Endovaginal Imaging: Vaginal Mesh and Implants

Fig. 9.1

Introital ultrasound image in midsagittal view showing the anterior mesh for anterior compartment repair. Bladder (B), symphysis (S) (from Tunn et al. [4], with permission)

Fig. 9.2

Introital ultrasound image in midsagittal view showing the posterior mesh for posterior compartment repair. Bladder (B), symphysis (S) (from Tunn et al. [4], with permission)

Velemir et al. examined mesh appearance postoperatively using introital 2D ultrasonography in patients who had undergone anterior and/or posterior vaginal wall prolapse surgery with the Prolift system. They concluded that severe mesh retraction leads to a lack of covering of the distal part of the vaginal walls, which is associated with posterior prolapse recurrence [6]. In addition, in a previous study aimed to explore the correlation between mesh appearance and success after 6 months of anterior vaginal mesh repair, the introital ultrasound approach was used and demonstrated that mesh retraction was significantly greater in patients who reported de novo overactive bladder and vaginal pain [25].

In the literature 2D, 3D, 4D perineal/introital techniques are widely reported to identify anatomic and dynamic aspects of vaginal polypropylene mesh implants [7, 26, 27]. The midsagittal plane provides views of the pubic bone, urethra, bladder, vagina, and rectoanal angle. The anterior and posterior vaginal wall meshes are identified in Figs. 9.3 and 9.4, respectively [26]. However, 2D perineal sonography depiction of the location of vaginal mesh kits may be difficult because of the distance to the mesh arms. Therefore, for these groups of patients, 3D or 4D perineal ultrasound may be helpful [28], and the endovaginal approach provides the greatest amount of information.

Fig. 9.3

2D translabial ultrasound image in sagittal plane showing the anterior vaginal wall (AVW) mesh. Bladder (Bl) (from Staack et al. [26], with permission)

Fig. 9.4

2D translabial ultrasound image in sagittal plane showing the posterior vaginal wall (PVW) mesh. Bladder (Bl), urethra (U), vagina (V), rectum (R) (from Staack et al. [26], with permission)

Endovaginal Approach

A recent study demonstrates that 3D endovaginal ultrasound (3D-EVUS) imaging May be the best tool to evaluate the presence, location, and extent of polypropylene mesh, especially in patients with a complicated treatment history [3]. 3D-EVUS has proven to have a high sensitivity for the detection of vaginal mesh or slings. As a result, it can explain the reason for complications or failure and aid to plan for further surgical intervention. Polypropylene mesh can be clearly identified with 3D-EVUS sonography, as it produces a distinct echogenic signal on sonography [5]. Polypropylene mesh appears as a thin echogenic wavy structure adjacent to the vaginal wall with minimal acoustic shadowing. The anterior mesh is demonstrated under the bladder neck and proximal urethra (Fig. 9.5) and the posterior mesh is demonstrated under vagina and transvaginal ultrasound probe (Fig. 9.6a, b). The advantage of multicompartment 3D ultrasound is the fact that the 3D data volume can be manipulated using a combination of straight and oblique planes to determine the intrapelvic course of mesh implants.

Fig. 9.5

(a) 3D endovaginal ultrasound image (anterior compartment) in sagittal plane showing the anterior vaginal wall mesh (M). Bladder (B), urethra (U), vagina (V), pubic symphysis (PS). (b) 3D Coronal tilted view of the posterior compartment obtained using an endovaginal probe. Arrows point to the edges of the posterior mesh. External anal sphincter (EAS), vagina (V), levator ani (LA), Anus (A)

Fig. 9.6

(a) 3D endovaginal ultrasound image (posterior compartment) in sagittal plane showing the posterior vaginal wall mesh (white arrows). Vagina (V), anorectum (AR), external anal sphincter (EAS), levator plate (LP); anterior (A), posterior (P), cephalad (C), left (L). (b) 3D endovaginal ultrasound image in midsagittal plane showing the posterior vaginal wall mesh prominence (white arrows). Vagina (V), anorectum (AR), levator plate (LP), anterior (A), posterior (P), cephalad (C), left (L), urethra (U). (c) 3D endoanal ultrasound image in midsagittal plane showing the posterior vaginal wall mesh in full length (yellow arrows point to the 58 mm cursors) past the apex of the vagina (V) (yellow line). Transducer (T) in anorectum, anterior (A), bladder (B), cephalad (C), urethra (U)

