Variations of the iliolumbar and ascending lumbar veins.
METHODS
A cadaveric retrospective study.


OBJECTIVE
To verify the variation of tributaries draining into the iliac system at the lumbosacral junction.


BACKGROUND
Special attention to vascular anatomy at the great venous bifurcation during anterior lumbar surgery is needed as more tributaries may increase the rate of operative bleeding. Although important, there have been very few detailed anatomic studies about variations of the ascending and iliolumbar veins. The latter tributary forms a horizontal system draining blood into the iliac vein.


METHODS
A total of 116 formaldehyde-preserved specimens (61 male and 55 female) were studied. All specimens were dissected and simply classified into patterns and subpatterns according to the similar or different tributaries and their entry points.


RESULTS
There were 2 patterns of tributaries: symmetric and asymmetric. More variants were found in the asymmetric group. Each pattern comprising 58 specimens was further classified into 3 subpatterns according to their main tributary trunks. One to 3 tributaries may enter into any trunk of the iliac vein. The most common trunk was the common iliac vein seen in 75.9% of specimens. Draining into the external and internal veins was found in 21.6% and 2.6% of specimens, respectively. One common drainage of the ascending and iliolumbar veins on 1 or both sides was found in 0.9% and > 50% of specimens, respectively (right, 51.7%; left, 56%), whereas 2 or more tributaries were seen in < 50% of specimens (right, 47.4%; left, 43.1%). There was no significant statistical difference among sexes and body sides.


CONCLUSIONS
Draining into the iliac system has a high frequency of variations through a number of tributaries and their entry points. The iliolumbar vein will mainly drain into the common iliac vein with frequently 2 or 3 tributaries, whereas drainage into the external iliac or the internal vein is less often observed.
Department of Medical Services, Center of Excellence in Orthopedics, Lerdsin General Hospital, Bangkok, Thailand.
Sombat
S
Kunakornsawat
Thavat
T
Prasartritha
Patipan
P
Korbsook
Nuttapon
N
Vannaprasert
Rachata
R
Tungsiripat
Tanvaa
T
Tansatit
D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D005260:Female; D006801:Humans; D007084:Iliac Vein / Q000033:anatomy & histology*; D007206:Individuality; D008161:Lumbosacral Region / Q000098:blood supply*; D008297:Male; D012189:Retrospective Studies; D014680:Veins / Q000033:anatomy & histology; D014682:Vena Cava, Inferior / Q000033:anatomy & histology