What best describes a venous aneurysm?

A venous aneurysm is characterized by a localized saccular or fusiform dilation of a segment of a vein. This means that there is a specific area within the vein that has become abnormally enlarged, often resembling a balloon-like structure. The term "saccular" describes a bulge that is more rounded, while "fusiform" refers to a spindle-shaped dilation. This dilation can result from a weakness in the vessel wall or other underlying conditions.

Understanding the nature of a venous aneurysm is essential for diagnosis and treatment, as it can lead to complications such as thrombus formation, venous stasis, or rupture in severe cases. The other options do not accurately describe an aneurysmal condition. Total obliteration of the venous lumen suggests a complete blockage, while narrowing due to external pressure refers to conditions like venous compression. The presence of multiple small tortuous veins would indicate a different venous pathology, such as a varicose vein or venous malformation. Each of these conditions has distinct characteristics and implications for vascular health, differing significantly from the definition of a venous aneurysm.