Endoanal Approach

Endoanal ultrasonography (EAUS) and endorectal ultrasonography (ERUS) are also useful in determining the location and extent of mesh implants. Endoanal ultrasound is especially useful in evaluating vaginal mesh kits when the upper vagina has collapsed. By using the endoanal approach, one can get past the short vagina and image the sacrospinous-sacrospinous mesh bridge created by the mesh (Fig. 9.6c). When a tight bridge exists, the operator has to be careful while advancing the probe should there be any resistance. Additionally, sometimes the endoanal approach may be better tolerated in patients with levator ani muscle spasm or myalgia. The folded anterior vaginal mesh is demonstrated in Fig. 9.7. Figure 9.8 shows posterior vaginal mesh located at perineum. A useful modality for visualization of mesh is the rendered view of the mesh (see Fig. 9.8b, c).

Fig. 9.7

360° 3D endoanal ultrasound image in sagittal plane showing the folding anterior vaginal wall mesh (yellow arrow). Bladder (V), urethra (U), vagina (V), anorectum (AR), levator plate (LP), anterior (A), posterior (P), cephalad (C), left (L)

Fig. 9.8

(a) 360° 3D endoanal ultrasound image in midsagittal plane showing the posterior vaginal wall mesh (yellow arrows) at perineum. Vagina (V), levator plate (LP), anterior (A), posterior (P), right (R). (b) 360° 3D endoanal ultrasound image in left parasagittal plane showing the posterior vaginal wall mesh (yellow arrows) with anterior extrusion. Levator plate (LP), anterior (A), posterior (P), right (R), cephalad (C), anterior (A). (c) 360° 3D endoanal ultrasound rendered image in left parasagittal plane showing the posterior vaginal wall mesh (yellow arrows) with anterior extrusion. The mesh is enhanced in the rendered post-processing. Levator plate (LP), anterior (A), posterior (P), right (R), cephalad (C). (d) Unprocessed view of a 3D endovaginal ultrasound volume cut in coronal plane showing the posterior vaginal wall mesh (outlined is the pathognomonic mesh lattice). In this view the vagina cannot be seen, as the image is looking posteriorly from inside the vagina. Anorectum (AR), levator ani muscle (levator M), anterior (A), cephalad (C), left (L), posterior (P), right (R). (e) Post-processed rendered view of a 3D endovaginal ultrasound volume cut in coronal plane showing the posterior vaginal wall mesh (outlined is the pathognomonic mesh lattice), the arrows point to the left mesh arm. In this view the vagina cannot be seen, as the image is looking posteriorly from inside the vagina. Note that the posterior mesh generally pulls away from the anal sphincter complex. Here a line is drawn to denote where the detached mesh is shrunken and coiled compared to the more superior aspect of the mesh. Anorectum (A), puborectalis (PR), iliococcygeus (IC), ischiorectal fat (IRF), cephalad (C), left (L), posterior (P), right (R). (f) 360° 3D endovaginal ultrasound volume midsagittal plane showing the left side of pelvis with anterior and posterior vaginal wall mesh. In this view the mesh in the anterior vagina is 1 mm and the posterior mesh is 2 mm (large arrows) from the vaginal epithelium. Vagina (V), anorectum (AR), anterior (A), cephalad (C), left (L), posterior (P), urethra (U), bladder (B). (g) 360° 3D endovaginal ultrasound volume midsagittal plane showing the left side of pelvis with posterior sacrocolpoperineopexy mesh (SCP) and a sling (S). In this view the SCP mesh is deeper than what is typically seen with vaginal mesh. Note that both the SCP and the sling mesh create acoustic shadowing the obscures underlying structures. Transducer (T), sling (S), bladder (B), anorectum (AR), anterior (A), cephalad (C), left (L), posterior (P). (h) 360° 3D endovaginal ultrasound volume midsagittal plane showing the bladder with an implanted mesh (arrows) and a growth at the trigone (denoted with Ca). The growth proved to be a neoplasm. Transducer (T), bladder (B), anterior (A), cephalad (C), bladder (B), urethra (U)

