Objective To explore the distribution of iliac vessels in the anterior lower lumbar spine using
CT angiography，and to provide vascular anatomical references for anterior lower lumbar surgery. Methods Select
100 male and 100 female patients who underwent abdominal CT angiography at Guizhou Provincial People′s Hospital
from June 2016 to November 2018 for observation and measurement research；（1）Observe and record the distribution
of the bifurcation points of the abdominal aorta and the confluence points of the common iliac vein；（2）Measure
the distance from the vertex of the angle between the left common iliac vein and the right common iliac artery to
the upper edge of the L5⁃S1 intervertebral space ，and the distance between the left common iliac vein and the
inner edge of the right common iliac artery at the upper and lower edges of the L5 ⁃S1 intervertebral space. Results （1）64% of the L4 vertebral body is flat at the bifurcation point of the abdominal aorta. The confluence point of the
common iliac vein accounts for 42% of the L4 vertebral body and 40% of the L4⁃5 intervertebral space.（2）Abdominal
aortic bifurcation angle：（51.01 ± 9.24）° for males，（50.51 ± 7.92）° for females；The confluence angle of the
common iliac vein is（58.82 ± 11.81）° for males and（62.47 ± 12.46）° for females；The angle between the left
common iliac vein and the right common iliac artery is（64.92 ± 12.07）° for males and（68.73 ± 13.87）° for females.
（3）When the confluence point of the common iliac vein is level with the L4 vertebral body，L4 ⁃ 5 intervertebral space，and L5 vertebral body：① The distance from the vertex of the angle between the left common iliac vein and
the right common iliac artery to the upper edge of the L5 ⁃S1 intervertebral space is（26.51 ± 8.11）mm，（16.18 ±
6.70）mm，and（7.82 ± 4.26）mm，respectively；② The distances between the left common iliac vein and the
medial edge of the right common iliac artery from the L5⁃S1 intervertebral space are（32.52 ± 9.95）mm，（28.63 ±
11.48）mm，and（16.27 ± 7.71）mm，respectively The distance between the left common iliac vein and the inner
edge of the right common iliac artery at the lower edge of the L5⁃ S1intervertebral space is（43.88 ± 9.86）mm，
（41.55 ± 11.05）mm，and（33.17 ± 9.40）mm，respectively. ④ The area of the“iliac vascular triangle”is
（486.32 ± 246.26）mm2
，（263.94 ± 178.47）mm2
，and（85.49 ± 71.45）mm2
，respectively The surgical windows
for the L5⁃S1 intervertebral space are（496.98 ± 114.48）mm2
，（488.89 ± 127.69）mm2
，and（344.32 ± 166.63）mm2
，
respectively. Conclusion （1）There are significant anatomical changes at the bifurcation point of the abdominal
aorta and the confluence point of the common iliac vein；The bifurcation point of the abdominal aorta is mostly flat
on the L4 vertebral body，and the confluence point of the common iliac vein is mostly flat on the L4 vertebral body
and the L4⁃5 intervertebral space.（2）When the confluence point of the common iliac vein is level with the L4 verte⁃
bral body，there is sufficient vascular safety zone in front of the lower lumbar spine for surgical operation；When
the confluence point of the common iliac vein is located in the L4⁃5 intervertebral space，there is a certain vascular
safety zone in front of the lower lumbar spine for surgical operation；When the confluence point of the common iliac
vein is flat on the L5 vertebral body，the safety zone of the anterior blood vessels of the lower lumbar spine cannot
meet the surgical requirements at this time.（3）When the confluence point of the common iliac vein is level with
the L4 vertebral body and the L4⁃5 intervertebral space，there is sufficient surgical vascular safety zone in the anteri⁃
or L5⁃S1 intervertebral space，but the vascular safety zone is gradually reduced. Preoperative CT angiography exami⁃
nation to clarify the vascular safety zone is helpful for surgical safety.
