Three-Dimensional Endovaginal Sonography of Synthetic Implanted Materials in the Female Pelvic Floor

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1 PICTORIAL ESSAY Three-Dimensional Endovaginal Sonography of Synthetic Implanted Materials in the Female Pelvic Floor Lindsay Denson, BS, RDMS, S. Abbas Shobeiri, MD The objective of this pictorial essay is to emphasize the ability of 3-dimensional endovaginal sonography to image synthetic implanted materials in the female pelvic floor. Implanted materials discussed in this pictorial essay include polypropylene vaginal mesh, polypropylene suburethral slings, and urethral bulking agents. Three-dimensional endovaginal sonography allows for more detailed imaging compared to computed tomography and magnetic resonance imaging of the female pelvic floor, in that each plane can be manipulated to show unique images of synthetic implanted materials. Key Words genitourinary ultrasound; pelvic floor imaging; synthetic implanted materials; 3-dimensional endovaginal sonography Received June 12, 2013, from the Department of Obstetrics and Gynecology, Section of Female Pelvic Medicine and Reconstructive Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma USA. Revision requested July 8, Revised manuscript accepted for publication July 25, Address correspondence to S. Abbas Shobeiri, MD, Department of Obstetrics and Gynecology, Section of Female Pelvic Medicine and Reconstructive Surgery, University of Oklahoma Health Sciences Center, 920 Stanton L. Young Blvd, PO Box 26901, WP2410, Oklahoma City, OK USA. Abbreviations 3D, 3-dimensional doi: /ultra I ndustry strives to produce ideal implantable materials to treat both pelvic organ prolapse and stress urinary incontinence. The ideal material would be sterile, biocompatible, noncarcinogenic, nonimmunogenic, and sustainable. 1 3 In an effort to find an ideal material, numerous types of implantable materials, biological and synthetic, have been used to alleviate pelvic organ prolapse and stress urinary incontinence symptoms. This pictorial essay contains 3-dimensional (3D) images of common synthetic implantable materials used to treat pelvic organ prolapse and stress urinary incontinence. Three-dimensional endovaginal sonography can reliably visualize anterior and posterior compartment structures. 4,5 Endovaginal imaging has the added benefit that it places the probe adjacent to the area of interest. Sonography is the only imaging modality that can visualize mesh and urethral bulking materials. With excessive use of mesh material for pelvic reconstruction, the US Food and Drug Administration issued a warning pertaining to the use of these materials. 6 A large number of these implanted materials have had to be removed. 7 Imaging the material before removal can guide the surgeon to tailor surgery appropriate for the patient. Although the procedure used to obtain these images is similar to the traditional endovaginal sonographic examination, the way the images are obtained is different. The traditional endovaginal transducer used in most gynecologic imaging is an end-fire transducer by the American Institute of Ultrasound in Medicine J Ultrasound Med 2014; 33:

2 The images in this pictorial essay were obtained with a sidefire transducer to allow for optimal imaging of the vaginal wall, urethra, and anal canal. The side-fire transducer allows the crystals to be directly adjacent to the vaginal wall for the entire length of the transducer footprint. A higher frequency can be used because very little depth penetration is necessary. All images were obtained with a BK Medical (Peabody, MA) 8838 high-resolution, 6 12-MHz, 360 rotational transducer (Figure 1). The 8838 has a mm acoustic footprint and penetration depth of up to 85 mm. This transducer is similar in size and shape to the traditional end-fire transducer used in gynecologic imaging. The preparation for both the patient and the transducer is similar to that for traditional endovaginal imaging. Although not necessary for imaging purposes, the patient is asked to have a comfortable amount of urine in her bladder before the procedure for patient comfort. The patient is placed in the dorsal lithotomy position with the hips flexed and abducted. As with any other ultrasound transducer, it is important to adequately cover the entire footprint with ample gel. Since the 8838 transducer is a side-fire transducer, care should be taken to apply gel down the length of the footprint in addition to the end of the transducer, as is done with an end-fire probe. A transducer cover or nonlubricated condom should be placed over the transducer and secured with a rubber band after ensuring that no air bubbles in the gel are present. Ample gel should be applied to the outside of the probe cover. The transducer is gently inserted to a depth of 6 cm into the vaginal canal in a neutral position such that pressure on the urethra and the anal canal is minimized (Figure 2). Although dynamic imaging may be valuable in certain circumstances during pelvic floor imaging, the volumes obtained to assess implantable materials are obtained while the patient is in a resting state. Pressing the 3D acquisition button moves the internal probe components. The system captures images every 0.5 for 360. The images are packaged into a multiplanar 3D volume that can be manipulated in all planes. Three-dimensional endovaginal sonography takes 30 seconds and minimizes patient discomfort. Sonography is operator dependent, but 3D imaging allows for an automated acquisition, which reduces operator dependence. If the acquisition is initiated just above the bladder neck and no movement disturbs the acquisition, only 1 volume set would be sufficient for optimal imaging. The data set can be exported via DVD/USB and stored on a server. The data can later be manipulated and analyzed with the use of BK software. The data volume can be manipulated on or off axis to improve imaging of off-axis structures. This process allows for superior imaging compared to computed tomography or magnetic resonance imaging for irregularly shaped structures seen in this pictorial essay, such as slings, urethral bulking agents, and deviated urethras. The images contained in this pictorial essay were obtained using the 360 Evus Sagittal preset. With this preset, the B-gain was 50%, brightness was 50%, and contrast was 50%. The extent was 360. Spacing was 0.55 degrees, and the direction of acquisition was clockwise. The total time of acquisition was 30.8 seconds, and total frames were 655. Figure 1. BK Medical 8838 high-resolution, 6 12-MHz, 360 rotational transducer. Arrows indicate the transducer footprint and where gel should be applied. Figure 2. BK Medical 8838 transducer inserted in the vaginal canal in a neutral position. Although this image shows a loose probe cover, we recommend securing the cover with a small rubber band. 522 J Ultrasound Med 2014; 33:

