DOI: 10.1148/rg.255045019
RadioGraphics 2005;25:1159-1172
© RSNA, 2005
Uterine Artery Embolization for Leiomyomas: Pre- and Postprocedural Evaluation with US1
Sangeet Ghai, MD,
Dheeraj K. Rajan, MD, FRCPC, FSIR,
Matthew S. Benjamin, MD,
Murray R. Asch, MD, FRCPC and
Sandeep Ghai, MD
1 From the Divisions of Vascular and Interventional Radiology (S.G., D.K.R., M.S.B., M.R.A.) and Women’s Imaging (S.G.), Department of Medical Imaging, Toronto General Hospital, University Health Network–Mount Sinai Hospital, University of Toronto, 585 University Ave, NCSB 1C-553, Toronto, Ontario, Canada M5G 2N2. Presented as an education exhibit at the 2003 RSNA Annual Meeting. Received February 16, 2004; revision requested June 17 and received January 3, 2005; accepted January 10. All authors have no financial relationships to disclose.
Address correspondence to D.K.R. (e-mail: dheeraj.rajan{at}uhn.on.ca).
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Abstract
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Transabdominal and transvaginal ultrasonography (US) are commonly used to assess the uterus and pelvis prior to and following uterine artery embolization (UAE) for symptomatic leiomyomas (fibroids). Preprocedural US may help identify relative contraindications for UAE, whereas postprocedural US can help determine the quality and quantity of fibroid involution and help identify any complications associated with the procedure. The consulting radiologist should be familiar with certain typical postprocedural US findings, which might otherwise be improperly interpreted, leading to unnecessary intervention. Magnetic resonance (MR) imaging or computed tomography will frequently provide the most accurate information in UAE patients with certain pathologic conditions, and early study results suggest that MR imaging may be helpful in predicting treatment response. Nevertheless, US is a readily available first-line imaging modality and a well-accepted method for both pre- and postprocedural evaluation of patients who undergo UAE. A proper understanding of the US findings in this patient population allows objective determination of treatment response and detection of most of the commonly recognized complications that are associated with UAE.
© RSNA, 2005
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Introduction
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Transcatheter embolization of the uterine arteries for treatment of symptomatic leiomyomas was first reported by Ravina et al in 1995 (1). According to survey data obtained by the Society of Interventional Radiology, over 10,000 procedures had been performed by the year 2000 (2). Multiple large prospective and retrospective studies have demonstrated the efficacy and safety of this procedure in reducing or eliminating bleeding, bulk symptoms, or pain with minimal morbidity and mortality, with short-term and midterm clinical success in approximately 85% of patients (3–8).
Uterine artery embolization (UAE) has become an accepted alternative to surgical and medical treatment for symptomatic fibroids (9,10). As this procedure becomes more common, radiologists are becoming increasingly involved in the clinical and imaging follow-up of affected patients. Pelvic ultrasonography (US) has been commonly used for assessment of the uterus and pelvis prior to and following UAE in most large published series. Prior to embolization, US can help identify relative contraindications for embolization such as endometriosis, adenomyosis, pelvic malignancy, pregnancy, and pedunculated fibroids. Following embolization, US is used to monitor the regression or involution of fibroids as well as to identify any complications from the procedure. Complications following UAE that can be visualized with US include fibroid expulsion, sloughing of submucosal fibroids, endometritis, and uterine abscess.
In situations in which US cannot provide an accurate assessment, magnetic resonance (MR) imaging may be performed for further evaluation, particularly in preembolization evaluation. Ascher et al (11) have reported that MR imaging has a higher sensitivity than transvaginal US in diagnosing adenomyosis. Another study found that transvaginal US is as effective as MR imaging in the detection of leiomyomas, but that MR imaging outperforms transvaginal US in the preembolization evaluation of the location, number, and size of leiomyomas (12,13). Furthermore, MR imaging may be useful for predicting the outcome of UAE (14). Leiomyomas with hemorrhagic degeneration and, thus, loss of vascular supply have been shown to have a poor response to UAE (15,16). Persistent perfusion of the fibroid following UAE detected with contrast material–enhanced MR imaging is thought to be predictive of treatment failure and may result in symptom recurrence (17,18). Thus, MR imaging has advantages over US in (a) the differentiation of leiomyoma from adenomyosis, (b) the localization of leiomyomas, (c) the potential prediction of outcome, and (d) monitoring for posttreatment changes and recurrences.
