Fetal posterior cerebral artery

Last revised by Dr Raymond Chieng on 05 Aug 2022

A fetal (origin of the) posterior cerebral artery is a common variant in the posterior cerebral circulation, estimated to occur in 20-30% of individuals 2.

The posterior communicating artery (PCom) is larger than the P1 segment of the posterior cerebral artery (PCA) and supplies the bulk of the blood to the PCA 4. Meanwhile, the type of PCom supplying the PCA is also called fetal PCom 5. If bilateral, the basilar artery is significantly smaller than normal. 

The term is typically used to refer to the situation where the PCom is larger than the P1. However, variation in usage abounds.

The P1 can be small (hypoplastic) or absent. The significance is in the stroke pattern, as the PCA is practically a part of the anterior circulation. Additionally, a larger PCom with an existing P1 allows for collateral circulation.

In cases of non-fetal PCA, the PCom lies superomedial to the oculomotor nerve, whereas in cases of fetal PCA, it lies superior or superolateral to it.

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Cases and figures

  • Figure 1
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  • Case 1
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  • Case 2
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  • Case 3 : fetal PCA with para PCom aneurysm
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  • Case 3: infarction consequences of fetal PCA
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  • Case 4
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  • Case 5
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  • Case 6
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  • Case 7: bilateral fetal Pcomms
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  • Case 8: left
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