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CLINICAL STUDY
Prostatic Artery Embolization for Benign
Prostatic Hyperplasia: Prospective
Randomized Trial of 100–300 μm versus
300–500 μm versus 100- to 300-μm
D300- to 500-μm Embospheres
Daniel Torres, MD, Nuno V. Costa, MD, Jo~
ao Pisco, MD, PhD,
Luis C. Pinheiro, MD, PhD, Antonio G. Oliveira, MD, PhD, and
Tiago Bilhim, MD, PhD, EBIR, FSIR, FCIRSE
ABSTRACT
Purpose: This study compared the safety and efficacy of prostatic arterial embolization (PAE) with that of trisacryl gelatin micro-
spheres of different sizes for treatment of benign prostatic hyperplasia (BPH).
Materials and Methods: This study consisted of a single-center, randomized controlled clinical trial in 138 patients who underwent
PAE for BPH between July 2015 and December 2016. Patients were randomized to PAE using microspheres of different sizes: group A
patients were treated with microspheres 100–300 μm, group B with 300–500 μm, and group C with 100–300 μm followed by 300–500
μm. All patients were evaluated before and at 1, 3, 6, 12, and 18 months after PAE. Baseline data were comparable across the 3 groups,
using the following mean International Prostate Symptom Score/quality of life (IPSS/QoL); prostate volume (PV) scores, respectively:
23.0/4.14; 87.9 cm
3
(group A); 23.0/4.09; 89.0 cm
3
(group B); and 24.2/4.29; 81.0 cm
3
(group C) (P>0.05).
Results: Mean IPSS/QoL scores; PV after PAE were: 9.98/2.49; 65.1 cm
3
(group A); 8.24/2.26; 63.1 cm
3
(group B); and 10.1/2.69;
53.1 cm
3
(group C) (P¼0.23; P¼0.39; P¼0.24). There were 26 clinical failures. The cumulative probabilities of clinical success at
18 months were 76.7% in group A, 82.6% in group B, and 83.3% in group C (P¼0.68). Nontarget embolization was prevented in 6
patients by coil embolization. All adverse events were mild and self-limited with rates of 86.0% in group A (37 of 43); 41.3% in group B
(19 of 46); and 58.3% in group C (28 of 48) (P<0.001). Dysuria was the most frequent adverse event (28 of 137 [20.4%]).
Conclusions: PAE outcomes were not significantly different among microspheres of different sizes. The use of 100- to 300-μm
microspheres was associated with an increased risk of minor adverse events.
ABBREVIATIONS
BPH ¼benign prostatic hyperplasia, IIEF ¼International Index Erectile Function, IPSS ¼International Prostate Symptom Score,
PAE ¼prostatic artery embolization, PSA ¼prostate-specific antigen, PV ¼prostate volume, PVR ¼post-void residual volume,
Qmax ¼uroflowmetry peak urinary flowrate, QoL ¼quality of life
From the Department of Interventional Radiology (D.T., N.V.C., J.P., T.B.),
Hospital Saint Louis, Rua Luz Soriano No. 182, 1200-249, Lisbon, Portugal;
Urology Department (L.C.P.), Hospital S~
ao Jos
e, Centro Hospitalar Uni-
versit
ario de Lisboa Central (CHULC), Lisbon, Portugal; Departments of Radi-
ology (D.T., N.V.C, T.B.) NOVA Medical School, Faculdade de Ci^
encias
M
edicas, Universidade Nova de Lisboa, Lisbon, Portugal; Interventional Radi-
ology Unit (N.V.C.), Curry Cabral Hospital, Centro Hospitalar Universit
ario de
Lisboa Central (CHULC), Lisbon, P ortugal; and Departa mento d e Farm
acia
(A.G.O.), Universidade Federal do Rio Grande do Norte, Natal, Brazil.
Received September 10, 2018; final revision received February 8, 2019;
accepted February 11, 2019. Address correspondence to T.B.; E-mail:
tiagobilhim@hotmail.com
T.B. is a paid consultant for Terumo (Tokyo, Japan) and Merit Medical (South
Jordan, Utah), an advisory board member for Merit Medical, a paid speaker for
Philips (Eindhoven, The Netherlands), and a shareholder in Embolx (Sunnyvale,
California). None of the other authors have identified a conflict of interest.