Although MR imaging has potential advantages compared with US, the easy availability of US, its relatively low cost, and its repeatability make it valuable in the evaluation of this group of patients, particularly when MR imaging resources are limited (19). The use of imaging modalities other than US and methods of clinical practice are not the focus of this article. Instead, we discuss and illustrate common pre- and postprocedural US findings in patients who undergo UAE as well as potential complications associated with the procedure.
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Preembolization Evaluation
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Fibroids appear sonographically as well-defined masses within the uterus. They are typically poorly reflective with relatively poor through transmission of sound. Dystrophic calcification may develop in a fibroid as a result of internal degeneration, necrosis, or hemorrhage. Focal or generalized uterine enlargement is common and can be massive. Depending on the location of the fibroids (Fig 1), the uterine outline may be smooth or lobulated and there may be some distortion or displacement of the endometrial echo complex. Subserosal fibroids may cause a lobulated uterine outline, whereas submucosal fibroids cause disruption or distortion of the endometrial lining of the uterus with variable projection into the endometrial cavity (20,21). Pelvic US can help differentiate between submucosal, intramural, subserosal, and pedunculated fibroids (Fig 2). Apart from helping confirm the presence of fibroids, US can be used to evaluate the adnexa and endometrium and to document other disease, if present, to explain a patient’s presenting symptoms.
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Figure 2a. (a, b) Submucosal fibroid. Transverse transvaginal US image (a) and sonohysterogram (b) depict a large submucosal fibroid (F). (c) Subserosal pedunculated fibroids. Axial transabdominal US image shows subserosal pedunculated fibroids (F). UT = uterus.
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Figure 2b. (a, b) Submucosal fibroid. Transverse transvaginal US image (a) and sonohysterogram (b) depict a large submucosal fibroid (F). (c) Subserosal pedunculated fibroids. Axial transabdominal US image shows subserosal pedunculated fibroids (F). UT = uterus.
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Figure 2c. (a, b) Submucosal fibroid. Transverse transvaginal US image (a) and sonohysterogram (b) depict a large submucosal fibroid (F). (c) Subserosal pedunculated fibroids. Axial transabdominal US image shows subserosal pedunculated fibroids (F). UT = uterus.
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Gray-scale US allows an accurate baseline assessment of the number, volume, and location of fibroids (22). Sonohysterography is an important adjunct to transvaginal US in differentiating submucosal fibroids from endometrial polyps (Fig 2b) and in clearly demonstrating the relationship between the endometrium and submucosal leiomyoma (20,21). It is important to correlate the location of the fibroid with the patient’s presenting symptoms. Submucosal leiomyoma is usually responsible for abnormal uterine bleeding, although intramural leiomyoma can encroach on the endometrial cavity and produce menorrhagia. In contrast, it is usually a large intramural or subserosal leiomyoma that results in mass effect on adjacent organs and the corresponding symptoms of urinary frequency or urgency or constipation (23). For this reason, it is imperative to obtain detailed preembolization US images to help determine the volume and location of the fibroids. If prior US examinations are considered to be insufficient, repeat US or MR imaging is performed. It is also important to assess the degree of calcification of fibroids on the preembolization image; marked calcification may indicate the presence of involuted fibroids, which, depending on the degree of degeneration, are unlikely to respond to UAE.
Uterine and fibroid volumes are determined with the formula A x B x C x 0.523, where A, B, and C are the dimensions in the three orientations assuming the fibroid has an ellipsoid shape (7). If multiple fibroids are present, the volumes of the codominant fibroids are measured and then monitored over time, along with the uterine volume (19,24). Doppler US of fibroids is not routinely performed. Pedunculated fibroids (Fig 2c) with an attachment point measuring less than 50% of the diameter of the fibroid following UAE may undergo infarction of the stalk with risk for detachment from the uterus, possibly causing aseptic peritonitis (25). It has also been reported that pedunculated subserosal fibroids may respond less well to UAE due to an alternate blood supply from collateral vessels of the ovarian artery or from neighboring structures to which they adhere (26).
