British Journal of Radiology 75 (2002),122-126 © 2002 The British Institute of Radiology
Outcomes following unilateral uterine artery embolisation
B McLucas, MD1,
R A Reed4,
S Goodwin2,
A Rappaport5,
L Adler3,
R Perrella2 and
J Dalrymple3
Departments of 1Obstetrics and Gynecology and 2Radiology, University of California at Los Angeles, School of Medicine, Los Angeles, CA, 3Tower-Century Imaging, Century City Hospital, Los Angeles, CA, 4Department of Radiology, Huntington Memorial Hospital, Pasadena, CA and 5Department of Radiology, Long Beach Memorial Hospital, Long Beach, CA, USA
Correspondence: Bruce McLucas, MD, 100 UCLA Medical Plaza, Suite 310, Los Angeles, CA 90095, USA
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Abstract
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Uterine artery embolisation has been described as successful only when both arteries are embolised. However, results in patients with one congenitally absent or previously ligated artery are unknown. Women suffering from symptomatic uterine myomata were treated at a university teaching hospital, a community hospital and an outpatient surgery centre. Retrospective review of patient response to embolisation was assessed by chart review and questionnaire. Uterine and dominant fibroid size response was assessed by comparing pre- and post-embolisation ultrasound examinations. This study analysed three patient groups within the general population: those who underwent unilateral embolisation because of technical failure, those who ultimately underwent bilateral embolisation after initial technical failure and those who underwent unilateral embolisation because of an absent uterine artery. 12 patients underwent unilateral embolisation, 4 of whom underwent this procedure because of an absent uterine artery. Three of these four patients had a congenitally absent uterine artery arising from the internal iliac artery and all three experienced successful outcomes. The fourth patient had a previously ligated internal iliac artery and her symptoms worsened after the procedure. Eight patients had unilateral embolisation due to technical failure. Five of these patients underwent a subsequent procedure during which the contralateral uterine artery was embolised. Four of these five patients had successful outcomes and one was lost to follow-up. Another of the eight patients suffered an arterial injury leading to technical failure, and was lost to follow-up. Of the two remaining patients with unilateral technical failure, only one had a successful outcome. This study concluded that patients who undergo unilateral embolisation for technical reasons should be offered a second embolisation procedure shortly after the initial procedure. Patients with a congenitally absent uterine artery may respond with similar success to those who underwent bilateral embolisation. In contrast, the patient with a previously ligated internal iliac artery failed. The numbers in this study are too small for statistical analysis and subsequent studies should be performed to confirm these findings.
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Introduction
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Uterine artery embolisation (UAE) for uterine fibroids has been shown to control symptoms secondary to myomata [1–4]. It is widely accepted that bilateral embolisation is necessary to achieve success with this procedure. Within our general population of women undergoing UAE, we specifically looked at the outcome of two populations to confirm the importance of bilateral UAE. Patients who underwent unilateral embolisation because the operator was unable to cannulate one of the uterine arteries were considered "technical failures." Patients who had an absent uterine artery were classified as "anatomic failures." Using these definitions three study populations were defined, consisting of: patients who underwent two separate unilateral embolisations (one on each side) owing to technical failure; patients who underwent unilateral embolisation owing to technical failure; and patients who underwent unilateral embolisation owing to previous arterial ligation or an absent uterine artery on one side (Figure 1, 2
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Figure 1. (a) Delayed image from a pelvic angiogram showing retrograde filling of the right uterine artery (arrow) via the left uterine artery (curved arrow). (b) Right common iliac artery angiogram showing the stump of internal iliac artery following previous ligation (arrow).
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Figure 2. (a) Pelvic angiogram demonstrating enlarged right uterine artery (arrow). There is no left uterine artery arising from the internal iliac artery. (b) Delayed image from an oblique angiogram of the left internal iliac artery without demonstration of a uterine artery.
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Materials and methods
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This study was a retrospective review of patients treated between 1996 and 1999. The experiences of women who underwent UAE at a university teaching hospital, a community hospital and an outpatient surgery centre in Los Angeles were reviewed. Many of these patients have been reported in previous studies [5, 6]. All patients suffered from menorrhagia or post-menopausal bleeding. All were offered conventional therapy of either hysterectomy or myomectomy, and were also informed of the lack of long-term studies regarding UAE. The diameter of the largest myoma and the total uterine volume (TUV) [7] were measured, and patients' assessments of their symptoms before UAE [8, 9] were recorded. Patients were questioned again regarding symptom relief 6 months after UAE. All imaging was performed with the same equipment and by the same equipment operator. We defined success after UAE as TUV shrinkage of more than 20% (two standard deviations from a mean shrinkage of 56%) and symptom relief 6 months post UAE.
Three populations were studied. The first included patients who had undergone unilateral embolisation as a result of technical failure followed by subsequent re-embolisation on the contralateral side. The second population included patients who underwent unilateral embolisation for technical reasons and had no contralateral embolisation. The third population included patients who underwent unilateral embolisation because one artery had been previously ligated surgically or because it was congenitally absent (Figure 1, 2
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Results
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During the study period 412 patients underwent UAE and 400 procedures were successfully performed bilaterally. 12 (3%) patients underwent initial unilateral embolisation. Eight of these patients were technical failures. Five of these patients underwent subsequent contralateral embolisation within 2 months. One of these patients was lost to follow-up. One other patient suffered an arterial injury during embolisation, and was lost to follow-up. The two remaining patients declined contralateral embolisation after the initial unilateral procedure.
