Differences Between the Marginal Artery of Drummond and the Arc of Riolan
The marginal artery of Drummond is a continuous arterial arcade running along the mesenteric border of the colon, while the arc of Riolan is a distinct, less common collateral vessel that connects the left colic branch of the inferior mesenteric artery directly to the superior mesenteric artery through the mesentery. 1
Anatomical Characteristics
Marginal Artery of Drummond
- Runs along the mesenteric border of the entire colon, forming a continuous arterial arcade 1
- Present in virtually all individuals (100% in anatomical studies) 2
- Serves as the primary collateral pathway between the superior mesenteric artery (SMA) and inferior mesenteric artery (IMA) 2
- Located peripherally near the intestinal wall 3
Arc of Riolan
- A more central mesenteric vessel that provides a direct connection between the left colic branch of the IMA and the SMA 1
- Less commonly present (approximately 27.8-50% of individuals) 2, 3
- Located more centrally in the mesentery, away from the intestinal wall 3
- Often becomes enlarged and visible only in pathological conditions involving mesenteric arterial obstruction 1, 4
Clinical Significance
Marginal Artery of Drummond
- Provides the primary collateral circulation to maintain colonic blood flow 2
- Critical for maintaining blood supply to the left colon, particularly at the splenic flexure 5
- Essential consideration during colorectal surgery to prevent ischemic complications 1
- Damage to this artery during surgery may lead to colonic ischemia 1
Arc of Riolan
- Serves as an important indicator of proximal mesenteric arterial obstruction when enlarged 1
- Visible enlargement on arteriography is a significant diagnostic sign of SMA or IMA stenosis/occlusion 1, 4
- Average diameter increases significantly from baseline 1.2 mm to 4.6 mm in SMA obstruction 4
- Can provide critical collateral flow in chronic mesenteric ischemia 6
Radiological Identification
Marginal Artery of Drummond
- Consistently visualized on CT angiography along the mesenteric border of the colon 1, 2
- Maintains a relatively uniform caliber in normal conditions 2
- Should be evaluated preoperatively to plan appropriate surgical resections 2
Arc of Riolan
- Best visualized on anteroposterior aortograms when enlarged 1
- Enlargement is pathognomonic for proximal mesenteric arterial obstruction 1, 4
- Flow direction in this vessel can be upward, downward, or bidirectional depending on which mesenteric artery is obstructed 4
- Mean diameter varies significantly based on underlying pathology (1.2 mm baseline vs. 4.6 mm in SMA obstruction) 4
Surgical Implications
Marginal Artery of Drummond
- Preservation is critical during colorectal surgery to prevent ischemic complications 1
- Damage may lead to compromised blood supply to the left colon 1
- Particularly important when planning resections involving the splenic flexure 2
Arc of Riolan
- Enlargement may influence surgical planning in mesenteric ischemia 1
- Can be a target for endovascular intervention in chronic mesenteric ischemia 6
- Important to identify preoperatively to avoid inadvertent injury during colectomy 2
Common Pitfalls and Considerations
- Terminology confusion is common in the literature - a standardized classification system has been proposed to improve communication between specialists 3
- The arc of Riolan should not be confused with the intermesenteric arcade, which is a separate vascular structure 5
- Preoperative evaluation of both vessels using thin-section CT angiography is recommended before major colorectal surgery 2
- Damage to these collateral pathways during abdominal surgery may precipitate symptomatic intestinal ischemia in patients with pre-existing asymptomatic mesenteric arterial disease 1