Adenomyosis is a pathologic condition in which there is functional endometrial tissue within the myometrium. MR imaging demonstrates diffuse or focal widening of the junctional zone (Fig 3), with a width of greater than 12 mm considered to be strongly indicative of adenomyosis (27). Alternatively, T1- or T2-weighted MR imaging may also show bright foci in areas of abnormal low signal intensity within the myometrium in 50% of patients (Fig 4b, 4c). Although US in not as sensitive and specific as MR imaging, it can help differentiate adenomyosis from fibroids (11,28). The US appearance of adenomyosis includes myometrial cysts, ill-defined areas of myometrial echotexture, heterogeneous and distorted myometrial echotexture, and a globular or enlarged uterus with asymmetry (Fig 4a) (27,29). In the past, adenomyosis was considered to be a cause of failed UAE despite initial symptomatic relief. However, the recent literature suggests that patients with a diagnosis of adenomyosis may benefit from embolization (30,31). At our institution, if adenomyosis is coincident with fibroids, we proceed with UAE.
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Figure 3a. Adenomyosis in a 34-year-old woman with infertility. Sagittal (a) and coronal (b) T2-weighted MR images of the uterus show indistinct zonal anatomy with widening of the junctional zone (arrows).
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Figure 3b. Adenomyosis in a 34-year-old woman with infertility. Sagittal (a) and coronal (b) T2-weighted MR images of the uterus show indistinct zonal anatomy with widening of the junctional zone (arrows).
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Figure 4a. Adenomyosis in a 47-year-old woman with menorrhagia and pelvic pain. (a) Sagittal transvaginal US image demonstrates an enlarged, globular, diffusely heterogeneous uterus (cursors), a finding that is consistent with adenomyosis. (b, c) Axial T1-weighted (b) and T2-weighted (c) MR images show multiple punctate foci of high signal intensity within the myometrium (arrow), findings that are also consistent with adenomyosis.
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Figure 4b. Adenomyosis in a 47-year-old woman with menorrhagia and pelvic pain. (a) Sagittal transvaginal US image demonstrates an enlarged, globular, diffusely heterogeneous uterus (cursors), a finding that is consistent with adenomyosis. (b, c) Axial T1-weighted (b) and T2-weighted (c) MR images show multiple punctate foci of high signal intensity within the myometrium (arrow), findings that are also consistent with adenomyosis.
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Figure 4c. Adenomyosis in a 47-year-old woman with menorrhagia and pelvic pain. (a) Sagittal transvaginal US image demonstrates an enlarged, globular, diffusely heterogeneous uterus (cursors), a finding that is consistent with adenomyosis. (b, c) Axial T1-weighted (b) and T2-weighted (c) MR images show multiple punctate foci of high signal intensity within the myometrium (arrow), findings that are also consistent with adenomyosis.
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Endometriosis is a common gynecologic disorder that may manifest with symptoms similar to those of symptomatic fibroids. Symptoms include bloating, pelvic pain, dyspareunia, rectal discomfort, and heavy menstrual periods. Noninvasive diagnosis of the most common manifestation of endometriosis—minimal lesion endometriosis, which includes peritoneal implants and pelvic endometriosis—is performed with MR imaging (32). Transvaginal US is the preferred imaging modality for diagnosing ovarian endometriomas, a manifestation of endometriosis, although it has limited usefulness for identifying peritoneal implants (32). The majority of endometriomas appear as focal complex adnexal masses that may be unilocular or multilocular with diffuse low-level internal echoes at US (Fig 5).
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Figure 5a. Endometrioma in a 39-year-old woman with infertility and pelvic pain. (a) Transverse transvaginal US image demonstrates the typical appearance of an endometrioma: a unilocular cyst (C) with low-level echoes, which in this case obscures the right ovary. UT = uterus. (b) Axial T1-weighted MR image of the pelvis shows a high-signal-intensity right adnexal mass (C), a finding that is consistent with an endometrioma. Note also the large simple cyst arising from the left ovary (*).
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Figure 5b. Endometrioma in a 39-year-old woman with infertility and pelvic pain. (a) Transverse transvaginal US image demonstrates the typical appearance of an endometrioma: a unilocular cyst (C) with low-level echoes, which in this case obscures the right ovary. UT = uterus. (b) Axial T1-weighted MR image of the pelvis shows a high-signal-intensity right adnexal mass (C), a finding that is consistent with an endometrioma. Note also the large simple cyst arising from the left ovary (*).
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UAE is also contraindicated when leiomyosarcoma or adnexal malignancy is suspected. A retrospective review by Leibsohn et al (33) of 1432 patients who had undergone hysterectomy for presumed leiomyoma over a 5-year period revealed an overall prevalence of sarcoma of 0.49%. There have been four reported cases of leiomyosarcoma that was discovered after UAE (34–37). If there is continued growth of presumed fibroids after a technically successful embolization procedure, an underlying malignancy should be considered and more definitive therapy recommended.
