Permanent Contraception: Utilizing Transvaginal Ultrasonography to Confirm Appropriate Insert Placement
Hector Chapa, MD, FACOG
According to the Center for Disease Control’s National Survey of Family Growth, (2011 to 2013) among women aged 15 to 44 years of age who are currently using contraception, 25.1% are using female sterilization as their birth control option, with 25.9% choosing the oral contraceptive pill (1). Traditionally, female permanent contraceptive procedures involved a laparoscopic approach for tubal occlusion. In 2002, the US Food and Drug Administration (FDA) approved the first medical device for hysteroscopic sterilization, the Essure® permanent birth control system (Bayer, Whippany, NJ; USA). This contraceptive method places nitinol/polyethylene terephthalate (PET) based micro-inserts into the tubal lumens via the uterine cavity (Figure 1).
Figure 1: Ideal position of the micro-insert. UTJ=uterotubal junction; SUTJ= serosal uterotubal junction
These PET fibers elicit a natural response which leads to tissue in-growth within the tubal lumen resulting in tubal blockade. This tissue response occurs within the ensuing 12 weeks after insert placement. Alternative methods of contraception must be used during this 12-week interval. Reliance upon the micro-inserts for contraception requires performance of a confirmation test at 12 weeks after placement. Since first approved in 2002, a modified (low volume – low pressure) hysterosalpingogram (HSG) has been considered the definitive test for determining ability to rely. However, in July 2015, the US FDA approved the use of transvaginal ultrasound (TVU) as an alternate confirmation test for the Essure system (2).
Confirmation tests after bilateral insert placement
A confirmation test should be performed 12 weeks after bilateral insert placement to evaluate insert retention and location. Reliance upon the micro-inserts for contraception requires performance of a confirmation test at 12 weeks after placement. Previously, a modified HSG was the only approved method for the confirmation test in United States. Also, repetitive from the last paragraph: Since first approved in 2002, a modified (low volume – low pressure) hysterosalpingogram (HSG) has been considered the definitive test for determining ability to rely. Now, since 2015, transvaginal ultrasonography (TVU) has been FDA approved as an alternative confirmation test. Again, repetitive from the last paragraph: However, in July 2015, the US FDA approved the use of transvaginal ultrasound (TVU) as an alternate confirmation test for the Essure system (2). The availability of TVU does not replace or eliminate the option of the modified HSG. Rather, TVU is an equivalent alternative should the patient meet inclusion criteria for its use. Up to 85% of patients who undergo TVU will not require additional imaging. Up to 15% of patients who undergo TVU confirmation testing will ultimately require a modified HSG due to inability to determine reliance based on TVU. Even if a patient meets TVU requirements, both options for confirmation testing should be offered, with the patient selecting her choice of test.
TVU compared to modified HSG
Both methods have their respective advantages and disadvantages. Among the advantages of the modified HSG are its ability to identify insert location, as well as tubal occlusion (absence of contrast spillage through the tubes). However, this method exposes the patient to radiation exposure, must be performed in a radiological suite, and is more invasive than vaginal ultrasound. Additionally, absence of contrast spillage – while implying tubal occlusion – may in fact represent tubal ostial spasm leading to a false interpretation of tubal occlusion. However, the main advantage of the modified HSG is that it is considered the definitive (gold standard) confirmatory test as both location and occlusion are assessed. Alternatively, the advantages of transvaginal ultrasound include absence of radiation exposure, the ability to be performed in the physician’s own office, and its less invasive nature than HSG. An additional advantage is the ability to see the soft tissue and assess the relationship to the echogenic micro-inserts. TVU does not assess tubal occlusion. Ability to rely on the micro-inserts for contraception owing to performing TVU is based on the location of the inserts.
The TVU/HSG confirmation test algorithm
If the patient meets TVU procedure requirements and desires TVU, it may be performed as a first-line confirmation test (3). If the patient meets eligibility criteria but declines ultrasonography, then referral for modified HSG must occur. Healthcare providers who utilize the micro-insert confirmation test with TVU must complete specific training, which is administered by the medical device manufacturer (Bayer, Whippany, NJ, USA) and receive a certificate of training completion.
TVU should not be used as a micro-insert confirmation test under the following circumstances:
- Difficult placement procedure due to one or more of the following: concern at time of placement of possible perforation due to excessive force required, difficulty identifying the tubal ostia during placement due to anatomical variation or technical factors, or physician uncertainty about insert placement/location.
- Micro-insert placement procedure time greater than 15 minutes (scope in– scope out).
