DOI:10.2214/AJR.05.1638
AJR 2006; 187:959-964
© American Roentgen Ray Society
Sonography, CT, and MRI Appearance of the Essure Microinsert Permanent Birth Control Device
Michael H. Wittmer1,
Douglas L. Brown1,
Robert P. Hartman1,
Abimbola O. Famuyide2,
Akira Kawashima1 and
Bernard F. King1
1 Department of Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN
55905.
2 Department of Obstetrics and Gynecology, Mayo Clinic, Rochester, MN.
Received September 14, 2005;
accepted after revision February 14, 2006.
Address correspondence to M. H. Wittmer
(wittmer.michael{at}mayo.edu).
Abstract
OBJECTIVE. The purpose of this article is to describe the appearance
and location of the Essure permanent birth control device on sonography, CT,
and MRI.
CONCLUSION. The Essure device has a distinct appearance and typical
location that allow it to be accurately identified on sonography, CT, and MRI
scans.
Keywords: birth control • CT • Essure microinsert • genitourinary tract imaging • implantable devices • MRI • pelvic imaging • sonography
Introduction
The Essure microinsert (Conceptus, Inc.) is the first hysteroscopically
placed permanent female birth control device to be approved by the U.S. Food
and Drug Administration (FDA). Before it received FDA approval in November
2002, a few other mechanical devices had been used experimentally. None gained
widespread use, however, largely because of their unacceptable expulsion and
failure rates [1]. Silicone was
first placed hysteroscopically in the early 1970s
[2]. Ovabloc, a silicone-based
system, was evaluated in a cohort of 392 patients from The Netherlands
[3]. Instillation of the
silicone failed in 64 patients, spontaneous expulsion of the silicone plugs
occurred in 20 patients, removal of the plugs because of complaints or regrets
about sterilization occurred in 10 patients, and pregnancies occurred in two
patients. Problems with placement, expulsion, or both were also reported with
the nylon-based P-block [4]
and, more recently, with the tubal screw device
[5].
The Essure device in its early form was known as STOP (Selective Tubal
Occlusion Device). The phase 2 trials started in 1998
[6] and the phase 3 trials in
2000 [7] ultimately led to FDA
approval in 2002. To date, at least 45,000 devices have been placed worldwide,
approximately 60% of which have been placed in patients in the United States
(personal communication, Conceptus, Inc., December 2005).
The Essure microinsert is made of an inner flexible stainless steel coil
surrounded by an outer coil made of nickel titanium alloy
(Fig. 1). The ends of the inner
and outer coils are delineated by radiopaque markers. The central inner coil
is surrounded by white polyethylene terephthalate fibers, which generate
benign local tissue ingrowth when in contact with tissue
[7-9].
The inner coil attaches to a guidewire used for placement.
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Fig. 1 —Photograph of Essure microinsert (Conceptus, Inc.). Noted are
two radiopaque markers at ends of inner (central) coil (long arrows),
and two radiopaque markers at ends of outer (spring) coil (short
arrows). Portion of inner coil is surrounded by white polyethylene
terephthalate fibers. Inner coil end of device is placed into fallopian tube,
and outer coil protrudes into uterine cavity.
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The outer spring coil is highly elastic and expands when released from the
guidewire. The diameter of the wound-down device before release is 0.8 mm. The
expanded device measures 4 cm in length over 26 outer coils, with a maximum
expanded diameter of between 1.5 and 2 mm. By use of catheter and
hysteroscopic guidance, the microinsert is placed in the proximal portion of
the fallopian tube. When deployed in the tubal lumen, the outer coil expands
to anchor the device in place. Optimum device positioning is considered to be
achieved when 5-10 mm of the outer coil is within the uterine cavity
[7]. At our institution,
optimal device positioning is achieved during hysteroscopic placement when
three to eight coils of the device are visible at the ostium
(Fig. 2A). Over a 3-month
period, the tubal lumen is occluded by tissue growth, which is stimulated by
the polyethylene terephthalate fibers in the inner coil.
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Fig. 2A —39-year-old woman for whom hysteroscopic still image was
taken after placement of Essure devices (Conceptus, Inc.). Shown are proximal
tip of inner central coil (small arrow) and proximal tip of outer
spring coil (large arrow). Also noted are tubal ostia in each cornu
of uterus (arrowheads). Few loops of expanded outer coil can be seen
in uterine cavity.
