Portal vein aneurysms (PVAs) are rare, and there is limited evidence to guide management when they are identified. In this case report, we describe the incidental finding of a 3.5 cm PVA in an otherwise healthy female in her early 20s after surgery for appendicitis. A thrombophilia screen was conducted, revealing the patient also had Factor V Leiden deficiency. After reviewing the available literature, a conservative approach was undertaken, and the aneurysm has remained stable over 4 years of serial imaging without thrombotic or other complications.