© SIR, 2019
J Vasc Interv Radiol 2019; 30:638–644
https://doi.org/10.1016/j.jvir.2019.02.014
Several embolic agents have been used for prostatic artery
embolization (PAE) such as nonspherical polyvinyl alcohol
(PVA) particles (Cook Medical Inc., Bloomington, Indiana);
spherical PVA (Bead Block, Biocompatibles UK Ltd.,
Farnham, United Kingdom); trisacryl gelatin microspheres
(Embospheres, Merit Medical Systems Inc., South Jordan,
Utah), and Polyzene-coated hydrogel microspheres (Embo-
zene, CeloNova BioSciences Inc., San Antonio, Texas)
(1–10). Particle sizes used for PAE range between 50 and
300 μm for nonspherical PVA particles and between 100 and
500 μm for spherical embolic agents. The best size with
which to obtain optimal clinical success is not known. PAE
with 100-μm PVA particles leads to a greater decrease in
prostate-specific antigen (PSA) post-void residual volume
(PVR) and a greater increase in uroflowmetry peak urinary
flow (Qmax). However, a greater decrease in International
Prostate Symptom Score (IPSS) and in quality of life (QoL)
was observed with 200-μm PVA particles (7). These find-
ings raised the potential benefit of starting PAE with smaller
embolic agents and finishing with larger ones. Another
study (8) compared 100- to 300-μm with 300- to 500-μm
microspheres for PAE and concluded that clinical outcomes
were similar but that the smaller microspheres led to a
higher incidence of adverse events. The aim of the present
randomized clinical trial was to evaluate and compare the
safety and efficacy of PAE among different sizes of
microspheres.
MATERIALS AND METHODS
Study Population
This single center, open-label, randomized controlled clin-
ical trial in patients with moderate to severe lower urinary
tract symptoms due to benign prostatic hyperplasia (BPH)
receiving PAE with microspheres was approved by the
Institutional Review Board, and all patients signed an
informed consent form. Patients were blinded to the embolic
sizes used, whereas operators were not. The inclusion
criteria were male patients older than 45 years of age with
the diagnosis of BPH with moderate to severe lower urinary
tract symptoms (IPSS 18, and QoL response to IPSS
question 3), Qmax lower than 12 mL/sec, and with sexual
dysfunction or accepting the risk of developing sexual
dysfunction after treatment (11,12). All patients were
informed about the embolization and other therapeutic op-
tions for their clinical situation including transurethral
resection of the prostate, open surgery, and Holmium laser
enucleation of prostate (13). Exclusion criteria were malig-
nancy, secondary renal insufficiency (due to prostatic
enlargement), large bladder diverticula or stones, urethra
stenosis, neurogenic bladder, detrusor failure, and active
urinary tract infection (14).
Patients who were eligible for the trial according to the
criteria underwent pelvic computed tomography (CT)
angiography to assess the degree of vascular calcification as
well as prostatic arterial anatomy. With CT angiography, the
degree of calcium and the prostatic artery origin were
assessed (15). On the basis of CT angiography, the patients
were informed of the difficulties of the procedure and the
probability of technical success rate. Advanced atheroscle-
rosis and tortuosity of iliac arteries were additional exclu-
sion criteria. The technical details of the CT angiography
using sublingual nitroglycerin to identify the prostatic artery
anatomy have been previously described (15). Prostatic bi-
opsies were performed in all patients with suspected pros-
tatic malignancy based on a PSA level greater than 4 ng/mL,
a suspicious focal lesion detected with multiparametric
magnetic resonance imaging, transrectal ultrasonography, or
digital rectal examination. Eligible patients were random-
ized to embolization with trisacryl gelatin microspheres
(Embospheres, Merit Medical Systems Inc.) 100–300 μm
(group A), 300–500 μm (group B), or 100–300 μm followed
by 300–500μm (group C). Patients were allocated by simple
randomization to one of the 3 study groups. Randomization
was performed at the beginning of the study, and patient
allocations were decided on the day of the procedure, prior
to the embolization procedure.
