Sunday, December 27, 2009

Ovarian Artery Variants

The ovarian arteries most commonly (80%-90% of cases) arise anteromedially from the abdominal aorta a few centimeters inferior to the origin of the renal arteries. They may be difficult to visualize on angiography due to their small caliber (< 1 mm). If they are seen, they demonstrate a characteristic corkscrew appearance. The ovarian arteries may also arise from the renal, lumbar, adrenal, or iliac arteries.

In 40% of cases, the ovaries are supplied solely by the ovarian arteries. In about 55% of cases, both the uterine and ovarian arteries supply the ovaries, while in about 5% of cases, the uterine arteries alone supply the ovaries.

The last variant may be due congenital absence of the ovarian artery, occlusive lesions at the level of the ovarian artery or the aorta, or ovarian abnormalities (e.g., tumor or inflammatory conditions causing neovascularization). If such a case is identified on angiography, a coexistent ovarian abnormality must be excluded.

Another source of variability important in uterine fibroid embolization (UFE) is the different anastomotic connections between the uterine and ovarian arteries, which may be seen in up to 30% of cases.
  • Type I: There is flow from the ovarian artery to the uterus through anastomoses with the tubal branch of the uterine artery. Following UFE, the ovarian supply is not likely to be a source of procedural failure.
    • Type Ia: Flow in the tubal artery is toward the uterus, without evidence of retrograde reflux to the ovary.
    • Type Ib: Flow in the tubal artery is toward the uterus, but there is evidence of retrograde reflux to the ovary. Injection of embolic particles into the uterine artery may cause reflux into the tubo-ovarian segment and may cause embolization of the ovary.
  • Type II: There is a direct blood supply to a fibroid from the ovarian artery without prior connection to the uterine artery. Following UFE, the fibroid may continue to be supplied, and the ovarian artery can be a cause of procedural failure.
  • Type III: The dominant blood supply to the ovary is from the uterine artery (see also above). This is important in UFE, as there is a high likelihood of ovarian artery embolization.


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