I63.333

HCC Category Mapping

What This Code Means

A stroke caused by blood clots blocking both the right and left posterior cerebral arteries simultaneously, affecting the back portions of both sides of the brain.

Coding Tips

• •Bilateral coding requires explicit documentation that both posterior cerebral arteries are affected
• •Verify imaging or clinical documentation supports bilateral posterior circulation involvement

Clinical Significance

This code identifies an acute ischemic stroke caused by thrombosis (in-situ clot formation) of the bilateral posterior cerebral artery, requiring precise documentation of the clot mechanism. 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 (bilateral) supported by clinical findings and/or imaging
• ✓Documentation that thrombosis (in-situ clot formation) is the underlying mechanism, typically supported by vascular imaging such as computed tomography angiography or magnetic resonance angiography
• ✓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