- Placement with zero or >8 trailing coils.
- Unusual post-operative pain, transient or persistent, or onset at some later time post procedure without other identifiable cause.
- Patients on active immunosuppressive therapy (e.g., systemic corticosteroids or chemotherapy).
Transvaginal Ultrasound Logistics
TVU confirmation testing should be performed only by an experienced gynecologist, ultrasonographer, and/or radiologist specifically trained in the TVU confirmation test. Basic transvaginal ultrasound skills are required including the ability to identify normal anatomy and pelvic structures with sagittal and transverse views of uterus. The American Institute of Ultrasound in Medicine (AIUM) provides practice guidelines for the performance of ultrasound of the female pelvis which can be accessed online (www.aium.org/resources/guidelines/femalepelvis.pdf). Patients qualifying and opting for TVU should be informed that up to 15% of scanned patients may require a modified HSG due to inability to allow reliance by ultrasound. These are cases in which the inserts cannot be classified as being in neither optimal nor satisfactory location by ultrasound (interpretation of TVU images for confirmation will be reviewed in a later section).
For proper image capture, remember “OIL”
Prior to discussing the specific TVU protocol, it is important to review the specific anatomical planes used during the ultrasound procedure. First, with the vaginal transducer in the sagittal plane, a sagittal midline image of the uterus must be obtained. This midline sagittal view determines the uterine orientation (the “O” in OIL) (Figure 2).
Figure 2: TVU midline sagittal view of the uterus for uterine ORIENTATION.
Knowing the orientation of uterus (midline, anteverted, or retroverted) is necessary in order to properly identify each insert. The correct midline sagittal view includes the entire endometrial stripe and endocervix as a continuous, linear echogenic line. The linear axis of either insert should NOT be visualized in this midline sagittal view. Suspect proximal placement if the linear axis is visualized in the uterine cavity, or suspect fundal perforation if the linear axis is visualized in the fundal myometrium. Trailing coils may be seen in the cavity, which is within normal limits depending on placement.
Secondly, with the transducer turned 90°, adjust the probe to visualize the maximum width of endometrium to obtain a transverse fundal view which allows for micro-insert identification (the “I” in OIL). This will later be identified as the "scout view” (Figure 3). Two inserts must be identified in one scout view. If only one micro- insert is identified in this scout view, the TVU should be stopped and the patient should be referred to modified HSG for final assessment. This scout view is the first of three required images which must be obtained and retained for proper documentation. Both inserts MUST be identified in the fundal transverse view to reduce risk of duplicate imaging.
Figure 3: TVU transverse fundal view for the “scout image” and micro-insert IDENTIFICATION Both inserts MUST be visualized in this image.
Lastly, location (the “L” in OIL) of each micro-insert must be determined. This location step will be used to determine whether or not the patient may rely on the inserts or be referred to modified HSG for final determination of reliance. Starting from the transverse fundal view, adjust the probe to focus on either cornua. Slight probe rotation to a transverse/oblique view will be required to visualize the linear axis of each insert. Capture these images, with each insert labeled “left” or “right” respectfully (Figure 4). These two images are the second and third required images for proper documentation.
Figure 4: LOCATION of both inserts must be determined. This linear axis of each insert must appear curvilinear, crossing the myometrium in the cornua OR in contact with the SUTJ.
Based on the “L” in OIL (each insert’s LOCATION), each insert will be assigned 1 of 3 possible location states: optimal, satisfactory, or unsatisfactory (Table 1). Both inserts must have EITHER an optimal or satisfactory location to recommend reliance. If either of these two location states is met by both inserts, she may discontinue alternative contraception and rely on the inserts. If, however, one or both of the inserts does not meet the criteria of optimal or satisfactory location, the patient must continue alternative contraception until a modified HSG makes the determination of whether reliance may be granted.
Table 1 Three possible locations of each micro-insert based on TVU transverse/oblique focused cornual views
Training certification program for TVU confirmation
Certification for training is required by the medical device manufacturer as well as the FDA prior to adopting TVU as a confirmation test alternative to modified HSG. Below are links to the educational resources available for completion of a TVU confirmation test training course:
- US department of health and human services. National health statistics report number 86: current contraceptive use and variation by selected characteristics among women age 15 to 44: United States, 2011 to 2013. 2015; (86):1-13
- www.prnnewswire.com. US FDA approves alternative contraception test for each your permanent birth control. July 1,2015. Accessed on Dec. 1,2016.
- Essure Instructions for use. Available at: www.hcp.essure-us.com. Accessed Dec. 1, 2016