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As part of the recent FDA approval of the Essure microinsert,
hysterosalpingography (HSG) is required to be performed on each patient 3
months after device placement. The traditional radiographic HSG
(Fig. 2B) is the only imaging
method currently approved by the FDA to assess tubal patency in patients with
the Essure device. The HSG can document device location and tubal occlusion.
The HSG appearance of the device and method of evaluation are described
elsewhere [10,
11]. The Essure device may be
incidentally identified with other techniques such as sonography, CT, and MRI.
These other imaging techniques may play a future role in evaluating the
position and function of the device; however, HSG is currently the only
approved technique for postplacement device evaluation
[12]. Even though sonography,
CT, and MRI are not routinely used to image the device at this time, as the
procedure becomes more common, radiologists are likely to encounter the device
incidentally when pelvic sonography, CT, or MRI is performed for other reasons
in these patients. Familiarity with the expected appearance and location of
the Essure microinsert on these examinations should facilitate accurate
interpretation. The purpose of this study is to describe the sonography, CT,
and MRI appearance of the Essure microinsert.
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Fig. 2B —39-year-old woman for whom hysteroscopic still image was
taken after placement of Essure devices (Conceptus, Inc.). Hysterosalpingogram
(HSG) of Essure devices (arrows) in satisfactory position. No free
spill of contrast agent is seen, indicating tubal occlusion bilaterally.
Balloon catheter (arrowhead) used for HSG is noted.
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Materials and Methods
We searched the electronic medical records of all women who had undergone
placement of the Essure microinsert at our institution between March 2003
(when device placement was first performed at our institution) and August 2004
to identify those who also had sonography, CT, or MRI performed after device
placement. Inclusion criteria for device placement were women of reproductive
age who sought permanent sterilization. Exclusion criteria for device
placement were current or recent pregnancy (within the previous 6 weeks),
active genital infection, prior tubal disease or tubal surgery, known
congenital uterine malformation, and hypersensitivity to nickel or contrast
dye.
The study was approved by our institutional review board. The HSGs,
sonographic images, CT scans, and MR images were retrospectively reviewed by
two radiologists to record the appearance and location of the devices.
Identification of the Essure devices and descriptions of the devices'
appearances were determined by consensus. In each case, the sonography, CT, or
MRI was performed for reasons unrelated to the Essure microinsert. The HSG was
considered the gold standard for device location, with general device location
considered correct by each technique when the device was seen in the uterine
cornua. We did not perform measurements to determine position, as may be done
on the HSG [10,
11].
Results
Essure devices were placed in 52 patients at our institution between March
2003 and August 2004. Eight of these 52 patients had an acceptable imaging
study performed after device placement. The eight patients ranged in age from
21 to 41 years (mean, 32.6 years). All had had bilateral placement of Essure
devices. Of the eight patients, six CT scans of the pelvis at 5-mm slice
thickness were found for five patients, five pelvic sonography examinations
were found for four patients, and one pelvic MRI examination was found for one
patient. Only one patient had had both CT and sonography examinations after
Essure placement. Indications for CT included abdominal pain (n = 3),
suspected urinary calculi (n = 2), and cirrhosis (n = 1).
Indications for sonography included abdominal pain (n = 2), bleeding
(n = 2), and evaluation of fibroids (n = 1). The MRI
examination was performed to evaluate a perianal fistula. For each patient,
one device was identified in each fallopian tube, regardless of the technique
used.
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Fig. 3A —Sonograms of 37-year-old woman with Essure device implant
(Conceptus, Inc.). Transverse transabdominal sonographic image of pelvis shows
two parallel interrupted echogenic lines, corresponding to outer coil of
Essure device (arrows).
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Fig. 3B —Sonograms of 37-year-old woman with Essure device implant
(Conceptus, Inc.). Transverse endovaginal sonography image of pelvis shows
Essure device as two parallel interrupted echogenic lines, corresponding to
outer coil (arrows) of device in left fallopian tube.
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Fig. 3C —Sonograms of 37-year-old woman with Essure device implant
(Conceptus, Inc.). Within outer coil of device in right fallopian tube, one is
able to identify linear, echogenic line, corresponding with inner coil
(arrows) of Essure device.
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Fig. 4A —29-year-old woman with Essure device implant (Conceptus,
Inc.) seen on CT. Consecutive 5-mm slice thickness CT scans, obtained through
pelvis (progressing superior to inferior from A to D) and
displayed using soft-tissue windows, show linear regions of high attenuation
(short arrows), (A and D) corresponding to Essure
microinserts within uterine cornua, extending into proximal fallopian tubes.
