*: Dr W.J. Walker, Department of Diagnostic Radiology, The Royal Surrey County Hospital, Egerton Road, Guildford, Surrey GU2 7XX, UK
Objective To assess the reduction in size of fibroids following uterine artery embolisation and to analyse women's views of the success of treatment.
Design An uncontrolled case series of 114 consecutive women who underwent uterine artery embolisation for the treatment of fibroids over two years.
Setting The Diagnostic and Interventional Radiology Department at The Royal Surrey County Hospital, Guildford, UK.
Methods Bilateral uterine artery embolisation was performed for the treatment of symptomatic fibroids. Magnetic resonance imaging was carried out before and six months following embolisation. Women completed outcome questionnaires following their treatment.
Main outcome measures The sites, imaging signal characteristics and percentage reduction in the volume of three dominant fibroids were determined from the magnetic resonance scans. Outcome was measured by questionnaire. Women were asked whether their symptoms resolved completely, improved, remained unchanged or deteriorated.
Results One hundred and sixty-five fibroids of 114 women (mean age 42) were analysed. Forty-five percent of women had complex fibroid masses and 50% had fibroids ≥8.5cm in diameter. The median reduction in the fibroid volume was 58%. The median reduction of the volume of complex fibroid masses, submucous fibroids, fibroids ≥8.5cm and fibroids with high and low signal on T2 weighted sequences were 58%, 63%, 50%, 62% and 51%, respectively. Ninety-one percent of the women's symptoms had resolved or improved following embolisation.
Discussion The majority of women were satisfied with their outcome. We have shown that uterine artery embolisation is a successful treatment for symptomatic fibroids of all types, sizes and signal characteristics.
Uterine fibroids are the most common benign tumour of the female pelvis and are responsible for symptoms such as pelvic pain, menorrhagia, urinary frequency and compressive bowel symptoms in approximately 20%–50% of women1. In addition, 41% of pregnancies associated with fibroids result in miscarriage2. There is now a trend towards more conservative treatment of benign uterine disease, avoiding hysterectomy that has a significant morbidity and mortality3–6.
Uterine artery embolisation is a relatively recent minimally invasive alternative to hysterectomy for the treatment of symptomatic fibroids7–11. There are several small case series which have a success rate of approximately 90%7–11. The aim of our study was to measure the amount of fibroid shrinkage after uterine artery embolisation using magnetic resonance imaging and to determine whether the type of fibroid, its size and signal characteristics can be used to predict the degree of shrinkage. The outcome was also assessed by the women using a questionnaire.
Uterine artery embolisation was performed by W.J.W. using a standard technique. The woman was sedated with a combination of fentanyl 100mcg and midazolam 10mg together with an antiemetic metoclopramide 10mg. A sheath was introduced into the right common femoral artery following administration of local anaesthetic, 10mL lignocaine 2% and both uterine arteries were catheterised from one side using a loop technique to catheterise the ipsilateral uterine artery. A number 4 French-gauge catheter (Cordis, Johnson & Johnson, UK) was used to gain access to the origin of the uterine artery. A μ-catheter (Fastracker 325, Boston Scientific Ltd, UK) was then advanced through the vessel. Embolisation was performed with polyvinyl alcohol particles (Boston Scientific Ltd, UK), mainly 355–500 micrometers in diameter, and was followed in all cases by the insertion of fibre platinum coils (Boston Scientific Ltd, UK) with a diameter of 0.2mm–0.5mm, to occlude or reduce flow in both uterine arteries.
Magnetic resonance imaging was carried out using a Phillips 1 Tesla Gyroscan (Best, Holland). Sagittal and axial T2 turbo spin echo sequences (field of view 360mm, number of slices 24, slice thickness 4mm and gap 2mm) and axial T1 weighted spin echo sequences (field of view 375mm, 24 slices, 4mm slice thickness and 2mm gap) were performed through the pelvis. Scans were performed before and six months following the uterine artery embolisation. In some women only T2 weighted scans were carried out. The volumes of the three dominant fibroids were calculated by G.W. by measuring the maximal anterior–posterior, transverse and sagittal diameters and multiplying the product of these by 0.5233 before and after uterine artery embolisation. The percentage reduction of the volume of the fibroids was then determined in each case.
