Common iliac artery

The common iliac artery is a major paired blood vessel in the human body that serves as the principal conduit of blood from the abdominal aorta to the pelvis and lower limbs. Its anatomical position and branching pattern make it clinically important in both vascular health and surgical interventions.

Introduction

The common iliac artery represents the primary division of the abdominal aorta at its terminal end. It plays a crucial role in supplying oxygenated blood to the pelvis, abdominal wall, and lower limbs. Knowledge of its anatomy, branches, and relations is fundamental for clinicians, surgeons, and radiologists, as this vessel is commonly involved in vascular pathologies such as aneurysms and occlusive disease.

This section will provide an overview of the artery’s anatomical structure and its clinical relevance.

Anatomy of the Common Iliac Artery

Origin and Course

The common iliac arteries are formed by the bifurcation of the abdominal aorta at the level of the fourth lumbar vertebra. Each artery runs inferolaterally toward the pelvic brim, coursing along the medial border of the psoas major muscle. At the level of the sacroiliac joint, each artery divides into the external iliac and internal iliac arteries.

Length and Diameter

The average length of the common iliac artery ranges between 4 to 7 cm, with a diameter of approximately 1 cm. These values can vary slightly depending on age, sex, and body habitus. The artery’s dimensions are clinically significant for diagnostic imaging and endovascular interventions.

Relations

The common iliac artery is related to several important anatomical structures, which are essential to recognize during surgical and radiological procedures.

• Anterior relations: Peritoneum, loops of small intestine, ureter in certain segments.
• Posterior relations: Vertebral column, psoas major muscle, sympathetic trunk.
• Lateral relations: Common iliac vein, psoas muscle.
• Medial relations: Contralateral common iliac artery at the point of aortic bifurcation.

Branches of the Common Iliac Artery

Terminal Branches

The common iliac artery terminates by dividing into two main branches at the level of the sacroiliac joint. These branches are responsible for carrying blood to the pelvis and lower limbs.

• External iliac artery: This branch continues along the pelvic brim and passes beneath the inguinal ligament to become the femoral artery. It supplies the lower limb and also gives off branches to the abdominal wall.
• Internal iliac artery: This branch descends into the pelvis to provide vascular supply to pelvic organs, the gluteal region, and perineum through numerous divisions.

Minor Branches

Although the common iliac artery primarily ends in the external and internal iliac arteries, small collateral branches may occasionally arise. These branches usually supply nearby lymph nodes, connective tissue, or adjacent veins. However, their presence is not constant and varies among individuals.

Variations

Anatomical Variations

Several anatomical variations of the common iliac artery have been described in medical literature. These variations may include differences in the level of bifurcation, asymmetry between the left and right arteries, or atypical branching patterns. Rarely, the common iliac artery may give rise to aberrant branches such as accessory renal or iliolumbar arteries.

Clinical Significance of Variations

The presence of anatomical variations is highly relevant in clinical practice. Variations can influence the approach during vascular surgeries, endovascular procedures, and organ transplantation. For example, an unusually high bifurcation may complicate stent placement or grafting. Additionally, knowledge of aberrant branches is crucial to prevent accidental injury during pelvic surgeries.

Blood Supply and Distribution

Pelvic Organs

The common iliac artery, through its internal iliac branch, provides essential blood supply to the pelvic viscera. This includes the urinary bladder, rectum, reproductive organs, and portions of the ureter. The pelvic blood flow is vital for the functioning of these organs, and disturbances can lead to significant clinical consequences.

Lower Limb

The external iliac artery, a terminal branch of the common iliac, is the primary source of blood supply to the lower limb. After passing beneath the inguinal ligament, it becomes the femoral artery and gives rise to multiple branches that nourish the thigh, leg, and foot. Adequate perfusion of the lower limb depends on the integrity of the common iliac and its branches.

Abdominal Wall

Through its branches, particularly the external iliac artery, the common iliac indirectly contributes to the vascularization of the anterior abdominal wall. The inferior epigastric and deep circumflex iliac arteries, arising from the external iliac, play a significant role in supplying the abdominal musculature and overlying skin.

Relations to Venous and Lymphatic Structures

Common Iliac Veins

The common iliac artery is closely related to the common iliac veins, which lie posteromedially. This relationship is clinically important, as any arterial enlargement, such as in an aneurysm, can compress the adjacent vein and lead to venous obstruction or thrombosis.

Lymph Nodes and Lymphatic Pathways

Numerous iliac lymph nodes are positioned around the common iliac artery. These nodes form part of the major lymphatic drainage pathways of the pelvis and lower limb. They are frequently evaluated in cases of malignancy and may become enlarged in infections or metastatic disease.

Relations with Ureter

The ureter crosses anteriorly over the common iliac artery near its bifurcation. This anatomical relationship has surgical significance, particularly during procedures involving ureteric reimplantation, vascular repair, or pelvic surgery, as inadvertent injury to either structure can occur.

Embryological Development

Developmental Origin

The common iliac arteries develop from the remodeling of the primitive dorsal aorta and its segmental branches during embryogenesis. Initially, blood supply to the lower limb buds arises from the axial artery, a continuation of the dorsal aorta. As development progresses, the iliac system forms through the reorganization of these vessels, ultimately giving rise to the definitive common, internal, and external iliac arteries.