Radiopaque markers at ends of inner and outer coils generate small amount of
radiating rays of artifact (long arrows), (B and
C).
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Fig. 4B —29-year-old woman with Essure device implant (Conceptus,
Inc.) seen on CT. Consecutive 5-mm slice thickness CT scans, obtained through
pelvis (progressing superior to inferior from A to D) and
displayed using soft-tissue windows, show linear regions of high attenuation
(short arrows), (A and D) corresponding to Essure
microinserts within uterine cornua, extending into proximal fallopian tubes.
Radiopaque markers at ends of inner and outer coils generate small amount of
radiating rays of artifact (long arrows), (B and
C).
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Fig. 4C —29-year-old woman with Essure device implant (Conceptus,
Inc.) seen on CT. Consecutive 5-mm slice thickness CT scans, obtained through
pelvis (progressing superior to inferior from A to D) and
displayed using soft-tissue windows, show linear regions of high attenuation
(short arrows), (A and D) corresponding to Essure
microinserts within uterine cornua, extending into proximal fallopian tubes.
Radiopaque markers at ends of inner and outer coils generate small amount of
radiating rays of artifact (long arrows), (B and
C).
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Fig. 4D —29-year-old woman with Essure device implant (Conceptus,
Inc.) seen on CT. Consecutive 5-mm slice thickness CT scans, obtained through
pelvis (progressing superior to inferior from A to D) and
displayed using soft-tissue windows, show linear regions of high attenuation
(short arrows), (A and D) corresponding to Essure
microinserts within uterine cornua, extending into proximal fallopian tubes.
Radiopaque markers at ends of inner and outer coils generate small amount of
radiating rays of artifact (long arrows), (B and
C).
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All sonographic studies included both transabdominal
(Fig. 3A) and endovaginal
(Figs. 3B and
3C) images. Endovaginal images
were generally of superior quality compared with the transabdominal images. In
all cases, the device was seen in the correct location at the cornual region
of the uterus, with the proximal end of the device near the
endometrial-myometrial junction. In all of the sonograms, the device was
curved, and therefore the nonlinear shape of the device made visualization of
the entire device on a single image plane difficult. Although the proximal
(i.e., uterine) end of the device was seen in each case, we could never be
sure that the full distal (i.e., tubal) extent of the device was being seen,
probably because of obscuration by bowel gas. In no cases were the radiopaque
markers at the ends of the coils visible on sonographic images. In all cases,
the Essure device was seen as two parallel interrupted echogenic lines,
corresponding to the wires of the outer coil. A central, linear echogenic
line, felt to correspond with the inner coil, was seen in the endovaginal
images on only one of the five sonograms (Figs.
3B and
3C). In each case, the device
position seen on sonography agreed with that shown on HSG.
On CT, the Essure device was easily identified as a linear region of high
attenuation within the fallopian tubes and uterine cavity (Figs.
4A,
4B,
4C, and
4D) on all six scans. The fine
details of the coils and the radiopaque markers were better visualized when
the CT images were viewed on bone windows, but soft-tissue windows better
showed the device position within the fallopian tubes and uterine cavity. The
curvilinear shape of the device seen sonographically was not as obvious on CT,
most likely because of the single scan plane for CT.
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Fig. 5A —41-year-old woman with Essure device implant (Conceptus,
Inc.) seen on MRI. Axial (A) and coronal (B) gadolinium-enhanced
gradient-echo MR images with fat saturation through pelvis show metallic
artifact related to Essure devices (arrows) in place in bilateral
fallopian tubes. In coronal image (B), entire length of device on left
is shown, and right device is seen in cross section.
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Fig. 5B —41-year-old woman with Essure device implant (Conceptus,
Inc.) seen on MRI. Axial (A) and coronal (B) gadolinium-enhanced
gradient-echo MR images with fat saturation through pelvis show metallic
artifact related to Essure devices (arrows) in place in bilateral
fallopian tubes. In coronal image (B), entire length of device on left
is shown, and right device is seen in cross section.
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In none of the CT studies was the inner coil distinguishable from the outer
spring coil. The radiopaque markers at the ends of the inner and outer coils,
however, were easily visible in all cases, and generated a small amount of
metal artifact on CT. In all cases, the device was seen in the correct
location at the cornual region of the uterus, with the proximal end of the
device near the endometrial-myometrial junction. In each case, the device
position shown on CT agreed with that previously shown on HSG.
