I63.439

HCC Category Mapping

What This Code Means

A stroke caused by a blood clot blocking a posterior cerebral artery, but the specific side (left, right, or bilateral) is not documented.

Coding Tips

• •Query the provider if laterality can be determined from imaging or clinical documentation
• •Use only when the specific side cannot be identified

Clinical Significance

This code identifies an acute ischemic stroke caused by embolism (a clot originating from a distant source such as the heart or proximal vasculature) lodging in the unspecified posterior cerebral artery. The posterior cerebral artery supplies the occipital lobe, medial temporal lobe, and thalamus. Infarction in this territory affects vision and memory. Accurate coding of the mechanism, artery, and laterality is critical for risk adjustment and tracking stroke subtypes for quality measures and secondary prevention strategies.

Documentation Requirements

• ✓Provider documentation of acute cerebral infarction (stroke) as a confirmed diagnosis, not rule-out or suspected
• ✓Identification of the affected artery as the posterior cerebral artery
• ✓Documentation of laterality (unspecified) supported by clinical findings and/or imaging
• ✓Documentation that embolism is the underlying mechanism, with workup for embolic source (echocardiogram, cardiac monitoring for atrial fibrillation, carotid evaluation)
• ✓Neurological examination findings consistent with the identified vascular territory (e.g., contralateral homonymous hemianopia, visual agnosia, memory deficits, and thalamic sensory loss)
• ✓Brain imaging (computed tomography or magnetic resonance imaging) confirming acute infarction
• ✓Timing of symptom onset to confirm acute presentation
• ✓Documentation of stroke severity (National Institutes of Health Stroke Scale score preferred)
• ✓Treatment administered (thrombolytics, thrombectomy, antiplatelet therapy, anticoagulation)

Commonly Confused Codes