The two hypogastric (internal iliac) arteries and the inferior mesenteric artery (IMA) together supply blood flow to the pelvis, including the buttocks, left colon, and terminal spinal cord. It is a near-absolute requirement that at least one of these three vessels be preserved. The IMA is frequently the least important source of pelvic blood flow; every effort should be made, however, to preserve at least one hypogastric artery. Within these guidelines, essentially any other vessel can be ligated with impunity.
Abdominal and pelvic vasculature
1 Femoral artery and vein
3 Inferior mesenteric artery
5 Renal artery and vein
8 Common iliac artery and vein
9 Internal iliac artery and vein
The anatomy of the lower abdominal, pelvic and groin vasculature is illustrated in Figures 1 and 2. Remember that arteries are thick-walled, resistant to tearing, and easier to repair than veins. Veins, by contrast, are thin-walled, do not hold their shape, and tear easily.
Vasculature of the groin
1 Saphenous vein
4 External iliac vein
7 Superficial femoral artery
8 Deep femoral artery (profunda)
The veins tend to lie behind the arteries (Figure 3). This is critically important at the region of the aortic bifurcation and proximal iliac arteries, where dissection behind the arteries (circled area) or within the aortic bifurcation can easily precipitate massive, life-threatening venous hemorrhage.
In general, trying to control an injury directly is counterproductive. For arterial injuries, proximal and distal control at sites remote from the bleeding are required (Figure 4). Direct clamping can sometimes be problematic, for example in the hypogastric arteries. In these cases control can be accomplished by intraluminal balloon catheter occlusion. For venous injuries, direct pressure or packing while the situation is sorted out is much more useful than trying to see the injury or control it with a clamp. Direct manipulation with rigid instruments will often extend the tear and worsen the situation.
For vessel repair, autologous tissue is usually preferred (especially in a potentially infected field), although this 'rule' must often be violated. An option in unfavorable situations is to route a graft through an
Aortic bifurcation—a danger area (circled)
2 Vena cava
Control at sites remote from the bleeding is essential for arterial injuries unviolated, 'extra-anatomic' plane. If vessel resection is planned or possible, include a source of autogenous vein (e.g. a leg, circumferentially prepared) in the surgical field (Figure 5).
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.