Objective
The objective of the study was to compare the vaginal apex pullout distance using 2 vs 3 suspension sutures during transvaginal uterosacral ligament suspension (USLS) and to describe relationships to ipsilateral ureter and nerve structures.
Study Design
Eight fresh-frozen female cadavers were studied. After hysterectomy, a transvaginal USLS was performed with placement of 3 suspension sutures per side. The 2 most distal sutures on each ligament were tied. A screw-and-washer attachment was secured in the middle of the vaginal cuff and tied to a pulley system with surgical filament. Distal traction was applied with sequentially increasing weight loads. Distal migration of the vaginal apex from baseline with each weight load was recorded. The most proximal suspension suture was tied and the procedure repeated. Horizontal distances between each USLS suture to the ipsilateral ureter were measured. Three discrete points were marked on sacral nerves S1-S3, and the shortest distance between each point and each ipsilateral USLS suture was measured. Descriptive statistics and repeated-measures analysis of variance were performed.
Results
Application of each load resulted in greater migration distances for the 2 suture configuration when compared with 3 sutures ( P < .05). Differences were greatest for the 3 kg load (mean ± SEM, 2.0 ± 0.2 vs 1.5 ± 0.1 cm, respectively). Distances to ipsilateral ureter between the 2 most cranial sutures were comparable ( P > .05). The most cranial USLS suture was closest to sacral nerves S1-S3.
Conclusion
In this cadaveric study, 3 USLS sutures provided more support to the vaginal apex than 2 sutures, although the absolute difference may not be clinically significant. The most cranial suture had the smallest distances to sacral nerves S1-S3.
The uterosacral ligament suspension (USLS) is a procedure performed for the correction of prolapse of the vaginal apex. The procedure consists of fixing the vaginal apex to the uterosacral ligaments bilaterally at or above the level of the ischial spines using interrupted sutures. The procedure is safe overall and associated with favorable outcomes. However, possible complications during suspension suture placement include injury to structures present in close proximity to the uterosacral ligaments, including the ureters and sacral nerves.
Ureteral involvement has been reported to be up to 11%, whereas the reported sacral neuropathy incidence is up to 6.9%. Variations in procedural technique exist, including approach (ie, transvaginal, abdominal, laparoscopic), type of suture material (ie, permanent versus absorbable), and number of suspension sutures placed per ligament. There is scant information in the literature regarding procedure efficacy and safety related to the number of suspension sutures used. A higher number of sutures may provide more support to the vaginal cuff, whereas a lower number of suspension sutures may be associated with a lower risk of ureteral or sacral nerve injury.
The objective of our study was to compare vaginal apex strength (as a measure of procedure efficacy) using 2 vs 3 suspension sutures during transvaginal USLS and to describe the anatomic relationships to the ureter and nerve structures near the suspension sutures.
Materials and Methods
Eight fresh female cadavers were obtained from the Willed Body Program at the University of Texas Southwestern Medical Center in Dallas. Exemption from institutional review board approval was obtained in accordance with the Code of Federal Regulations, Title 45, Part 36, subpart 101 (b) (1).
The age, race, height, weight, and cause of death were recorded. For each cadaver, after hysterectomy, a transvaginal USLS was performed by passing 3 sutures (1 0-polyglactin 910 followed by 2 2-0 polyester sutures) through each uterosacral ligament (USL), starting at the level of the ischial spine and moving cranially along the ligament at 1 cm intervals similar to that described by Shull et al.
The sutures were passed through the anterior and posterior vaginal cuff, respectively, distributed evenly along the entire width of the cuff. To study the differences between using 2 vs 3 sutures bilaterally in each cadaver, the 2 more caudal sutures (suture 2 [middle] and suture 1 [most caudal]) on each uterosacral ligament were tied first, leaving the most cranial suture (suture 3) on each side untied and held individually with hemostats for subsequent tying and testing. All sutures were placed by the primary author (T.I.M.), who is right handed, with placement visualized and in agreement by the senior author (C.Y.W.).
After the cuff was closed, a 9/16 inch (14 mm) diameter metal metric fender washer (Servalite, East Moline, IL) was placed above the vaginal cuff. A 1/8 inch diameter bolt (Servalite) was threaded through the washer and passed through the center of the cuff and out the vagina in which it was affixed to a number 7 waxed polyester surgical filament (catalog no. 761403; Dodge, Cambridge, MA). This same filament has been used in previous studies and resists forces greater than 38 pounds per square inch without deformation. The surgical filament was oriented parallel to the table’s surface using a carpenter’s level and passed over a 3 inch fixed single pulley (National, Sterling, IL) attached at the table’s end by 2 2½ inch, 3-way edging clamps (Pony, Chicago, IL) as described previously. Successive 500 g slotted weights (Rice Lake Weighing Systems, Rice Lake, WI) were added to a weight hanger to provide increasing loads of 0.5, 1, 1.5, 2, 2.5, and 3 kg against the vaginal cuff.