Embolization Technique
Before, during, and after the procedure, the patients had the
same medications previously described (12,16). Patients
were admitted to the hospital 2 hours before the interven-
tion. The embolization was planned in advance, on the basis
of CT angiography, particularly the volume rendering CT
angiography reformats and the maximum intensity pro-
jections (15). These images were available in the angiog-
raphy suite during the procedure (14,15). Once the patients
were on the angiography table, they were allocated to one of
the study groups. Embolization was performed with the
patient under local anesthesia by the unilateral femoral
approach whenever feasible, mostly using the right common
femoral artery, by 3 interventional radiologists with 3–10
years of experience with PAE. A 5-F Roberts uterine cath-
eter (Cook Medical) was introduced into the right femoral
artery in order to catheterize the left internal iliac artery and
its anterior division (14,15). With the catheter at the prox-
imal internal iliac artery, a digital subtraction angiograph
EDITORS’RESEARCH HIGHLIGHTS
This study reinforces the role of prostatic arterial
embolization (PAE) in the treatment of lower urinary
tract symptoms due to benign prostatic hyperplasia.
The authors reported no differences between the
clinical success rates using 100- to 300-μm-sized
particles and those using 300- to 500-μm particles at
18 months, although the incidence of minor self-
limiting complications such as dysuria was greater
with smaller particles.
Greater use of prophylactic coil embolization (4% in
this study) of rectal and accessory pudendal and
vesical arteries may allow a more aggressive particle
embolization with a lower clinical failure rate.
Volume 30 ▪Number 5 ▪May ▪2019 639
(DSA) was obtained in the ipsilateral anterior oblique view
(35) and 10caudocranial angulation, using 6 mL of
iodinated contrast medium (Iopamiro 300, Iomeron, Braco,
Italy) at 3 mL/sec, to visualize the prostatic arteries. After
the left prostatic arteries were identified, a road map was
obtained using the catheter at the origin of the artery in
which those arteries originated. Afterward, the prostatic
vessels were selectively catheterized using a 2.4-F Maestro
microcatheter (Merit Medical Systems Inc.). A DSA in
posteroanterior view was performed with the catheter in the
prostatic artery (5 mL; 2 mL/sec) in order to visualize the
prostate vascularization and vessels leading to potential
nontarget embolization (14). If anastomoses to penis,
rectum, or bladder were identified, with potential for
nontarget embolization, coil embolization was performed
(17) (Fig 1). Before embolization was started, 100–200 μg
of nitroglycerin (Hospira UK Limited, Hurley,
Maidenhead, United Kingdom) was injected through the
microcatheter. The particles were slowly injected through
a 3-cm
3
syringe. In group C, the particles were delivered
sequentially (100–300 μm followed by 300–500 μm). The
endpoint chosen for embolization was “near stasis”in the
prostatic vessels with interruption of the arterial flow or
reflux toward the origin of the prostatic artery or internal
pudendal artery (15,17). A similar procedure was performed
for the contralateral side (18).
Outcome Measurements
Technical success was defined as selective prostatic arterial
catheterization of 1 or both pelvic sides (12). The procedures
were performed on an outpatient basis, and all patients were
discharged 3 to 6 hours after PAE. Pain assessment was
evaluated after PAE and for a period of 3–6 hours after PAE at
discharge using a visual analog scale. Patients were asked to
rate their pain severity from 0 (no sensation of pain) to 10 (the
worst pain). The analysis of pain questionnaires was blinded.
The IPSS/QoL scores were assessed at baseline and at 1, 3, 6,
12, and 18 months after the procedure. PV, Qmax, PVR, the
5-question version of the International Index of Erectile
Function 5 (IIEF-5), and the PSA test results were assessed
before PAE and at 1, 6, and 12 months after PAE. The
prostate volume (PV) was assessed with transrectal ultraso-
nography in all patients and was assessed using magnetic
resonance imaging in 17 patients (12,19,20). The primary
efficacy variable was clinical success, defined as improve-
ment of symptoms: IPSS reduction of at least 25% from
baseline score and 15 points and reduction of QoL of by at
Figure 1. Coil embolization of an accessory pudendal artery during PAE. (a) DSA of left prostatic artery (large arrow) giving rise to an
accessory pudendal artery (arrowhead) anastomosing with the penile artery (arrow) with retrograde opacification of the internal pu-
dendal artery. (b) Selective DSA of the anastomosis to the penile artery. (c) Selective angiography of anastomosis to the penile artery
with retrograde opacification of the internal pudendal artery (arrow). (d) Coils placed in the anastomosis to the penile artery (arrows).
640 ▪Prostatic Artery Embolization for BPH Torres et al ▪JVIR
least 1 point from baseline score or 3 points after PAE (12).
