Introduction: Congenital hypoplasia or aplasia of the internal carotid artery (ICA) is believed to affect less than 0.01% of the population, with fewer than 200 unilateral and 30 bilateral cases reported in the literature. While often asymptomatic, they have been associated with stroke, transient ischemic attack (TIA), and other neurovascular pathologies.

Case Report: We describe a 33-year-old 28 weeks pregnant female with a history of patent foramen ovale (PFO) and ischemic stroke in the right middle cerebral artery (MCA) distribution three years prior who experienced new onset transient right upper extremity weakness and numbness. Duplex sonography revealed bilateral hypoplasia of the internal carotid arteries (HICA), confirmed by CT and MR angiography of the head and neck.

Discussion: To our knowledge, this is the first reported case of bilateral HICA with concurrent PFO and pregnancy presenting with TIA. All three conditions are associated with stroke and TIA. HICA should be included in the differential diagnosis of neurologic deficit despite its rarity.