A fetal posterior cerebral artery (fPCA), also referred to as a fetal PCA, is an anatomical variant of the origin of the Posterior cerebral artery. In this variant, the primary blood supply to the posterior cerebral artery is provided by the Internal carotid artery rather than by the vertebrobasilar territory. A distinction is made between a complete fetal PCA and a partial fetal PCA[^2]. In a complete fetal PCA, the PCA arises directly from the ICA without a connection to the Basilar artery. In a partial fetal PCA, a connection to the basilar artery is still present.
Definition
A fetal PCOM variant is defined as a PCOM artery that has the same caliber as the P2 segment of the PCA and is associated with a hypoplastic P1 segment[^3].
Epidemiology
A fetal PCOM is present in approximately 4-46 % of patients[^1] [^3]. A bilateral fetal PCOM variant can be found in 1-9 % of patients[^3].
Imaging
A fetal PCOM can be visualized on MR angiography or digital subtraction angiography.
Clinical relevance
Patients with a fetal PCA may become symptomatic in the setting of impaired blood flow in the internal carotid artery, as in PCA ischemia.