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DOI:10.2214/AJR.05.1638
AJR 2006; 187:959-964
© American Roentgen Ray Society

Clinical Observations

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
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
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
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
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.


Figure 1
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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.

 
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.


Figure 2
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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.

 
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.


Figure 3
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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.

 


Materials and Methods
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 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
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
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 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
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.


Figure 4
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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).

 


Figure 5
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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.

 


Figure 6
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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.

 


Figure 7
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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).

 


Figure 8
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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).

 


Figure 9
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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).

 


Figure 10
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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).

 
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.


Figure 11
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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.

 


Figure 12
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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.

 
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
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
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.


References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

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  10. [No authors listed]. Essure physician training manual: HSG protocol. San Carlos, CA: Conceptus,2002
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  13. McSwain H, Shjaw C, Hall LD. Placement of the Essure permanent birth control device with fluoroscopic guidance: a novel method for tubal sterilization. J Vasc Interv Radiol 2005;16 : 1007-1012[Medline]
  14. Kerin JF, Carnignan CS, Cher D. The safety and effectiveness of a new hysteroscopic method for permanent birth control: results of the first Essure pbc clinical study. Aust N Z J Obstet Gynaecol2001; 41:364 -370[Medline]
  15. Jamieson DJ, Hillis SD, Duerr A et al. Complications of interval laparoscopic tubal sterilization: findings from US collaborative review of sterilization. Obstet Gynecol 2000;96 : 997-1002[Abstract/Free Full Text]
  16. Westoff C, Davis A. Tubal sterilization: focus on the US experience. Fertil Steril 2000;73 : 913-922[CrossRef][Medline]
  17. Creedon DJ, Hopkins MR, Williams AR, et al. Comparative cost-analysis of Essure hysteroscopic sterilization and laparoscopic bilateral fulguration. J Am Assoc Gynecol Laparosc2004; 3:S42 -S43
  18. Levie MD, Chudnoff SG. Office hysteroscopic sterilization compared with laparoscopic sterilization: a critical cost analysis. J Minim Invasive Gynecol 2005; 12:318 -322[CrossRef][Medline]
  19. Lok IH, Lo KW, Ng JS, et al. Spontaneous expulsion of a Filshie clip through the anterior abdominal wall. Gynecol Obstet Invest 2003; 55:183 -185[CrossRef][Medline]
  20. Shellock FG. New metallic implant used for permanent contraception in women: evaluation of MR safety. AJR2002; 178:1513 -1516[Abstract/Free Full Text]

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