The data from unselected consecutive women who had magnetic resonance scans at six months were analysed. The sites of the fibroids and the magnetic resonance imaging signal characteristics were documented and associated with the outcome of the uterine artery embolisation. The outcome was measured by questionnaire, where the woman was asked whether her symptoms had resolved completely, improved, remained unchanged or had become worse. The questionnaires were completed at six weeks and at three, six, 12, 18 and 24 months following uterine artery embolisation. The women were also asked whether they would have this treatment again and whether they would recommend it to others. The case notes were reviewed to document uterine surgery before and after uterine artery embolisation.
The characteristics of the women are shown in Table 1. Complex fibroid masses were classified where the site of origin of the fibroids could not be defined. Examples of the magnetic resonance features of the fibroids before and after uterine artery embolisation are shown in Figs. 1–4. The reduction in the size of the fibroids is shown in Table 2.
Table 1. Fibroid characteristics of the women.
*Numbers do not add to 114 since many women had more than one type of fibroid.
Mean age (years)
Total number fibroids
No. of fibroids in each woman
Site of fibroids*
Complex fibroid mass
Size of fibroids (largest diameter, cm)*
Signal intensity, T1 weighted scan
Signal intensity, T2 weighted scans*
High (all heterogeneous)
Table 2. Results of uterine artery embolisation: reduction in size of the fibroids.
Percentage reduction in the size of fibroids Median [Interquartile range]
Total number fibroids
Site of fibroids
Complex fibroid mass
Size of fibroids (cm)
Signal intensity, T1 weighted scans
Signal intensity, T2 weighted scans
High (all heterogeneous)
The median percentage reduction in the volume of the fibroids was 58% (interquartile range 31%–71%. In 10 women the fibroids completely disappeared and a >98% reduction in the volume of the fibroids was demonstrated in a further five women. Hence 15 women (13%) experienced a >98% reduction in the size of their fibroids.
The maximum diameter of the fibroids ranged from 1cm–20cm. Sixty-four women (56%) had fibroids with a diameter >8.5cm. This group included three women in whom the fibroids increased in size after uterine artery embolisation. In the 64 women with larger fibroids the median percentage reduction in the volume of the fibroids was 50% (interquartile range 27%–65%).
Of the three women whose fibroids increased in size one had a diagnostic laparoscopy, one a myomectomy and one a hysterectomy. The myomectomy was carried out at six weeks because of increasing pain and bilateral hydronephrosis. The hysterectomy was at the request of the woman, as her symptoms of compression had not sufficiently improved. The third woman had a diagnostic laparoscopy only.
All the women in the study had T2 weighted and seventy-nine (69%) had T1 weighted sequences on magnetic resonance imaging before and after uterine artery embolisation. The fibroids of seventy-seven (97%) of the women who had T1 weighted scans showed signal characteristics identical to uterine and skeletal muscle making it difficult to assess their origin and size. No additional information was obtained from the T1 weighted images compared with the T2 weighted scans and therefore, as the study continued, T1 weighted sequences were not performed. Two of the 79 women (3%) showed high signal intensity on the T1 weighted scans before embolisation; the reduction in the volume of the fibroids was 66 and 23%.
The fibroids of sixty-eight women (60%) before uterine artery embolisation demonstrated an increased and heterogeneous signal on the T2 weighted scans. Fibroids with signal characteristics higher or brighter than those of skeletal muscle were described as increased and those lower than skeletal muscle were described as low signal fibroids. Forty-six women (40%) had low signal fibroids. Fourteen of these (30%) demonstrated a heterogeneous or non-uniform signal and thirty-two (70%) a homogeneous or uniform signal.