Mesh Complications and Ultrasonographic Findings

Transvaginal mesh has been used for POP repair for many years, and complications related to mesh have been widely reported. A Cochrane review reported an erosion rate of 10.3% after anterior vaginal wall repair with polypropylene mesh [29]. A systematic review from 2014 concluded that the mean total complication rate in anterior, posterior, and combined mesh repair are 8–27%, 3.5–20% and 13–40%, respectively [30]. Complications related to mesh in female pelvic floor surgery are classified according to the International Urogynecological Association (IUGA)/ International Continence Society (ICS) into (1) local complications, (2) complications to surrounding organs, and (3) systemic complications [31]. A recent retrospective multicenter chart review stated that the affected site of mesh complications could occur at the area or away from the suture line in 250 patients with TVM complications after POP surgery [32]. Ultrasound findings related to complications of TVM will be discussed according to the IUGA/ICS classification.

Mesh Contraction (Shrinkage)

One of the more disappointing aspects of vaginal mesh was the fact that it sometimes failed, especially in the anterior compartment. The anterior mesh kits such as the AMS Perigee did not have secure anterior anchoring points and bunched up (Fig. 9.9). Mesh contraction can be associated with the development of focally painful segments of hardened mesh. This phenomenon likely underlies the development of primary vaginal pain syndromes and dyspareunia following vaginal mesh use. Pain can usually be reproduced by palpation of the contracted mesh segment, typically along the apical mesh arms. Collagen deposition and contraction within the mesh pores may be responsible for mesh hardening and nerve fiber entrapment; another cause of this finding is over tensioning of the mesh arms during implantation. The main clinical features include severe vaginal pain with movement, dyspareunia, and focal tenderness over contracted portions of the mesh on vaginal examination. Exact etiology of shrinkage of synthetic mesh after implantation is most likely inflammation and tissue ingrowth, but different theories have been suggested. Graft shrinkage could be due to physical consequence of the inflammatory response to the mesh or result of inadequate tissue ingrowth into the mesh. There is growing evidence to suggest that synthetic mesh shrinks significantly once incorporated in the biological tissues.

Fig. 9.9

(a) 360° 3D endovaginal ultrasound rendered image showing the apical shrunken mesh and one arm of the mesh. Bladder (B). (b) 360° 3D endoanal ultrasound midsagittal image showing an anterior mesh that is flat (two yellow arrows). The patient has an apical symptomatic enterocele (hollow arrow). The physical exam is not significant. An apical sacrocolpopexy relieved patient of her symptoms. Bladder (B), transducer in anorectum (AR), pubic symphysis (PS), vagina (V), external anal sphincter (EAS)

There has been controversy as to whether or not mesh shrinkage and folding are continuous processes or are limited to the immediate post-operative period [4, 6, 33, 34]. The current consensus is that mesh folding and shrinkage are associated with complications and pain [9]. Based on this assumption, it has been proposed that together with investing in the development of new materials, the focus should also be on improving surgical technique and quality control in order to allow the mesh to be implanted flat and well spread out, anchored to underlying tissues, thus preventing immediate postoperative folding [9] but making the mesh flat requires tensioning it which in turn does not allow room for shrinkage of mesh. Ultrasound imaging is used to evaluate the appearance of polypropylene meshes on the significance of mesh shrinkage and folding. Moreover, 3D-EVUS can also be helpful in mapping meshes placed in multiple compartments when physical examination cannot exactly locate the existence of contraction. 3D-EVUS also nicely demonstrates the mesh arms to the sacrospinous ligaments. An arm under tension may be harder to see as it ropes (see Fig. 9.8d, e).

