Ultrasound Mapping of the Anatomical Relationship Between the Right Internal Jugular Vein and Carotid Artery

This prospective observational study will describe the anatomical relationship between two major blood vessels on the right side of the neck: the internal jugular vein and the common carotid artery. These vessels lie close together, and their relative positions are relevant when placing a central venous catheter. The study will enroll 200 adults undergoing elective cardiac surgery at Ankara Bilkent City Hospital who require right internal jugular vein catheterization as part of their routine care. A single ultrasound image will be recorded for each participant under standardized conditions after general anesthesia and before catheter placement. Computer-assisted image analysis will determine the angular position of the artery around the center of the vein on a 0°-360° scale. The study will describe the distribution of these angles and their frequencies within eight anatomical sectors. The findings may provide a more detailed quantitative description of neck vascular anatomy and support future research on ultrasound-guided central venous access. Participation will not alter routine anesthesia or catheterization management.

Inclusion Criteria: * Age 18 years or older. * Scheduled for elective cardiac surgery. * Planned to undergo general anesthesia. * Scheduled for right internal jugular vein catheterization as part of routine clinical care. * Willing to participate and provide written informed consent. Exclusion Criteria: * Previous major surgery or marked anatomical deformity in the right neck region. * Known right internal jugular vein thrombosis or occlusion, or a marked cervical vascular anomaly. * Local pathology, a wound, or a dressing that prevents ultrasound assessment. * Emergency surgery. * Inability to safely achieve the standardized study position. * Inability to reliably identify vessel boundaries on the ultrasound image or failure to meet the standardization criteria. * Refusal to participate in the study.