What investigation should be ordered?

From the Guidelines

For patients presenting with suspected acute or recent transient ischemic attack or non-disabling ischemic stroke, I recommend ordering brain imaging, noninvasive vascular imaging, 12-lead ECG, and laboratory investigations as part of the initial assessment. This approach is supported by the Canadian Stroke Best Practice Recommendations, sixth edition practice guidelines, update 2017 1. The initial laboratory tests should include hematology, electrolytes, coagulation, renal function, random glucose or hemoglobin A1c, and troponin 1.

Initial Assessment

The following investigations should be considered:

• Brain imaging (CT or MRI)
• Noninvasive vascular imaging (including carotid imaging)
• 12-lead ECG
• Laboratory investigations, including:
  • Hematology (complete blood count)
  • Electrolytes
  • Coagulation (aPTT, INR)
  • Renal function (creatinine, e-glomerular filtration rate)
  • Random glucose or hemoglobin A1c
  • Troponin

Additional Tests

Subsequent laboratory tests may be considered during patient encounter or as an outpatient, including a lipid profile and screening for diabetes with either a fasting plasma glucose, or 2-hour plasma glucose, or glycated hemoglobin (A1C), or 75 g oral glucose tolerance test 1. CT angiography, including extracranial and intracranial vasculature from aortic arch to vertex, is recommended as an ideal way to assess both the extracranial and intracranial circulation 1.

Prioritization

The selection of investigations should follow a stepwise approach, beginning with non-invasive, cost-effective tests before proceeding to more complex or invasive procedures, always considering the pre-test probability of disease and the potential impact of test results on clinical management. Advanced imaging studies like CT scans, MRIs, or ultrasounds should be ordered based on specific clinical indications rather than routinely.

From the Research

Investigation Options

To determine the appropriate investigation to order, consider the following options:

• Complete Blood Count (CBC): a common laboratory test that evaluates the total numbers and characteristics of cell components in the blood 2, 3, 4
• Urinalysis: a test used to evaluate patients with suspected urinary tract infections (UTIs) 5
• Diffuse Reflectance Spectroscopy: a powerful tool for quantitative tissue characterization and disease diagnosis, although its application is more limited to specific clinical settings 6

Indications for Each Investigation

The choice of investigation depends on the clinical presentation and suspected diagnosis:

• CBC is useful for evaluating anemia, thrombocytopenia, leukopenia, polycythemia, thrombocytosis, and leukocytosis, as well as predicting the risk of cancer, cardiovascular disease, and metabolic syndrome 2, 3
• Urinalysis is essential for diagnosing and managing UTIs, including distinguishing between asymptomatic bacteriuria, uncomplicated UTI, and complicated UTI 5
• Diffuse Reflectance Spectroscopy is a specialized tool that may be used in specific clinical settings, such as tissue characterization and disease diagnosis, but its application is not as widespread as CBC or urinalysis 6

Considerations for Ordering Investigations

When ordering investigations, consider the following:

• The clinical context and suspected diagnosis
• The potential benefits and limitations of each investigation
• The availability and accessibility of each investigation in the clinical setting
• The need for specialized equipment or expertise, such as in the case of Diffuse Reflectance Spectroscopy 6