McLucas et al (38) suggested that uterine artery Doppler flow US may prove useful in pre-screening for UAE. Their study of uterine artery Doppler flow US showed that initial peak systolic velocity correlated positively with the size and shrinkage of myomas and uterine volume. The authors suggested that high peak systolic velocity (>64 cm/sec) was a significant predictor of UAE failure (38).
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Postembolization Evaluation
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Follow-up imaging at our institution is routinely performed at 3, 6, and 12 months after UAE to quantify volume reduction in the uterus and leiomyoma. Volume reduction of the dominant fibroid is greater than that of the uterus, and follow-up US has shown a reduction in uterine size of up to 40%, with the dominant fibroid decreasing in size by up to 70% (5–7,9,39,40). The majority of fibroid shrinkage occurs within a 6-month period following embolization, with further reduction in size occurring between 6 and 12 months (Fig 6) (6). Fibroids have a varied and complex US appearance before and after UAE, a phenomenon that is thought to be secondary to the diverse histologic composition of leiomyomas (40). Weintraub et al (40) described a decrease in the echogenicity of fibroids after embolization (Fig 7, 8). In our experience, however, the majority of fibroids have shown a heterogeneous increase in echogenicity following UAE (Figs 6 , 9).
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Figure 6a. Fibroid size reduction following UAE in a 41-year-old woman. (a) Sagittal transabdominal US image obtained prior to UAE shows an 11-cm posterior intramural uterine fibroid (cursors). (b) On a follow-up sagittal transabdominal US image obtained 3 months after UAE, the fibroid measures 9 cm (cursors). (c) On a follow-up axial transabdominal US image obtained 7 months after UAE, the fibroid measures 4 cm (cursors).
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Figure 6b. Fibroid size reduction following UAE in a 41-year-old woman. (a) Sagittal transabdominal US image obtained prior to UAE shows an 11-cm posterior intramural uterine fibroid (cursors). (b) On a follow-up sagittal transabdominal US image obtained 3 months after UAE, the fibroid measures 9 cm (cursors). (c) On a follow-up axial transabdominal US image obtained 7 months after UAE, the fibroid measures 4 cm (cursors).
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Figure 6c. Fibroid size reduction following UAE in a 41-year-old woman. (a) Sagittal transabdominal US image obtained prior to UAE shows an 11-cm posterior intramural uterine fibroid (cursors). (b) On a follow-up sagittal transabdominal US image obtained 3 months after UAE, the fibroid measures 9 cm (cursors). (c) On a follow-up axial transabdominal US image obtained 7 months after UAE, the fibroid measures 4 cm (cursors).
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Figure 7a. Peripheral fibroid calcification following UAE in a 50-year-old woman. (a, b) Axial transabdominal US images obtained prior to UAE demonstrate multiple intramural (M) and subserosal (S) fibroids in different locations (cursors). (c, d) On US images obtained 3 years after UAE, the fibroids are hypoechoic with decreased volumes (cursors in c). Note also the hyperechoic rim around the involuted fibroids with distal shadowing (arrows), findings that are consistent with calcification and that mimic the appearance of a fetal head.
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Figure 7b. Peripheral fibroid calcification following UAE in a 50-year-old woman. (a, b) Axial transabdominal US images obtained prior to UAE demonstrate multiple intramural (M) and subserosal (S) fibroids in different locations (cursors). (c, d) On US images obtained 3 years after UAE, the fibroids are hypoechoic with decreased volumes (cursors in c). Note also the hyperechoic rim around the involuted fibroids with distal shadowing (arrows), findings that are consistent with calcification and that mimic the appearance of a fetal head.
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Figure 7c. Peripheral fibroid calcification following UAE in a 50-year-old woman. (a, b) Axial transabdominal US images obtained prior to UAE demonstrate multiple intramural (M) and subserosal (S) fibroids in different locations (cursors). (c, d) On US images obtained 3 years after UAE, the fibroids are hypoechoic with decreased volumes (cursors in c). Note also the hyperechoic rim around the involuted fibroids with distal shadowing (arrows), findings that are consistent with calcification and that mimic the appearance of a fetal head.
