Major Pelvic Vessels: Anatomical Overview
The prominent pelvic vessels consist of the internal iliac arteries and their branches (arterial system), along with the internal iliac veins, presacral venous plexus, paravesical venous plexus, and ovarian/gonadal veins (venous system).
Arterial System
The internal iliac artery is the dominant arterial supply to the pelvis, arising from the common iliac artery bifurcation 1. This vessel divides into anterior and posterior branches that supply pelvic organs, pelvic wall, and gluteal region.
Key Arterial Branches Include:
- Superior and inferior gluteal arteries - the inferior gluteal artery passes posterior to the sacrospinous ligament with a coccygeal branch that pierces the sacrotuberous ligament 2
- Pudendal artery - passes immediately medial and inferior to the ischial spine (within 0.5 cm), behind the sacrospinous ligament 2
- Uterine artery (in females) - provides primary blood supply to the uterus with anastomoses to the ovarian artery 3
- Ovarian arteries - arise directly from the abdominal aorta and anastomose with uterine vessels 3
- Lumbar arteries - provide collateral pathways 4
Clinical Significance for Trauma:
Only 10-20% of pelvic bleeding is arterial in origin 5. However, when arterial bleeding occurs, concomitant venous bleeding is present nearly 100% of the time 5. The extensive collateral circulation and anastomoses explain why bilateral embolization is often necessary even with unilateral fractures 4.
Venous System
The venous system is far more clinically relevant in pelvic trauma, accounting for 80-90% of hemorrhage 5. The pelvic venous anatomy is complex with extensive collateralization potential 6.
Major Venous Structures:
- Internal iliac veins - main collectors draining to the common iliac veins 7
- Presacral venous plexus - located anterior to the sacrum, a major source of bleeding in sacral fractures 5
- Paravesical venous plexus - surrounds the bladder, bleeds with anterior pelvic ring injuries 5
- Ovarian/gonadal veins - part of the intermediate collateral pathway 6
- Vertebral venous plexuses - provide deep collateral pathways 6
Venous Collateral Pathways 6:
- Deep pathway: lumbar veins, sacral veins, vertebral plexuses
- Superficial pathway: circumflex and epigastric vessels
- Intermediate pathway: gonadal veins, ovarian/uterine plexuses
- Iliofemoral pathways: various collaterals between iliac and femoral systems
Critical Anatomic Features:
The pelvic venous plexuses remain open due to their adhesion to pelvic fascia 7. These vessels are avalvular or have decreased valve presence, allowing bidirectional flow and explaining why venous bleeding is difficult to control with embolization alone 5, 7.
Clinical Pitfall
The most common error is assuming arterial bleeding predominates in pelvic trauma. Since 80-90% of bleeding is venous from presacral/paravesical plexuses and cancellous bone surfaces 5, angioembolization alone has historically resulted in mortality rates exceeding 40% 5. This is why preperitoneal pelvic packing has become essential - it directly addresses the venous bleeding that embolization cannot control 5.