3 Figure 3. Endovaginal 3D volume obtained with the BK Medical 8838 transducer showing anterior and posterior polypropylene vaginal mesh (arrows). a, Patient s left sagittal view; b, coronal view; c, axial view. AC indicates anal canal; B, bladder; S, sling; T, transducer; U, urethra; *, sagittal plane; ^, coronal plane; and ~, axial plane. The following implanted materials can optimally be imaged by using the 3D sonographic technology: Vaginal Mesh Polypropylene transobturator and transitioanal mesh is used to treat pelvic organ prolaspe. 8 Polypropylene mesh cannot be adequately imaged with radiography, computed tomography, or magnetic resonance imaging. 9 Polypropylene mesh produces a distinct echogenic signal on sonography. Noncontracted polypropylene mesh appears as a thin echogenic wavy structure adjacent to the vaginal wall with minimal acoustic shadowing. Both anterior and posterior vaginal mesh can be clearly imaged with 3D sonography (Figure 3). A schematic of posterior vaginal mesh is depicted in Figure 4. Vaginal Mesh Extrusion Mesh extrusion is one of the main complications associated with polypropylene mesh implants. 1,12 It has been speculated that mesh extrusion is caused by mesh contraction. 9 This speculation has yet to be proven. Mesh extrusion appears as an echogenic wavy structure protruding through the vaginal wall (Figure 7). The patient in Figure 7 had Figure 4. Schematic of a sagittal view on endovaginal 360 sonography showing posterior polypropylene vaginal mesh (arrows). AVW indicates anterior vaginal wall; LP, levator plate; PS, pubic symphysis; PVW, posterior vaginal wall; and R, rectum; other abbreviations are as in Figure 3. Vaginal Mesh Contraction Polypropylene mesh has been shown to contract as early as 6 weeks after implantation. 8,10 Intraoperative and postoperative stresses may contribute to contraction, but it is speculated that inflammatory processes cause the contraction seen with polypropylene vaginal mesh. 8,9,11 Vaginal mesh contraction appears slightly more hyperechoic and thicker, with more acoustic showing, than noncontracted mesh (Figure 5). The patient in Figure 5 had dyspareunia and was scanned 4 years after mesh placement. The mesh was later surgically removed. A schematic of anterior mesh contraction is depicted in Figure 6. J Ultrasound Med 2014; 33:

4 Figure 5. Endovaginal 3D volume obtained with the BK Medical 8838 transducer showing contracted anterior polypropylene vaginal mesh (arrows). a, Patient s left sagittal view; b, coronal view; c, axial view. Abbreviations and symbols are as in Figure 3. dyspareunia; 0.5 cm of exposed mesh was seen on visual examination. Additional investigations of the accuracy of measuring mesh extrusion on sonography may prove beneficial in the future. Visualization of the extent of the mesh present, contracture, and folding assists in surgical planning. The mesh visualized here was later surgically removed. A schematic of posterior vaginal mesh extrusion is depicted in Figure 8. Figure 6. Schematic of a sagittal view on endovaginal 360 sonography showing contracted anterior polypropylene vaginal mesh (arrows). Abbreviations are as in Figures 3 and 4. Tension-Free Vaginal Tape Retropubic Midurethral Sling Tension-free vaginal tape is considered the reference standard in stress urinary incontinence treatment. 13 Tensionfree vaginal tape slings are appealing because they are effective and minimally invasive. 14 A tension-free vaginal tape polypropylene sling appears as an echogenic structure under the urethra. A schematic of a polypropylene urethral sling is depicted in Figure 9. As with vaginal mesh, the sling will produce an acoustic shadow (Figure 10a). The lateral portions of the sling produce the same echogenic signal and shadow (Figure 10b). A larger portion of the sling can be depicted in a single image when the coronal plane is manipulated (Figure 10c). Manipulation allows for material that follows an off-axis course to be depicted in a single image. A larger portion of the sling can also be seen in the axial plane (Figure 10d). A tension-free vaginal tape sling creates a seagull shape (Figure 10c). Transobturator Midurethral Sling Transobturator midurethral slings were developed to avoid the complications seen with retropubic slings. 14 A transobturator midurethral sling, also composed of polypropylene, produces the same echogenic signal with shadowing beneath the urethral as a tension-free vaginal tape sling (Figure11a). Because of the shape of the sling, only a small portion of the sling can be seen in the coronal plane (Figure 11b). Almost the entire length of the sling can be imaged in the axial plane. A transobturator midurethral sling also produces a seagull shape on sonography (Figure 11c). 524 J Ultrasound Med 2014; 33:

5 Figure 7. Endovaginal 3D volume obtained with the BK Medical 8838 transducer showing posterior polypropylene vaginal mesh (arrowheads) extruding through the vaginal wall (arrows). a, Patient s left sagittal view; b, coronal view; c, axial view. Abbreviations and symbols are as in Figure 3. Mini-Sling A mini-sling is also a midurethral sling that was introduced in an attempt to avoid the complications associated with the retropubic and transobturator blind trocar routes. 14 A mini-sling has more of a U-shaped appearance compared to the tension-free vaginal tape and transobturator mid - urethral slings seagull appearance (Figure 12). As previously described, a plane can be manipulated to allow for off-axis imaging. In this case, the sagittal plane was manipulated to allow for a deviated urethra to be depicted in its entirety in a single image (Figure 12a). Figure 8. Schematic of a sagittal view on endovaginal 360 sonography showing posterior polypropylene vaginal mesh extrusion (arrows). Abbreviations are as in Figures 3 and 4. Figure 9. Schematic of a sagittal view on endovaginal 360 sonography showing a polypropylene sling (arrows). Abbreviations are as in Figures 3 and 4. J Ultrasound Med 2014; 33:

6 Figure 10. Endovaginal 3D volume obtained with the BK Medical 8838 transducer showing a polypropylene tension-free vaginal tape retropubic midurethral sling (arrowheads). a, Patient s left sagittal view; b, coronal view; c, axial view; d, axial view. Arrows indicate pubic bone; abbreviations and symbols are as in Figure 3. Figure 11. Endovaginal 3D volume obtained with the BK Medical 8838 transducer showing a polypropylene transobturator midurethral sling (arrowheads). a, Patient s left sagittal view; b, coronal view; c, axial view. Abbreviations and symbols are as in Figure J Ultrasound Med 2014; 33:

7 Figure 12. Endovaginal 3D volume obtained with the BK Medical 8838 transducer showing a polypropylene midurethral mini-sling (arrowheads). a, Patient s left sagittal view; b, coronal view; c, axial view. Abbreviations and symbols are as in Figure 3. Urethral Bulking Agents Urethral bulking agents are used as alternatives to surgery to treat stress urinary incontinence. There are several bulking agent options to choose from. Currently, silicone-, calcium-, zirconium-, polyacylamide-, and collagen-based agents are used. 15 The echogenicity of a urethral bulking agent is determined by the composition of the bulking material. The signal from a calcium-based agent will produce a hyperechoic structure at the urethrovesical junction (Figure 13). 16 A schematic of an injected urethral bulking agent is depicted in Figure 14. Multiple Implanted Materials Recurrent stress urinary incontinence may be addressed by implanting multiple materials. Urethral bulking agents are oftentimes used as secondary treatments for recurrent stress urinary incontinence. 2 They are frequently seen in the presence of other materials previously used in an attempt to alleviate symptoms of stress urinary incontinence (Figure 15). Polypropylene slings and polypropylene vaginal mesh can also be commonly seen in a single image (Figures 3a, 5a, 7a, and 10a). Figure 13. Endovaginal 3D volume obtained with the BK Medical 8838 transducer showing a urethral bulking agent. a, Patient s left sagittal view; b, coronal view; c, axial view. Abbreviations and symbols are as in Figure 3. J Ultrasound Med 2014; 33:

8 Conclusions Management of implanted material complications has become a part of urogynecologic practice. However, even though ultrasound machines are readily available in urologic and gynecologic practices, imaging modalities are rarely used to image implantable materials by practitioners. A 2-dimensional endovaginal transducer can also be used to obtain meaningful images. This article highlights the capabilities of 3D high-definition endovaginal sonography in visualization of implanted materials. References Figure 14. Schematic of a sagittal view on endovaginal 360 sonography showing a urethral bulking agent (UBA). Other abbreviations are as in Figures 3 and Herschorn S. The use of biological and synthetic materials in vaginal surgery for prolapse. Curr Opin Urol 2007; 17: Davis NF, Kheradmand F, Creagh T. Injectable biomaterials for the treatment of stress urinary incontinence: their potential and pitfalls as urethral bulking agents. Int Urogynecol J 2013; 24: Cervigni M, Natale F. A comprehensive view on the actual trend in pelvic organ prolapse repair. Abdom Imaging 2013; 38: Figure 15. Endovaginal 3D volume obtained with the BK Medical 8838 transducer showing 2 polypropylene transobturator midurethral slings and urethral bulking material (UB). a, Patient s left sagittal view; b, coronal view; c, axial view; d, axial view. Arrowheads indicate inferior sling; and arrows, superior sling; other abbreviations and symbols are as in Figure J Ultrasound Med 2014; 33:

9 4. Rostaminia G, White DE, Quiroz LH, Shobeiri SA. Visualization of periurethral structures by 3D endovaginal ultrasonography in midsagittal plane is not associated with stress urinary incontinence status. Int Urogynecol J 2013; 24: Shobeiri SA, White D, Quiroz LH, Nihira MA. Anterior and posterior compartment 3D endovaginal ultrasound anatomy based on direct histologic comparison. Int Urogynecol J 2012; 23: US Food and Drug Administration. Surgical Mesh for Treatment of Women With Pelvic Organ Prolapse and Stress Urinary Incontinence: FDA Executive Summary. Silver Spring, MD; US Food and Drug Administration; Zimmerman CW, Theobald P, Braun NM. Exposure and erosion of vaginal meshes: etiology and treatment. In: New Techniques in Genital Prolapse Surgery. London, England: Springer; 2011: Tunn R, Picot A, Marschke J, Gauruder-Burmester A. Sonomorphological evaluation of polypropylene mesh implants after vaginal mesh repair in women with cystocele or rectocele. Ultrasound Obstet Gynecol 2007; 29: Svabik K, Martan A, Masata J, El-Haddad R, Hubka P, Pavlikova M. Ultrasound appearances after mesh implantation: evidence of mesh contraction or folding? Int Urogynecol J 2011; 22: Dietz HP, Erdmann M, Shek KL. Mesh contraction: myth or reality? Am J Obstet Gynecol 2011; 204:173.e1 173.e Velemir L, Amblard J, Fatton B, Savary D, Jacquetin B. Transvaginal mesh repair of anterior and posterior vaginal wall prolapse: a clinical and ultrasonographic study. Ultrasound Obstet Gynecol 2010; 35: Corton MM. Critical anatomic concepts for safe surgical mesh. Clin Obstet Gynecol 2013; 56: Nosti PA, Iglesia CB. Medicolegal issues surrounding devices and mesh for surgical treatment of prolapse and incontinence. Clin Obstet Gynecol 2013; 56: Barber MD, Weidner AC, Sokol AI, et al. Single-incision mini-sling compared with tension-free vaginal tape for the treatment of stress urinary incontinence: a randomized controlled trial. Obstet Gynecol 2012; 119: Zoorob D, Karram M. Bulking agents: a urogynecology perspective. Urol Clin North Am 2012; 39: Hegde A, Smith AL, Aguilar VC, Davila GW. Three-dimensional endovaginal ultrasound examination following injection of Macroplastique for stress urinary incontinence: outcomes based on location and periurethral distribution of the bulking agent. Int Urogynecol J 2013; 24: J Ultrasound Med 2014; 33: