The First Rib as a Fluoroscopic Marker for Subclavian Vein Access

Purpose To determine whether the anatomic relationship between the subclavian vein (SCV) and the first rib is sufficiently constant to allow safe and reproducible fluoroscopically guided SCV puncture. Materials and Methods Forty-four subclavian venograms were obtained from 42 consecutive adult patients. Position and width of the SCV crossing over the first rib were recorded by using radial coordinates. Based on this anatomic study, 42 SCV access procedures were performed with use of the first rib as a fluoroscopic marker. Technical success, complications, number of 21-gauge needle passes, physician experience, and patients’ body habitus were recorded. Results Mean angular position of SCV/first rib crossover was 94.7° (standard deviation [SD], 7.42°). Mean radial width of the SCV was 14.9° (SD, 3.1°). On 25 of the 44 subclavian venograms (60%), the SCV/first rib crossover lay within the 90°–99° segment, and on 36 of 44 (82%) it lay within the 85°–104° segment. Technical success in accessing the SCV was 100% (42 of 42 procedures). Two minor complications involved subclavian artery puncture with the 21-gauge needle without sequelae. The mean number of needle passes required was 2.86 (median, 1.7). There was no correlation between needle passes and patients’ body habitus or physician experience. Conclusion The SCV is reliably constant in its relation to the first rib. The first rib alone provides a reliable fluoroscopic marker for safe SCV access without the need for ultrasound guidance or peripheral contrast material administration.