Four patients were anatomical failures. Three of these patients had a congenitally absent uterine artery while the fourth had a previously ligated hypogastric artery. The outcomes for these subsets of patients are outlined in Table 1.
Of the five patients who required two procedures to accomplish bilateral UAE, four who were available for follow-up had successful outcomes. The other patient showed initial improvement of her clinical symptoms, but a post-UAE ultrasound was not obtained and the patient was lost to follow-up. Two patients underwent unilateral embolisation as a result of technical failure and did not undergo subsequent procedures. Only one of these patients had a successful outcome.
Four patients underwent unilateral embolisation related to anatomical failure. Three of these patients had congenital absence of a uterine artery and experienced successful outcomes. One patient had a previously ligated internal iliac artery. She eventually required hysterectomy for symptomatic fibroids.
In patients who underwent bilateral embolisation, the mean TUV shrinkage was 56%. The four patients available for follow-up who underwent two-part embolisation showed a mean TUV shrinkage of 29%; owing to the small sample population, a level of statistical significance could not be calculated. These patients also reported relief of symptoms. One of the two patients who experienced technical failure but who did not undergo subsequent contralateral embolisation demonstrated TUV shrinkage similar to the group that underwent successful bilateral embolisation. The three patients who were classed as anatomic failures demonstrated TUV shrinkage comparable with the bilateral group, recording a mean TUV shrinkage of 52%, and experienced relief of symptoms. The one patient with anatomic failure due to prior uterine artery ligation suffered uterine enlargement following UAE. It is possible that collaterals to the intrauterine branches develop distal to the point of ligation. This may maintain blood flow to the myomata, making fibroid necrosis following UAE impossible.
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Discussion
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The purpose of UAE is to completely occlude both uterine arteries, thus depriving fibroids of their blood supply. Based on his limited experience with this subset of patients, Ravina et al [10] first postulated that unilateral embolisation of one uterine artery would be unsuccessful in controlling symptoms. Goodwin et al [11] reported one patient who underwent unilateral embolisation whose symptoms did not resolve, thus supporting Ravina et al's hypothesis. Fibroids are supplied by end arterioles of the uterine arteries and, because of this, ischaemic necrosis occurs following bilateral UAE. In cases where patients have bilateral uterine arteries, bilateral UAE is necessary to prevent collateral flow to the fibroid from the contralateral artery following unilateral UAE. The vascular supply to normal uterine tissue is via a rich anastamotic collateral network from the ovarian and vaginal arteries. This protects the normal uterine tissue from ischaemic damage following UAE. Fortunately, in this and other studies involving UAE, ischaemic damage to normal myometrium has not been observed [10]. For embolisation to be effective, selective ischaemia and infarction of the fibroids must occur.
In our series, abdominal aortography was not performed. Because of this, the patients in our series who had only one uterine artery, and who did not have evidence of prior surgical ligation, may or may not have had a uterine arteriole supply arising from the ovarian artery. The high success rate seen in the three patients in this group suggests that, in these patients, the ovarian arteries did not significantly supply the fibroids.
In our series, the technical failure rate was different for each operator performing UAE procedures (0.0–6.0%). This variability can be explained by arterial variability and the experience of the various physicians. The technical failure rate differs in other studies, ranging between 1.6% and 4.3% [4, 12]. Out of 305 women, 13 (4.3%) unsuccessful attempts were reported by Hutchins [12]. In 4 of the 13 women, unilateral embolisation was performed because the collateral arteries thrombosed during catheterization, thus inhibiting polyvinyl alcohol particles from being effective in the procedure. 2 (50%) of the 4 patients who underwent unilateral UAE owing to thrombosis of the opposite uterine artery during catheterization had "excellent" clinical results, but the other two patients had no clinical benefit. Only one uterine artery could be seen in each of five patients on arteriography, and each artery was embolised. Two of these women had a prior myomectomy and it was presumed that the absent artery had been ligated. No results are available. One patient had an anatomic variant in which one uterine artery was a branch of the ovarian artery rather than the internal iliac artery. In two other patients, one uterine artery could not be embolised because of tortuosity. No other series discuss the results of patients with anatomic variants and unilateral embolisation.
Similarly, no other series report experience with "two-step" embolisation after a unilateral failure. Our results encourage us to offer this practice to patients who experienced a technical failure.
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Conclusion
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In the subset of women who underwent unilateral UEA owing to uterine artery absence (without evidence of previous ligation), clinical success rates were equal to those of patients who underwent initial bilateral UAE. The patient with a previously ligated artery experienced failure after UAE. The successful outcomes of the four patients who underwent subsequent contralateral embolisation after initial unilateral technical failure suggest the value of early repeat intervention to achieve bilateral occlusion of the uterine arteries. We are unable to explain the success of our one patient who experienced initial technical failure but did not undergo subsequent contralateral embolisation.
Received for publication April 11, 2001.
Revision received October 9, 2001.
Accepted for publication October 22, 2001.
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References
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Abstract
Introduction