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Figure 7d. Peripheral fibroid calcification following UAE in a 50-year-old woman. (a, b) Axial transabdominal US images obtained prior to UAE demonstrate multiple intramural (M) and subserosal (S) fibroids in different locations (cursors). (c, d) On US images obtained 3 years after UAE, the fibroids are hypoechoic with decreased volumes (cursors in c). Note also the hyperechoic rim around the involuted fibroids with distal shadowing (arrows), findings that are consistent with calcification and that mimic the appearance of a fetal head.
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Figure 8a. Peripheral fibroid calcification following UAE in a 47-year-old woman. (a) Axial transabdominal US image obtained prior to UAE shows a 3.2-cm subserosal fibroid (cursors). (b) Axial US image obtained 7 months after UAE shows a decrease in the volume of the fibroid (cursors), which is now involuted and measures 1.9 cm, with a hyperechoic calcific rim at the margin (arrow).
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Figure 8b. Peripheral fibroid calcification following UAE in a 47-year-old woman. (a) Axial transabdominal US image obtained prior to UAE shows a 3.2-cm subserosal fibroid (cursors). (b) Axial US image obtained 7 months after UAE shows a decrease in the volume of the fibroid (cursors), which is now involuted and measures 1.9 cm, with a hyperechoic calcific rim at the margin (arrow).
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Figure 9a. Intraparenchymal gas within a fibroid following UAE. (a, b) Axial transabdominal US image obtained prior to UAE (a) reveals a large, 11-cm intramural fibroid (cursors). Follow-up sagittal transvaginal US image obtained 4 months after UAE (b) shows a decrease in the size of the fibroid (cursors), which now measures 7 cm. Note also the multiple focal bright areas (arrows) with reverberation artifacts representing intraparenchymal gas. The patient was asymptomatic. (c) Computed tomographic (CT) scan of the pelvis obtained 2 months after UAE in a different patient demonstrates large cavitating fibroids (F). Note the air within the fibroids (arrows), a finding that is consistent with necrosis.
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Figure 9b. Intraparenchymal gas within a fibroid following UAE. (a, b) Axial transabdominal US image obtained prior to UAE (a) reveals a large, 11-cm intramural fibroid (cursors). Follow-up sagittal transvaginal US image obtained 4 months after UAE (b) shows a decrease in the size of the fibroid (cursors), which now measures 7 cm. Note also the multiple focal bright areas (arrows) with reverberation artifacts representing intraparenchymal gas. The patient was asymptomatic. (c) Computed tomographic (CT) scan of the pelvis obtained 2 months after UAE in a different patient demonstrates large cavitating fibroids (F). Note the air within the fibroids (arrows), a finding that is consistent with necrosis.
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Figure 9c. Intraparenchymal gas within a fibroid following UAE. (a, b) Axial transabdominal US image obtained prior to UAE (a) reveals a large, 11-cm intramural fibroid (cursors). Follow-up sagittal transvaginal US image obtained 4 months after UAE (b) shows a decrease in the size of the fibroid (cursors), which now measures 7 cm. Note also the multiple focal bright areas (arrows) with reverberation artifacts representing intraparenchymal gas. The patient was asymptomatic. (c) Computed tomographic (CT) scan of the pelvis obtained 2 months after UAE in a different patient demonstrates large cavitating fibroids (F). Note the air within the fibroids (arrows), a finding that is consistent with necrosis.
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Air may be seen within the fibroid following UAE. This finding is thought to be the result of gas filling potential spaces left by tissue infarction-desiccation—similar to the gas seen after ethanol-radiofrequency ablation or chemoembolization of a hepatoma (Fig 9) (41,42)—and can be seen as early as 1 month following UAE (43,44). It is very important to be aware of this finding because it rarely represents infection, and improper diagnosis may lead to unnecessary intervention. It is essential to correlate imaging, laboratory, and clinical findings to exclude infection of the fibroids.
The "fetal head sign" has been described at US performed 6 months to 1 year after UAE. A hyperechoic rim representing peripheral calcification around an increasingly hypoechoic fibroid results in such an appearance (Figs 7, 8). The peripheral location of calcification following embolization differs from that of the dystrophic calcification that may be seen centrally with natural fibroid involution and hyaline necrosis. Nicholson et al (45) have suggested that the peripheral calcification is the end result of the aggregation of polyvinyl alcohol particles in peripheral fibroid arteries.
