minimal head injury, including those with a history of loss of consciousness, as they may lead to changes in therapy.
- Research from 2011 4 identified vomiting, along with headache, loss of consciousness or amnesia, and alcohol intoxication, as risk indicators for abnormal brain CT scans after minor head injury.
- A 2018 study 5 applied the Canadian CT Head Rule to patients with minimal head injury and found that it was 100% sensitive for detecting intracranial hemorrhage, although the risk of such hemorrhage was very low.
- A 2012 study 6 examined the predictive value of vomiting for significant head injury and found a positive predictive value of 4% in adults, suggesting that while vomiting may be a reasonable indication for a CT head scan, it may not always require immediate performance.
Key Findings
- Vomiting is a significant predictor of abnormal head CT scans in patients with head injury 2, 4.
- Head CT scans can be useful in patients with minimal head injury, including those with a history of loss of consciousness 3.
- The Canadian CT Head Rule may be applied to patients with minimal head injury to guide the decision to perform a head CT scan 5.
- The positive predictive value of vomiting for significant head injury is relatively low, suggesting that immediate CT scans may not always be necessary 6.