Ring formation of the internal iliac artery.

We observed an arterial ring communicating the superior and inferior gluteal arteries in the left half of the pelvis of an 88-year-old male. Although many previous studies have shown variations in the internal iliac artery, there has been no literature describing the fenestration. Therapeutic embolization is commonly performed for intractable bleeding in pelvic region. Surgeons should be aware of the arterial ring formation because of possible danger in the intravascular treatments. In patients with similar arterial rings, embolization of the anterior trunk of the internal iliac artery could be insufficient when blood runs through the circle of the arterial ring.