Occasionally, polyvinyl alcohol particles may be seen within the uterine arteries following embolization. The particles are sized to lodge at the arteriolar level, thereby causing distal occlusion, and to prevent passage through the capillary bed of the uterus or fibroids. As flow in a uterine artery becomes stagnant during the procedure, the particles become incorporated within blood clot in the artery. The polyvinyl alcohol particles remain in the clot as it becomes organized and appear as echogenic areas within the uterine artery (Fig 10).
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Figure 10a. Embolic particles and organized clot within the uterine arteries. (a) Follow-up sagittal transabdominal US image obtained 6 months after UAE in a 51-year-old woman shows a stagnant echogenic column within a tortuous uterine artery (arrow). (b) Follow-up sagittal transvaginal US image obtained 4 months after UAE in a 40-year-old woman shows a similar-appearing echogenic column within a uterine artery (arrow).
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Figure 10b. Embolic particles and organized clot within the uterine arteries. (a) Follow-up sagittal transabdominal US image obtained 6 months after UAE in a 51-year-old woman shows a stagnant echogenic column within a tortuous uterine artery (arrow). (b) Follow-up sagittal transvaginal US image obtained 4 months after UAE in a 40-year-old woman shows a similar-appearing echogenic column within a uterine artery (arrow).
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Color Doppler US usually shows a marked decrease in the blood flow to fibroids after embolization. Disappearance of intrafibroid vascularity is common, whereas flow in perifibroid vessels persists (Fig 11) (19). No statistical correlation between the decrease in the size of the fibroid and the color flow US appearance of the fibroid before embolization has been noted (Fig 12) (40).
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Figure 11. Absence of intrafibroid vascularity following UAE in a 35-year-old woman. Transverse transvaginal color Doppler US image obtained 6 months after UAE shows an intramural fibroid (F). Note the absence of intrafibroid vascularity, with persistence of flow within the perifibroid vessels.
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Figure 12. Persistence of intrafibroid and perifibroid vessels following UAE in a 47-year-old woman. Transverse transvaginal duplex color power Doppler US image obtained 2 months after UAE shows persistent perifibroid and intrafibroid vessels. However, the fibroid had decreased in volume compared with its preembolization size.
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Complications
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Major complications following UAE are rare (46) compared with major complications following traditional surgical procedures for treating symptomatic fibroids. There have been three reported deaths within 30 days following UAE: two from uterine infection and overwhelming sepsis and a third from massive pulmonary embolism (47–49). The overall periprocedural complication rate for UAE, including both major and minor complications, is approximately 8%, with an infection-related complication rate of up to 2% (23,37). A majority of these complications are minor and represent allergic reactions (37). In a recent report by Pinto et al (50), the major complication rate following hysterectomy was 20% (four of 20 patients), compared with a 2.5% major complication rate (one of 40 patients) following UAE.
Transcervical expulsion of myomas has been described in several studies and is not uncommon, with a reported rate of up to 3% (37,51,52). Affected patients may present with uterine contractions, abdominal pain, or heavy vaginal bleeding or discharge months after undergoing UAE. They are also prone to develop infection, with passage of sloughed leiomyoma (25). In most cases, the myomas are expelled spontaneously (Fig 13). Occasionally, hysteroscopic resection or dilatation and curettage is required. This complication appears to occur only with fibroids (submucosal and intramural leiomyomas) that are in contact with the endometrial surface (37). Patients with large submucosal fibroids are also thought to be at risk for severe genitourinary infection, possibly due to necrotizing leiomyomas acting as an ideal medium for bacterial development transmitted from the vaginal vault (53).
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Figure 13a. Fibroid expulsion in a 48-year-old woman. (a, b) Transverse (a) and sagittal (b) transvaginal US images obtained prior to UAE show a large intramural fibroid (cursors) with a submucosal component and a normal cervical canal (C). Two months after undergoing UAE, the patient presented with complaints of pain and vaginal bleeding. (c, d) Sagittal transvaginal US images demonstrate the large fibroid (arrows) to be partially expulsed and now present within the endocervical canal. (e) Sagittal transvaginal US image obtained 6 months after UAE demonstrates a normal-appearing uterus with no fibroid in an intramural-submucosal location or within the endocervical canal. The patient provided a history of passing tissue per vaginum shortly after the previous US study.
