Treatments interfering with blood supply to the uterus or fibroids include UAE performed
by an interventional radiologist, or laparoscopic uterine artery occlusion performed
by a gynaecologist. Before discussing these in detail, it is important to
describe the uterine (and therefore fibroid) blood supply.
Uterine and fibroid vascular supply
The uterus has a very rich blood supply through two extrinsic arterial systems, the
uterine and ovarian arteries. Intrinsic uterine arteries consist of ascending
uterine, arcuate, radial and peripherial arteries providing free flow through the uterus.
Fibroids receive their blood supply from the intrinsic arteries, primarily from branches
of the arcuate arteries, and the vessels are located in the pseudo capsule around the
fibroid. The ipsilateral uterine and ovarian arteries are connected via a communicating
(anastomotic) branch. In addition to its primary (uterine artery) and secondary (ovarian
artery) extrinsic blood supply, the uterus has a vast network of lesser known arterial
collaterals. If the blood supply from the right or left uterine artery is occluded, blood
from the left or right artery supplies the myometrium by vascular communicationsthrough the arcuate arteries. If both uterine arteries are occluded, the ovarian arteries
provide a blood supply to the myometrium via the anastomoses. In addition to the primary
and secondary blood flow, the uterus has a vast network of collateral arterial communication
from the aorta, external iliac and femoral artery branch.38
To occlude primary blood flow, uterine artery occlusion must be more distal than
the internal iliac artery, in case occlusion of both internal iliac arteries does not stop
antegrade blood flow.39 As such, it does not cause uterine ischaemia, and the Doppler
flow remains unchanged after bilateral internal iliac artery ligation.40 When bilateral
internal iliac occlusion is performed distal to the posterior division, reverse flow in
the middle haemorrhoidal artery reconstitutes antegrade flow in each uterine artery.
Under these conditions, the antegrade flow in each uterine artery persists and pulse
pressure is damped, resembling a venous system instead of an arterial system; consequently,
it does not cause uterine ischaemia.
Uterine artery embolization
There is a whole chapter devoted to UAE in this issue; therefore, this section will be
brief and is only included for completeness. There can be no doubting the immense
popularity that UAE has gained in the USA and Western Europe over the past decade.
It is performed by highly skilled interventional radiologists, and studies and reports to
date indicate significant efficacy in inducing fibroid shrinkage, improving fibroid-related
symptoms and improving quality of life. A number of issues are still to be resolved, and
definitive studies to compare UAE with myomectomy or MRgFUS are awaited. The key
to success in the provision of a UAE service lies in close collaboration between interventional
radiologists and gynaecologists. This allows for optimal patient selection and
preparation for the procedure, and for appropriate pre- and post-treatment care of
women, since interventional radiologists are not trained in gynaecology, and gynaecologists
cannot perform UAE. Some practitioners insist that women should have endometrial
sampling and/or hysteroscopic imaging prior to UAE, since women with
submucous fibroids may be better served by hysteroscopic resection than UAE.
Others require bacteriological screening and removal of intra-uterine devices prior
to UAE, and all these interventions are within the domain of gynaecologists. In routine
practice in the UK, radiologists rarely have inpatient admitting beds, and the women
would therefore need to be admitted under the care of gynaecologists. When complications
occur, such as chronic vaginal discharge, fibroid extrusion through the vagina,
premature ovarian failure or severe pelvic sepsis, women will present to gynaecologists.
Therefore, the importance of close collaboration between gynaecologists and radiologists
cannot be overemphasized.
Laparoscopic uterine artery occlusion
Perhaps, in part, because of frustration at not being able to perform UAE, some innovative
gynaecologists have developed what is effectively an equivalent procedure to
UAE; laparoscopic bipolar coagulation of uterine arteries and anastomotic sites of
uterine arteries with ovarian arteries.41,42 The peritoneum overlying the external iliac
artery is incised with a T incision between the round ligament and the infundibulo-pelvic
ligament. The iliac vessels are identified, and the retroperitoneal space is developed
(Figure 4). The uterine artery is occluded with an endoclip at the level of the internal
iliac artery. An identical procedure is performed on the opposite side. The collateral arteries between ovaries and uterus (in the utero-ovarial ligament) are coagulated
using bipolar forceps.
In the author’s institution, 46 premenopausal women with symptomatic fibroids
were studied, of whom 24 underwent UAE and 22 underwent laparoscopic occlusion
of the uterine arteries. The picture blood assessment scores were reduced by 50%
in both groups after 6 months, and uterine volume was reduced by 35–40% in both
groups. Interestingly, less post-treatment pain, less nausea and shorter hospital stay
were reported in the laparoscopic uterine artery occlusion group compared with
the UAE group. On the downside, more women in the laparoscopic occlusion group
experienced heavy menstrual bleeding at 6 months compared with the UAE group. It
can be tentatively concluded that laparoscopic uterine artery occlusion therapy is
a promising new method for treating fibroid-related symptoms, with outcomes at least
comparable to UAE. However, it is recognized that the numbers in this study were
small, and there is a need for a randomized trial of the two procedures before definitive
conclusions can be made.