In the single pelvic MRI study we identified, the Essure device produced
linear loss of signal in the regions of the fallopian tubes and about the
uterine cornua (Figs. 5A and
5B). The signal loss was most
prominent on gradient-echo sequences with blooming artifact, but was also
clearly present on T2-weighted fast spin-echo sequences.
Discussion
In the future, the Essure microinsert may become a more prevalent form of
female birth control. Most current methods of female sterilization (e.g.,
tubal ligation) require general anesthesia, laparoscopy, and small surgical
incisions, thus exposing the patient to the inherent risks of a surgical
procedure and requiring the patient to endure a significant period of
postoperative recovery. The Essure microinsert device, by contrast, is placed
transcervically in an outpatient setting. Placement into the fallopian tubes
is generally achieved via catheterization under hysteroscopic visualization of
the uterine cavity. Recently, placement under fluoroscopic guidance has also
been described [13]. At our
institution, sedation and analgesia during device placement is provided with
IV administration of propofol, fentanyl, and midazolam.
The Essure device has become an increasingly popular option in recent years
because of its minimally invasive method of placement, its high acceptance
rate, and its high degree of effectiveness
[14]. The largest published
series to date is the pivotal trial
[7]. In a cohort of 518
patients, placement occurred in 92%. Complications were uncommon— with
device expulsion in 3% and tubal perforation in 0.9%—and no pregnancies
occurred in 9,620 woman-months of follow-up. Although no randomized studies
compare Essure and laparoscopic tubal ligation, published studies show Essure
is associated with fewer risks than those associated with general anesthesia
(because most are performed with the patient under local anesthesia, with or
without sedation); less chance of unintended laparotomy; and less risk of
damage to the bowel, bladder, or intraabdominal vessels
[7,
15,
16]. Essure is also associated
with less postoperative pain, quicker recovery, and earlier return to work
[7]. Cost comparison data also
favor the Essure device [17,
18].
The primary role of radiology relates to confirming location and tubal
occlusion on HSG evaluation of the device
[10,
11]. Radiologists,
nevertheless, need to be familiar with the appearance of the device on
sonography, CT, and MRI because they are likely to encounter the devices in
clinical practice. The Essure device is readily identified with all three
techniques, and its correct location can be confirmed. Familiarity with the
device and its positioning should allow easy recognition of the device by its
imaging findings. The imaging appearance of the Essure device is likely to be
distinctive from surgical methods of tubal ligation. Because most tubal
ligations in the United States are performed with cautery, imaging would
probably not be able to identify the tubal ligation. To our knowledge, the
only metallic device currently in use for surgical tubal ligation is the
Filshie Clip (Avalon Medical Corp.). The Filshie Clip can be seen on CT as a
metallic structure [19], but
would normally be located on the fallopian tube and not in the cornual region,
as would the properly positioned Essure device.
Our study has several limitations. First, this is a retrospective study
with a small number of patients. In addition, our study is descriptive, and we
have not addressed the issue of whether the function of the device can be
adequately evaluated with sonography, CT, or MRI. Although it seems that the
position of the device can be adequately determined using these three
techniques, exact criteria for the correct position and whether position alone
is adequate to predict tubal occlusion are unknown. If visualization of the
position of the device on sonography was adequate, it could potentially
prevent the use of ionizing radiation to evaluate the device. Further research
is required, however, to answer this question. In addition, it is not clear
from this small number of patients whether the inner coil can be reliably
distinguished from the outer coil by any of the three imaging methods, or
whether this distinction will be necessary clinically. Our MRI experience with
the device is still quite limited; however, an in vitro study found that the
device was MRI-safe up to 1.5 T
[20]. Finally, because the
placement of the Essure microinsert is relatively new at our institution, we
have only limited follow-up regarding pregnancy in patients who have had this
device placed. No pregnancies, however, have been reported to date in our
study group after 10-26 months of clinical follow-up.
In summary, the proximal portion of the Essure microinsert device is
evident sonographically as two slightly curvilinear parallel echogenic lines
in the cornual region of the uterus. On CT, the device appears as a linear
metallic density. On MRI, the device produces linear loss of signal along the
fallopian tubes related to metallic artifact. Recognition of the normal
expected appearance and location of the device will hopefully facilitate
accurate interpretation when these devices are incidentally encountered during
pelvic sonography, CT, or MRI performed for other reasons. Whether these
techniques will have a more routine role in evaluating these devices is not
yet known.
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Abstract
Introduction