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Figure 13b. Fibroid expulsion in a 48-year-old woman. (a, b) Transverse (a) and sagittal (b) transvaginal US images obtained prior to UAE show a large intramural fibroid (cursors) with a submucosal component and a normal cervical canal (C). Two months after undergoing UAE, the patient presented with complaints of pain and vaginal bleeding. (c, d) Sagittal transvaginal US images demonstrate the large fibroid (arrows) to be partially expulsed and now present within the endocervical canal. (e) Sagittal transvaginal US image obtained 6 months after UAE demonstrates a normal-appearing uterus with no fibroid in an intramural-submucosal location or within the endocervical canal. The patient provided a history of passing tissue per vaginum shortly after the previous US study.
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Figure 13c. Fibroid expulsion in a 48-year-old woman. (a, b) Transverse (a) and sagittal (b) transvaginal US images obtained prior to UAE show a large intramural fibroid (cursors) with a submucosal component and a normal cervical canal (C). Two months after undergoing UAE, the patient presented with complaints of pain and vaginal bleeding. (c, d) Sagittal transvaginal US images demonstrate the large fibroid (arrows) to be partially expulsed and now present within the endocervical canal. (e) Sagittal transvaginal US image obtained 6 months after UAE demonstrates a normal-appearing uterus with no fibroid in an intramural-submucosal location or within the endocervical canal. The patient provided a history of passing tissue per vaginum shortly after the previous US study.
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Figure 13d. Fibroid expulsion in a 48-year-old woman. (a, b) Transverse (a) and sagittal (b) transvaginal US images obtained prior to UAE show a large intramural fibroid (cursors) with a submucosal component and a normal cervical canal (C). Two months after undergoing UAE, the patient presented with complaints of pain and vaginal bleeding. (c, d) Sagittal transvaginal US images demonstrate the large fibroid (arrows) to be partially expulsed and now present within the endocervical canal. (e) Sagittal transvaginal US image obtained 6 months after UAE demonstrates a normal-appearing uterus with no fibroid in an intramural-submucosal location or within the endocervical canal. The patient provided a history of passing tissue per vaginum shortly after the previous US study.
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Figure 13e. Fibroid expulsion in a 48-year-old woman. (a, b) Transverse (a) and sagittal (b) transvaginal US images obtained prior to UAE show a large intramural fibroid (cursors) with a submucosal component and a normal cervical canal (C). Two months after undergoing UAE, the patient presented with complaints of pain and vaginal bleeding. (c, d) Sagittal transvaginal US images demonstrate the large fibroid (arrows) to be partially expulsed and now present within the endocervical canal. (e) Sagittal transvaginal US image obtained 6 months after UAE demonstrates a normal-appearing uterus with no fibroid in an intramural-submucosal location or within the endocervical canal. The patient provided a history of passing tissue per vaginum shortly after the previous US study.
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Endometritis is uncommon following UAE, with a prevalence of 1%–2% (22,37). At clinical examination, patients present with pelvic pain, watery vaginal discharge, fever, or leukocytosis. Endometritis can occur days to weeks after embolization. In a study by Rajan et al (54), all patients who developed intrauterine infections had submucosal fibroids or fibroids with submucosal extension. Preprocedural administration of antibiotics did not influence the risk of infection. Although the US appearance of the endometrium and uterus may be normal in endometritis, findings may include a thickened, heterogeneous endometrium; intracavitary fluid; and intrauterine air (Fig 14). Correlation with clinical and laboratory findings is recommended to verify the diagnosis.
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Figure 14a. Endometritis in a 35-year-old woman who presented with fever and vaginal discharge 4 weeks after undergoing UAE. Sagittal transabdominal (a) and transvaginal (b) US images show multiple echogenic foci (arrows) with reverberation artifacts, findings that represent gas within a thickened endometrium.
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Figure 14b. Endometritis in a 35-year-old woman who presented with fever and vaginal discharge 4 weeks after undergoing UAE. Sagittal transabdominal (a) and transvaginal (b) US images show multiple echogenic foci (arrows) with reverberation artifacts, findings that represent gas within a thickened endometrium.
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Diffuse uterine necrosis is a rare potential complication of UAE, with a reported prevalence of less than 1%. This complication is especially rare if the normal pelvic collateral circulation is intact (55). Intrauterine abscess formation with sepsis has been reported in conjunction with uterine necrosis (47,48,55). Patients commonly present with abdominal or pelvic pain, vaginal discharge, fever, or leukocytosis. These patients often require hysterectomy as a result of the complication (Fig 15) (6,56,57). Two deaths due to uterine infection following UAE have been reported, with both deaths occurring within the first 30 days following the procedure (47,48). Poor collateral circulation has been postulated as the cause of uterine abscess-necrosis following UAE.
