Anatomy, Abdomen and Pelvis, Internal Iliac Arteries

The internal iliac artery supplies the gluteal muscles, pelvic viscera, perineum, and pelvic walls. The anterior division is more involved with territorial blood supply to the pelvic viscera, and the posterior division provides blood flow to the gluteal region and body wall.[4]

One must be aware of the several types of anatomical variations that may present during a surgical procedure. The first significant variance is that the internal iliac artery origin varies and depends on several factors such as the length of the common iliac artery and when the internal iliac artery bifurcates. It can be at the level of the L5-S1 and S1 intervertebral disk and anterior to the sacroiliac joint.[4]

The obturator artery (OA) can arise from:

• the posterior branch of the internal iliac artery
• the inferior epigastric artery
• the inferior vesical artery

Iliolumbar artery can come directly from the trunk of the internal iliac artery.[4]

• When accessing the internal iliac artery in a female one must cut the pelvic peritoneum which is continuous with the broad ligament to visualize the retroperitoneal area. In the retroperitoneum, the internal iliac artery and the other great vessels of the abdomen are visible.[1]
• Two vessels that can give some blood supply to the femoral head is the piriformis branch of the inferior gluteal artery and the obturator artery via the foveal artery. Many anatomical variations occur with the obturator artery with the most common one being the corona mortis (crown of death).[7]
• The corona mortis is an anastomotic branch between the inferior epigastric and obturator vessels in the obturator canal. The other variation involves an accessory obturator artery arising from the external iliac artery and forming a connection with the obturator artery coming off of the internal iliac artery. The accessory OA can traverse over the superior pubic ramus creating a risk of injury during mesh attachment for hernia repair.[8] Another significance of the corona mortis during surgery is that compression of the internal iliac will not wholly stop bleeding from this anomalous artery since it is also receiving blood flow from the external iliac artery. However, compression of the internal iliac artery can still be used to control the contribution of blood flow that is coming from the IIA to the corona mortis.[9]
• During surgery in the pelvis, another critical vessel to be mindful of is the location of the ureter which is located at the medial aspect of the internal iliac artery. The space between the ureter and the IIA is known as the para-rectal space. During a hysterectomy, the surgeon needs to be mindful when ligating the uterine artery (a branch of IIA) because the ureter passes beneath this artery and is at risk for injury.[1]
• It is essential to attempt to ligate the internal iliac artery distal to the posterior branch. Experience shows that proximal ligation of the internal iliac artery can result in claudication of buttocks and also necrosis.[4]

In acute situations involving the pelvic region knowledge of the level of the bifurcation of the common iliac artery and the level of division of the internal iliac artery is of paramount importance. Unilateral or bilateral ligation of the internal iliac artery can be lifesaving in a variety of patients, such as massive postpartum hemorrhage, hemorrhage after a vaginal and abdominal hysterectomy, massive broad ligament hematoma, cervical carcinoma, and retroperitoneal bleeding following a pelvic fracture.[4]

When trying to control a bleed in the pelvis, bilateral ligation of the internal iliac arteries will reduce the pelvic arterial blood flow by 49%.  Collateral arterial circulation will make up for the blood that was previously being supplied by the internal iliac artery. The main artery that collateral circulation comes from is the deep femoral artery. [2] Various anastomoses aid in re-vascularizing the internal iliac artery area such as superior gluteal artery and lateral femoral circumflex artery, obturator artery and medial femoral circumflex artery. In females, blood flow to the uterus via the ovarian artery and after bilateral internal iliac artery ligation reproduction potential is not affected, and it is still possible to have term pregnancies in many cases.[2]

Knowing the anatomical course of the ureter is vital because during acute situations to control hemorrhage damage to the ureter can occur. The ureter which is usually laying on the surface of the internal iliac artery requires identification before ligation performed.[4]

An anomalous origin of the obturator artery from the posterior division becomes vital because if damage occurs to the anterior branch of the internal iliac artery the blood supply to the head of the femur would not be affected.[4]