Congenital Anomalies

Congenital anomalies of the common iliac artery are rare but may include abnormal origin, duplication, or agenesis. These anomalies can sometimes be detected prenatally or during imaging for unrelated conditions. Clinically, such anomalies may predispose patients to vascular insufficiency or complicate surgical and interventional procedures.

Imaging of the Common Iliac Artery

Ultrasound

Doppler ultrasound is a noninvasive method commonly used to evaluate blood flow within the common iliac artery. It is useful for detecting stenosis, occlusion, and aneurysmal dilatation. Its portability and safety make it a first-line investigation.

CT Angiography

CT angiography provides detailed visualization of the common iliac artery and its branches. It allows assessment of arterial caliber, wall irregularities, and pathological conditions such as aneurysms or thrombosis. The three-dimensional reconstruction capability is particularly valuable for surgical planning.

MRI Angiography

Magnetic resonance angiography is a radiation-free alternative that offers high-resolution images of the iliac arteries. It is especially useful in patients with contraindications to iodinated contrast agents used in CT. It can provide both functional and structural information.

Conventional Angiography

Despite the advent of advanced imaging modalities, conventional angiography remains the gold standard for evaluating vascular anatomy and pathology. It allows both diagnostic assessment and therapeutic interventions, such as angioplasty or stent placement, in the same setting.

Pathologies Involving the Common Iliac Artery

Atherosclerosis

Atherosclerosis is the most common pathology affecting the common iliac artery. Progressive plaque buildup leads to narrowing of the arterial lumen, resulting in reduced blood flow to the pelvis and lower limbs. Clinically, this may manifest as claudication, ischemic rest pain, or tissue loss in severe cases. Imaging is often required to confirm the diagnosis and assess the extent of disease.

Aneurysms

Aneurysmal dilatation of the common iliac artery, either isolated or in association with an abdominal aortic aneurysm, poses a risk of rupture. Risk factors include advanced age, male sex, smoking, and hypertension. Symptoms are often absent until the aneurysm reaches a critical size or causes compression of adjacent structures.

Thrombosis and Embolism

Acute thrombosis or embolic occlusion of the common iliac artery can lead to sudden onset of ischemia in the lower limb. Patients may present with pain, pallor, pulselessness, and paralysis. Prompt recognition and treatment are essential to prevent irreversible tissue damage.

Trauma and Iatrogenic Injury

The common iliac artery may be injured in pelvic fractures, penetrating trauma, or during surgical and interventional procedures. Such injuries can result in hemorrhage, pseudoaneurysm formation, or arteriovenous fistula. Rapid diagnosis and repair are critical in preventing life-threatening complications.

Compression Syndromes

Occasionally, the common iliac artery can be compressed by surrounding structures such as the psoas muscle or overlying veins. A notable example is May-Thurner syndrome, where the right common iliac artery compresses the left common iliac vein, predisposing to venous thrombosis.

Clinical Significance

Symptoms and Signs of Arterial Disease

Disease involving the common iliac artery can present with a spectrum of clinical features, ranging from asymptomatic incidental findings to severe limb ischemia. Symptoms may include hip or thigh claudication, rest pain, and in advanced cases, nonhealing ulcers or gangrene.

Risk Factors and Predisposing Conditions

Several risk factors contribute to pathology of the common iliac artery, including smoking, diabetes mellitus, hypertension, hyperlipidemia, and advanced age. Genetic predisposition and systemic vascular disease also increase susceptibility.

Complications

If left untreated, common iliac artery disease can lead to severe complications such as limb loss, rupture of aneurysms, or systemic embolization. Secondary effects may include venous obstruction, ureteric compression, or pelvic ischemia, highlighting the artery’s central clinical importance.

Surgical and Interventional Procedures

Endovascular Techniques

Endovascular approaches are frequently employed in the management of common iliac artery disease due to their minimally invasive nature and favorable recovery profiles. These techniques are guided by imaging and performed through percutaneous access.

• Angioplasty: Balloon angioplasty involves dilating a stenotic segment of the artery to restore blood flow. It is often used in cases of atherosclerotic narrowing.
• Stenting: Placement of metallic stents provides structural support to keep the arterial lumen open. Stents may be drug-eluting or bare-metal, chosen based on clinical context.

Open Surgical Approaches

Open surgery may be indicated when endovascular methods are not feasible or when large aneurysms are present. Procedures include direct repair, ligation, or replacement with synthetic grafts. These interventions are more invasive but may provide long-term durability.

Bypass Grafts

Bypass grafting is employed to reroute blood flow around a diseased or obstructed segment of the artery. Grafts may be autologous, such as the saphenous vein, or synthetic. Aortoiliac or iliofemoral bypasses are common options depending on the extent of disease.

Complications of Procedures

Both endovascular and open surgical procedures carry potential risks. Complications may include arterial dissection, thrombosis, embolization, graft occlusion, infection, or bleeding. Long-term surveillance is essential to detect recurrence or new vascular lesions.

References

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