Researchers conducted a retrospective study. For an investigation, they sought to determine if the left common iliac vein (LCIV) anatomy influences the radiologic results after oblique lateral interbody fusion (OLIF) at the L5–S1 level. The study included 52 patients who had OLIF at L5–S1 and were followed for more than a year. According to the difficulty of mobilization, the configuration of LCIV on preoperative axial magnetic resonance imaging of the lumbar spine was classified into 3 types: type I (no need for mobilization), type II (possible easy mobilization), and type III (perhaps difficult mobilization). Anterior/posterior disc heights (ADH/PDH), disc angle (DA), cage migration, cage subsidence, cage position, and fusion rate at L5–S1 were all radiologic measures. Investigators examined the intraoperative and postoperative occurrences linked with OLIF at L5–S1. The LCIV types’ radiologic outcomes were compared. The average age of the participants was somewhere between 62.8 and 9.7 years, with 19 men and 33 women. The average period of follow-up was somewhere between 24.8 and 15.5 months. Type I LCIV architecture was seen in 25 individuals (48.1%), type II in 14 (26.7%), and type III in 13 patients (25.0%). At the latest follow-up, the mean ADH grew from somewhere between 7.0 and 4.7 to somewhere between 16.9 and 4.1 mm (P<0.001), while the mean PDH increased from somewhere between 2.7 and 1.7 to somewhere between 4.9 and 1.6 mm (P<0.001). The mean DA rose (P<0.001) from somewhere between 5.4 and 5.4 to somewhere between 16.9 and 6.5 degrees. There were no significant differences in ADH, PDH, or DA among the LCIV types at the latest follow-up. There were 2 (3.8%) major and 2 (3.8%) minor LCIV injuries, all of which were type III LCIVs. Regardless of the LCIV structure, OLIF at L5–S1 resulted in excellent radiologic results. Type III LCIV patients, on the other hand, had a high rate of intraoperative vascular damage.