The measurements of the distance traversed by the vaginal apex and supported by the 2 suture configuration from a baseline position after application of each weight load were recorded. On the same cadaver, the tagged remaining most cranial uterosacral ligament sutures on each side (suture 3) were subsequently tied, and the distances traversed with each weight load were measured to evaluate the effect of 3 sutures placed bilaterally on the support of the vaginal apex.
The site of attachment of each suspension suture on the uterosacral ligaments was marked on each side after application of the suspension sutures. Prior to tying the sutures and performing weight load testing, measurements were taken from each suture on the uterosacral ligaments to the following structures: smallest horizontal distance to ipsilateral ureter; smallest distance to ipsilateral sacral nerves S1, S2, and S3 at 3 discrete points along each nerve: sacral foramen (point a), 1 cm distal to sacral foramen (point b), and 2 cm distal to sacral foramen (point c) ( Figure 1 ). Data were analyzed using repeated measures analysis of variance using SAS version 9.2 (SAS Institute, Cary, NC).
Results
The mean ± SEM age of the cadavers was 88 ± 3 years (range, 77–103), and the mean body mass index (BMI) was 22 ± 2 kg/m 2 (range, 14–29). All 8 were white, and the most common cause of death was from cardiopulmonary causes (4 of 8; 50%). The mean total vaginal length was 8.6 ± 0.2 cm.
Distance moved by apex
The distal migration of the vaginal cuff for each weight load with 2 and 3 sutures per side is illustrated in Figure 2 . With the exception of the 0.5 kg load, application of each load in this study resulted in significantly greater migration distances for the 2-suture configuration when compared with 3 sutures. The differences between the 2 were greatest for the 3 kg load, with the 2-suture configuration moving a mean (±SEM) distance of 2.0 ± 0.2 cm compared with a distance of 1.5 ± 0.1 cm for 3 sutures ( P = .030). For one of the specimens, the apex descended a distance as large as 2.7 cm for the 2-suture configuration.
Location with respect to ureter
Distances from each of the 3 uterosacral ligament sutures to the ipsilateral ureter were not significantly different between the left and right ( Figure 3 ). Of the 3 levels of sutures (cranial to caudal), the most caudally placed sutures on each uterosacral ligament were located significantly closer to the ureters than either of the 2 more cranially placed sutures, with a mean distance of 1.0 ± 0.2 cm on the right and 1.4 ± 0.3 cm on the left. There was no significant difference in proximity to the ureters between the 2 most cranial sutures (ie, between suture 3 vs suture 2).
Sacral nerve anatomy
The proximity of each uterosacral ligament suture to 3 discrete points along sacral nerves S1, S2, and S3 (at the nerve root as they exited the sacral foramina [point a], and at 1 cm [point b] and 2 cm [point c] from the foramina along the nerve) was examined ( Table ).
| Sacral nerve | Point | Suture 3 (cranial) | Suture 2 | Suture 1 (caudal) | |||
|---|---|---|---|---|---|---|---|
| Right | Left | Right | Left | Right | Left | ||
| S1 | a | 4.1 ± 0.6 | 3.7 ± 0.5 | 4.7 ± 0.7 a | 4.4 ± 0.6 a | 5.1 ± 0.6 b | 4.8 ± 0.6 b |
| b | 3.6 ± 0.5 | 3.7 ± 0.5 | 4.1 ± 0.5 a | 4.2 ± 0.6 a | 4.6 ± 0.5 b | 4.6 ± 0.6 b | |
| c | 3.6 ± 0.5 | 3.5 ± 0.6 | 4.1 ± 0.6 a | 3.8 ± 0.7 a | 4.5 ± 0.5 b | 4.1 ± 0.6 b | |
| S2 | a | 3.2 ± 0.6 | 3.4 ± 0.4 | 3.7 ± 0.6 a | 4.1 ± 0.5 a | 3.8 ± 0.5 b | 4.2 ± 0.6 b |
| b | 2.9 ± 0.5 | 3.2 ± 0.5 | 3.3 ± 0.5 a | 3.7 ± 0.5 a | 3.6 ± 0.4 b | 3.9 ± 0.6 b | |
| c | 2.6 ± 0.3 | 2.9 ± 0.6 | 3.1 ± 0.4 a | 3.5 ± 0.5 a | 3.4 ± 0.3 b | 3.8 ± 0.6 b | |
| S3 | a | 2.1 ± 0.2 | 3.0 ± 0.3 | 2.9 ± 0.3 a | 3.4 ± 0.4 a | 3.3 ± 0.2 b | 3.7 ± 0.4 b |
| b | 2.4 ± 0.4 | 2.7 ± 0.3 | 3.1 ± 0.3 a | 3.3 ± 0.4 a | 3.6 ± 0.3 b | 3.8 ± 0.4 b | |
| c | 2.4 ± 0.3 | 2.6 ± 0.3 | 3.0 ± 0.3 a | 3.0 ± 0.3 a | 3.5 ± 0.2 b | 3.5 ± 0.4 b | |
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