PAE in patients without clinical success was considered a
clinical failure. PAE was considered an initial failure if these
patients did not improve within 1 month after undergoing the
procedure. Short-term PAE failures occurred between 3 and
12 months, and medium-term PAE failures occurred after 1
year. Adverse events were classified according to Society of
Interventional Radiology criteria (11,21).
Statistical Analysis
Descriptive statistics are presented as means ±SD or ab-
solute and relative frequencies. Rates of clinical improve-
ment over time were analyzed using the Kaplan-Meier
method to account for incomplete follow-up times, and
differences between groups in the cumulative probability of
clinical success were tested with the log-rank test. Differ-
ences among groups over time in the response variables
(IPSS, QoL, Qmax, PVR, PSA, PV, and IIEF-5) were
analyzed using multilevel mixed effects linear regression,
with prostate volume, Qmax, and PSA logarithm values
transformed to obtain a normal distribution. Pvalues were
adjusted for multiple comparisons using the Holm-
Bonferroni procedure. Statistical differences were assumed
with a Pvalue <0.05. Stata 13 software (Stata Corp., Col-
lege Station, Texas) was used for all analyses.
RESULTS
Between July 2015 and December 2016, 144 patients with
moderate to severe lower urinary tract symptoms due to
BPH were included in this clinical trial. There were 6
screening failures not meeting the inclusion/exclusion
criteria, thus, 138 patients were allocated by simple
randomization to group A (44 patients), B (46 patients), or
C (48 patients). One patient from group A died of
myocardial infarction before any efficacy data could be
collected and was excluded from the analysis set. There-
fore, the study population consisted of 137 patients divided
into 3 groups: 43 patients in group A, 46 patients in group
B,and48patientsingroupC(Fig 2). The mean patient age
was 66.1 ±8.4 years old (range: 47–86 years of age); mean
baseline IPSS was 23.4 ±5.2 (range: 15–35); and the mean
Figure 2. CONSORT diagram showing flow of patients through the study.
Volume 30 ▪Number 5 ▪May ▪2019 641
baseline PV was 85.9 ±48.5 cm
3
(range: 21–260 cm
3
). The
3 groups were comparable regarding the baseline values of
the study variables (P>0.05) (Tab l e 1 ).
The PAE procedure was performed with the patient under
local anesthesia, using a unilateral femoral approach in 135
and a bilateral approach in 2 patients. PAE was bilateral in
133 patients and unilateral in 4 patients. Mean procedure
time was 85 minutes (range: 22–165 min). Mean fluoros-
copy time was 24.5 minutes (range: 6.8–85 minutes). The
mean procedure pain score during PAE on a 0–10 visual
analog scale was 1.8 (range: 0–7); 113 patients (81.9%) did
not feel any pain. The mean pain score at discharge was 0.8
(range: 0–5).
There were 26 PAE clinical failures (19.0%). Twenty-two
failures (16.1%) were initial clinical failures: 9 in group A, 7
in group B, and 6 in group C. There were 2 failures at short-
term, 1 at 3 months from group C and 1 at 6 months from
group C. The other failure occurred at mid-term at 1 year
from group B. Cumulative probabilities of clinical success at
18 months were 76.7% (95% confidence interval [CI]: 61.1–
86.8%) for group A, 82.6% (95% CI: 68.2–90.9%)
for group B, and 83.3% (95% CI: 69.4–91.3%) for group C
(Fig 3). The differences are not statistically significant
(P¼0.68). Table 2 shows the value of the study
variables at last observation and the percent change from
baseline. In all groups, there was a statistically significant
decrease over time in IPSS, QoL, and PV and a
statistically significant increase in Qmax. In all patients, a
statistically significant improvement from baseline was
seen as early as 1 month after PAE. There were
statistically significant decreases in PSA test results in
group C and no statistically significant changes in IIEF
and PVR. However, there were no statistically significant
differences among groups in any of the variables.
There were no major complications, and there was no
urinary incontinence or erectile dysfunction after PAE.
Changes in ejaculation were not assessed in this trial. Minor
adverse events were evaluated in all 137 patients who were
included in the final analysis. With the exception of 1 fatal
myocardial infarction, which was unrelated to the proced-
ure, occurring 3 months after PAE, all adverse events were
of mild intensity (Table 3). Adverse events included dysuria
(28), frequency (26), hematuria (9), hematospermia (8),
rectal bleeding (6), inguinal hematoma (6), and glans
penis skin lesion (1). All adverse events were mild and
self-limited: 86% in group A (37 of 43); 41% in group B
(19 of 46), and 58% in group C (28 of 48) (P<0.001).