The results of the outcome questionnaire are shown in Table 3. Follow up with the questionnaires ranged from six weeks to 24 months, median 12 months. One hundred and five women (92%) had a minimum follow up of six months.
Table 3. Results of uterine artery embolisation: experiences of the woman.
Overall, n= 114
Women with smaller fibroids (maximum diameter <8.5cm)
Women with larger fibroids (maximum diameter ≥8.5cm)
Twelve women (11%) had a history of myomectomy before uterine artery embolisation and the average reduction in the volume of their fibroids was 50%. Four women (3.5%) became pregnant having tried to conceive before embolisation and the average reduction in the volume of their fibroids was calculated to be 72%.
Three women (3%) developed heavier periods following uterine artery embolisation. This improved in one woman following insertion of a coil. Six women (5%) spontaneously discharged their fibroids transvaginally. Two of these required further hysteroscopy to remove the fibroids completely. The passage of the fibroid material was described as uncomfortable, but the women's symptoms resolved in all these cases. There were no major complications.
The average reduction in the volume of the fibroids was 58%, which agrees with other studies7–11. Several authors have identified factors that predict the outcome of uterine artery embolisation12–14. Jha et al.7 found that the greatest reduction in volume was associated with submucous fibroids.
The diameter of the largest fibroid greater than 8.5cm has been found to predict failure of uterine artery embolisation according to McLucas et al.14 This was not the case in our study. Fifty-six percent of the women had fibroids with a maximum diameter greater than 8.5cm. Although in three women enlargement of the fibroids did occur, the overall reduction in the volume of the fibroids was 50%. Sixty-four percent of these women stated that their symptoms had improved, and they had entirely resolved in 25%; hence 89% women with large fibroids were satisfied with their outcome.
The signal characteristics of tissue on magnetic resonance imaging are due to the amount and distribution of water (i.e. the hydrogen proton). With leiomyomas there are considerable differences in histopathological constitution which result in variable signal on T1 and T2 weighted images. Fibroids commonly undergo degeneration such as hyaline, cystic, myxoid and red degeneration, with hyalinisation in >60% of fibroids. Ooedema that is not due to degeneration is a common finding occurring in approximately 50% of cases. Other findings are haemorrhage, necrosis and calcification. In general the more cellular or hyalinised a fibroid, the lower the intensity of the signal; and the more cystic or ooedematous, the higher is the intensity of the signal on T2 weighted images due to the increased water content15–17. Lesions which are high signal intensity on T1 weighted sequences contain either blood or fat and thus may be due to haemorrhagic necrosis or the rare lipoleiomyoma (0.8% of fibroids)17,18. Burn et al.13 in a series of 18 women found that high signal intensity in fibroids on T1 weighted sequences predicted a poor outcome. Only two women demonstrated high signal on the T1 weighted scans in our study with a mean reduction of the fibroid volume of 45%. Virtually all of the women had a homogeneous signal intensity equal to myometrium and skeletal muscle before embolisation. We therefore found that a high signal intensity on T1 weighted images was uncommon and did not appear to alter the outcome. We do agree with Burn et al.13 that increased signal intensity on T2 weighted sequences was associated with a good response to uterine artery embolisation, the median reduction in the volume of the fibroids being 62%. In 13% of the women in whom there was a greater than 98% reduction in the volume of the fibroids, the intensity of the signal on T2 weighted images was high. In the women with low signal intensity, heterogeneous fibroids had a better outcome than homogeneous fibroids. Our study confirms the findings of Burn et al.13, that low signal intensity was associated with less shrinkage than high signal intensity on T2 weighted scans, but the outcome as far as the women were concerned was good.
This is the largest study of uterine artery embolisation that describes the appearance on magnetic resonance imaging before the embolisation and associates these appearances with the reduction in the volume of the fibroids and the outcome as far as the women were concerned. After their treatment nine-tenths of the women either had no symptoms or found their symptoms were improved. We have shown that uterine artery embolisation is a successful treatment of fibroids, regardless of their size, site or signal characteristics.