Table 1.

Examples of coding from physician documentation of diagnostic impressions

	Documentation	ICD-10-CA codes*	Interpretation of codes
Physician 1: clear diagnosis	82F known AF, likely cardioembolic left hemispheric TIA. Differential includes seizures. CT/CTA: no stroke, left MCA-M2 occlusion	G45.8 (MP) Q R56.88 (OP) I66.0 (OP) I48.90 (OP)	Other transient cerebral ischaemic attacks and related syndromes Seizure—queried Occlusion and stenosis of MCA AF, unspecified
Physician 2: uncertainty	82F history of AF, transient aphasia and right arm weakness. Cerebral ischaemia vs seizure. CT/CTA: no stroke, left MCA-M2 occlusion	R47.0 (MP) R29.8 (OP) Q I63.5 (OP) Q R56.88 (OP) I66.0 (OP) I48.90 (OP)	Aphasia Right arm weakness Cerebral infarction—queried Seizure—queried Occlusion and stenosis of MCA AF, unspecified
Physician 3: lack of definite diagnosis	82F with AF, transient aphasia and right arm weakness. CT/CTA: no stroke, left MCA-M2 occlusion	R47.0 (MP) R29.8 (OP) I66.0 (OP) I48.90 (OP)	Aphasia Right arm weakness Occlusion and stenosis of MCA AF, unspecified

*These represent real codes generated by a coding specialist in a tertiary care hospital based on the hypothetical patient information.

AF, atrial fibrillation; CT/CTA, CT and angiography; ICD-10-CA, International Classification of Disease 10th Canadian iteration; MCA-M2, middle cerebral artery, M2 branch, MP, main problem; OP, other problem; TIA, transient ischaemic attack.