Mesh Extrusion

One of the more recognized complications related to vaginally placed mesh is mesh extrusion. Mesh extrusion is considered to be mesh visualized through the vaginal epithelium. Although standardized terminology now exists to describe complications such as mesh erosion or extrusion [35], the variability of the use of the term in the literature makes it difficult to identify exact exposure rates.

Mesh extrusion rates vary from 0 to 25% in different studies [36, 37]. A Cochrane review by Maher et al. [18] suggested that use of vaginal mesh was associated with an 11.4% rate of mesh extrusion and a 6.8% rate of surgical re-intervention. A non-significant increase in rates of vaginal mesh exposure and reoperation for vaginal mesh exposure after vaginal mesh surgery in comparison to laparoscopic sacrocolpopexy has also been recognized (13 vs 2%, P = 0.07 and 9 vs 2%, P = 0.11, respectively) [38]. Symptoms associated with mesh extrusion are not insignificant; they include pelvic pain, infection, de novo dyspareunia (painful sex for patient or partner), de novo vaginal bleeding, atypical vaginal discharge, and the need for additional corrective surgeries [22].

A number of risk factors for mesh extrusion have been identified. Patient factors such as smoking status and vaginal atrophy can affect both the tissue integrity and surgical site healing, making exposure in these individuals more likely [39, 40]. Some studies have recognized older age as a risk factor for exposure, but it is unclear if this association is due strictly to age or to the more advanced vaginal atrophy often seen in older women, especially since a number of studies have not found a difference in extrusion rates between younger and older women [41].

It was recognized early on in the adoption of vaginal meshes that factors related to the mesh itself were capable of increasing the risk of mesh exposure. The majority of studies evaluate the effect of mesh type on extrusion; however, it is reasonable to extrapolate from the effects to their use in prolapse mesh kits. These factors are primarily related to pore size and mesh materials. Polypropylene meshes with large pore size (type 4 meshes) are associated with a lower exposure rate than many of their predecessors, which were designed to be tightly woven or nonporous. Another risk factor for mesh exposure that is now recognized is the depth of the vaginal dissection prior to mesh placement. As evidenced by the recognized risk factors for mesh exposure, prevention of exposure is the optimal “management” strategy for these (and other) complications. Preventative measures include avoiding the above-mentioned risk factors wherever possible, such as the use of lighter-weight polypropylene materials with larger pore sizes, use of transverse vaginal incisions for vaginal dissection (rather than vertical or t-shaped vaginal incisions), avoidance of folding the mesh, appropriate thickness of dissection, and deferring mesh placement to a time remote from hysterectomy. That said, there are no long-term studies showing how long mesh extrusion can be prevented given the fact that it is implanted in the vesicovaginal or rectovaginal tissue that has an average thickness of 5 mm. Endovaginal ultrasound imaging has the added benefit of placing the probe adjacent to the area of interest. Ultrasound is the only imaging modality that can visualize mesh easily. It has higher sensitivity for detection of mesh presence when physical examination fails to visualize or palpate the mesh in the vaginal canal. The mesh implanted via sacrocolpoperineopexy looks different, as it is deep and anterior to the rectum (Fig. 9.8f, g).

Urinary Tract or Lower Gastrointestinal Tract Compromise or Perforation

Urinary tract and gastrointestinal tract complications after vaginal mesh surgery are less common than after surgery for the anti-incontinence sling [42]. The violation of the genitourinary system or the gastrointestinal tract by mesh is called erosion. Mesh complications involving the bladder and rectum represent the minority of cases reported [43–46]. Recently, there was increased interest regarding the association between the polypropylene mesh/slings and bladder cancer. Ostergard and Azadi suggested that since oncogenesis is related to the presence of a foreign body that causes the chronic inflammatory reaction, implantation of the polypropylene mesh may cause carcinogenesis many years later [47]. The possibility of such association has been raised and needs further surveillance. However, based on current evidence, the risk of carcinogenesis related to polypropylene mesh is low [48–50]. Regardless, if a foci of cancer that needs to be resected or removed is close to the underlying mesh, the intervention may be complicated. 3D-EVUS can easily demonstrate uroepithelial masses on the trigonal area (see Fig. 9.8h).

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