DISCUSSION
The aim of the present study was to investigate which size
microspheres were associated with better results and fewer
adverse events. Previous studies comparing different sizes
of PVA particles (7) or microspheres (8) failed to prove any
significant differences in outcome measurements after PAE
for BPH. The rates of adverse events were not significantly
different among the different sizes of PVA particles (7). The
results of PAE using 300- to 500-μm microspheres was
compared to PAE using 100- to 300-μm microspheres in 15
patients in each group (8). There were no statistically sig-
nificant differences in IPSS, QoL, PSA, or prostate volume
reduction between the 2 groups. The patients in whom the
smaller particle size was used showed a significant regrowth
in prostate size from 3 to 12 months, and there was an in-
crease in minor adverse events in patients who underwent
PAE with smaller microspheres, although this was not sta-
tistically significant. Both of the studies suggested that PAE
using larger particles may be better. The present study
confirms these findings with a larger cohort, proving that the
use of 100- to 300-μm microspheres does not improve
clinical outcomes and leads to a higher rate of minor adverse
events. Data comparing different PVA particle sizes sug-
gested that the combination of sizes, starting with smaller
(80–180 μm) and finishing with larger (180–300 μm) PVA
Figure 3. Cumulative probability of clinical success by size of
microspheres.
Table 1. Baseline Data
Variable Group
A(n¼43) B (n ¼46) C (n ¼48)
n Mean ±SD n Mean ±SD n Mean ±SD
Age, y 43 67.5 8.88 46 65.9 7.86 48 65.1 8.43
IPSS 43 23.0 5.62 46 23.0 5.15 48 24.2 4.89
QoL 43 4.14 1.23 46 4.09 1.07 48 4.29 1.09
PV, cm
3
43 87.9 49.6 46 89.0 51.8 48 81.0 44.8
PVR, mL 30 120.7 83.5 34 108.2 79.8 32 124.2 121.7
Qmax,
mL/min
42 8.23 2.59 44 7.71 2.92 47 8.10 2.88
IIEF 38 18.8 5.57 36 17.9 6.65 42 16.2 6.91
PSA,
ng/dL
43 3.97 2.90 44 4.25 3.09 47 3.74 3.23
IIEF ¼International Index Erectile Function; IPSS ¼Interna-
tional Prostate Symptom Score; PVR ¼post-void residual;
PSA ¼prostate-specific antigen; PV ¼prostate volume;
Qmax ¼uroflowmetry peak urinary flowrate; QoL ¼quality of
life.
642 ▪Prostatic Artery Embolization for BPH Torres et al ▪JVIR
particles could be beneficial (7). Thus, in the present study, a
third group was included in whom 100- to 300-μm particles
were used first, followed by 300- to 500-μm microspheres.
This combination of different sizes also failed to prove
beneficial and was also associated with a higher rate of
adverse events. The number of minor adverse events was
significantly lower in group B, where 100- to 300-μm mi-
crospheres were not used. The patients from groups A and
C, where 100- to 300-μm microspheres were used, had
higher numbers of minor adverse events. This can be
explained by the small size of the microspheres that could
penetrate more distally, causing more inflammation and
necrosis. The glans penis skin lesion could be explained by
the penetration of microspheres 100–300 μm through a
small collateral from an accessory pudendal artery to the
penile artery, as previously reported (12). Even though cone-
beam CT was not available at the time of the study,
preprocedural CT angiography was used to guide inter-
ventionalists during PAE (15), and anastomoses were eval-
uated with selective prostatic artery DSA before
embolization. The technique used was the same for the 3
groups, precluding any potential for procedural bias.
Other groups have shown encouraging results using 50-
μm followed by 100-μm PVA particles (10). More recently,
Table 2. Percent Change from Baseline in Secondary Clinical Variables
Variable by Group Last Observation % Change from Baseline Pvalue*
Mean ±SD Mean 95% CI
IPSS .23
A 9.98 6.67 57.6 64.8 50.5
B 8.24 6.57 64.3 72.7 55.9
C 10.1 5.90 57.9 64.6 51.3
QoL .39
A 2.49 1.20 39.2 47.3 31.0
B 2.26 0.85 43.9 49.0 38.7
C 2.69 0.95 36.6 42.1 31.1
PV, cm
3
.24
A 65.1 38.3 25.1 31.5 18.8
B 63.1 32.4 24.2 30.0 18.3
C 53.1 35.2 35.2 40.8 29.5
PVR, mL .43
A 75.5 65.4 21.2 48.0 5.62
B 68.2 44.9 41.8 65.7 149.2
C 77.1 60.7 279.2 100.4 658.7
Qmax, mL/min .47
A 11.8 3.28 56.1 35.8 76.3
B 12.9 5.29 70.5 51.7 89.2
C 13.8 4.18 81.9 61.4 102.5
IIEF .72
A 16.7 6.62 4.78 16.5 6.93
B 17.6 7.82 5.58 18.0 6.87
C 16.9 8.33 8.13 11.9 28.2
PSA, ng/dL .35
A 2.58 1.79 26.0 36.0 15.9
B 3.09 3.19 5.41 36.8 26.0
C 2.95 2.51 22.8 33.3 78.9
CI ¼confidence interval; IIEF ¼International Index Erectile Function; IPSS ¼International Prostate Symptom Score; PV ¼prostate
volume; Qmax ¼uroflowmetry peak urinary flowrate; QoL ¼quality of life; RPV ¼post-void residual; PSA ¼prostate-specific antigen.
*Multiplicity-adjusted Pvalues >.99 in the comparison among groups in all variables.
Table 3. Adverse Events after PAE
Adverse events Group A
(n ¼43)
Group B
(n ¼46)
Group C
(n ¼48)
Total
(N ¼137)
Dysuria 12 7 9 28
Frequency 11 6 9 26
Hematuria 4 2 3 9
Hematospermia 4 1 3 8
Rectal bleeding 3 1 2 6
Inguinal hematoma 2 2 2 6
Glans penis
skin lesion
10 0 1
Total 37 (86.0) 19 (41.3) 28 (58.3) 84 (61.3)
PAE ¼prostatic artery embolization.
Volume 30 ▪Number 5 ▪May ▪2019 643
the use of 50-μm plus 100-μm PVA particles has shown
better outcomes than the use of 100-μm PVA particles alone
(22). The use of smaller PVA particle sizes led to greater
prostate ischemia, greater prostate volume reduction, and
greater clinical improvement, without a higher rate of
adverse events (22). Retrospective analysis looking at
spherical embolic agents has also shown that spherical
embolic agents <300 μm performed best (23,24). This po-
tential benefit of using smaller sized embolic agents has to
be counterbalanced by the potentially higher rate of adverse
events and ejaculation disorders that have been overlooked
in most PAE studies (25).
Nearly all PAE clinical failures were initial failures,
occurring at 1 month after PAE in PAE nonresponder pa-
tients (12) from all studied groups. This highlights the fact
that patient-related and not procedure-related factors have a
main role in clinical outcomes. Despite the cumulative
probabilities of clinical success being higher in groups B
and C and lower in group A, these differences were not
statistically significant. The potential benefits of combining
smaller (50-μm) PVA particles with larger (100-μm) PVA
particles proven before (22) was not observed in the present
study, which failed to prove any potential benefit of using
100- to 300-μm microspheres followed by 300- to 500-μm
microspheres. It will be exceedingly difficult to show a
statistically significant superiority of 1 particle size over
another. In the present study in 137 patients, the difference
between the clinical success rate observed with the smaller
microspheres and that with the larger microspheres was
approximately 6%. In order to show a 6% increase in the
clinical success rate with 70% power, a clinical trial such as
this one, with a 12-month patient follow-up, would need to
observe approximately 570 events and an estimated sample
size of nearly 2900 patients. Also, the clinical relevance of
such statistical significance could be disputed.
The present study has limitations. It was conducted at a
single center; it was not double-blind; the dropout rate was
significant; there was no long-term follow-up; and ejacula-
tion was not assessed after PAE. More trials should be
performed to compare different embolic agents and particle
sizes to find out the best embolic agent and size for PAE.
In conclusion, use of 100- to 300-μm microspheres either
alone or before 300- to 500-μm microspheres did not lead to
significant differences in clinical outcome and was associ-
ated with a higher rate of minor adverse events. There was
no evidence to support the use of 100- to 300-μm micro-
spheres for PAE.
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