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Figure 15a. Uterine abscess in a 51-year-old woman with septicemia. The patient had undergone UAE 3 months earlier. (a) Axial transabdominal US image of the uterus shows a large uterine abscess (cursors) with diffuse hyperechoic foci (arrow), findings that are consistent with gas. (b, c) CT scans obtained at different levels through the uterus help confirm a large uterine abscess with an air-fluid level (arrow in b). The patient subsequently underwent hysterectomy.
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Figure 15b. Uterine abscess in a 51-year-old woman with septicemia. The patient had undergone UAE 3 months earlier. (a) Axial transabdominal US image of the uterus shows a large uterine abscess (cursors) with diffuse hyperechoic foci (arrow), findings that are consistent with gas. (b, c) CT scans obtained at different levels through the uterus help confirm a large uterine abscess with an air-fluid level (arrow in b). The patient subsequently underwent hysterectomy.
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Figure 15c. Uterine abscess in a 51-year-old woman with septicemia. The patient had undergone UAE 3 months earlier. (a) Axial transabdominal US image of the uterus shows a large uterine abscess (cursors) with diffuse hyperechoic foci (arrow), findings that are consistent with gas. (b, c) CT scans obtained at different levels through the uterus help confirm a large uterine abscess with an air-fluid level (arrow in b). The patient subsequently underwent hysterectomy.
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Deep venous thrombosis has a reported prevalence of less than 1% in this patient population but may occur more frequently due to large draining pelvic veins from the uterus (Fig 16) (23,37). There have been isolated reports of pulmonary embolism following UAE, with a single reported death resulting from pulmonary embolism (49).
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Figure 16a. Deep venous thrombosis in a 52-year-old woman with a history of acute unilateral limb swelling since undergoing UAE 4 days earlier. (a) Longitudinal color Doppler US image shows an occlusive homogeneous thrombus within a noncompressible right common femoral vein (V). (b) Longitudinal gray-scale US image shows the thrombus in the common femoral vein (CFV) and extending into the greater saphenous vein (GSV).
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Figure 16b. Deep venous thrombosis in a 52-year-old woman with a history of acute unilateral limb swelling since undergoing UAE 4 days earlier. (a) Longitudinal color Doppler US image shows an occlusive homogeneous thrombus within a noncompressible right common femoral vein (V). (b) Longitudinal gray-scale US image shows the thrombus in the common femoral vein (CFV) and extending into the greater saphenous vein (GSV).
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Puncture site hematomas, pseudoaneurysm formation (Fig 17), arterial dissection, and guide wire perforation of the arteries selected during UAE are complications that can be associated with any angiographic procedure and are not specific to UAE.
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Figure 17. Pseudoaneurysm at the arterial puncture site in a 52-year-old woman who had undergone UAE. Duplex color Doppler US image demonstrates a heterogeneous, echogenic swirling mass adjacent to the common femoral artery (CFA) at the puncture site with arterial flow. A narrow "neck" (arrow) is identified in the pseudoaneurysm.
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UAE has been associated with loss of ovarian function in up to 14% of patients (58,59) and appears to be age related, with a higher risk in patients over 45 years of age (7,59). Embolic particles injected into a uterine artery can migrate through anastomotic channels into the ovarian arterial vasculature and potentially compromise ovarian blood flow (60). Oocytes are particularly vulnerable to hypoxia. The clinical observation that the risk of immediate ovarian failure is greater in women over 45 years of age may be due to fewer oocytes remaining at this age (23). This observation also suggests that undetected oocyte loss may occur in a significant percentage of women undergoing UAE (58).
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Conclusions
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In certain pathologic conditions, MR imaging or CT will frequently provide the most accurate information, with early studies suggesting that MR imaging may be helpful in predicting clinical response. Nevertheless, US is a readily available first-line imaging modality. US is a well-accepted method for preprocedural and follow-up evaluation of patients who undergo UAE. A proper understanding of the US findings in this patient population allows an objective determination of response to embolization. In addition, US is effective in detecting most of the commonly recognized complications that are associated with this procedure.
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Footnotes
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See the commentary by Spies following this article.
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References
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Abstract
Introduction
