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Neurovascular anatomy of the sacrospinous ligament region in female cadavers: Implications in sacrospinous ligament fixation
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Neurovascular anatomy of the sacrospinous ligament region in female cadavers: Implications in sacrospinous ligament fixation Shayzreen M. Roshanravan, MD; Cecilia K. Wieslander, MD; Joseph I. Schaffer, MD; Marlene M. Corton, MD OBJECTIVE: The objective of the study was to further characterize the anatomy of the coccygeus muscle–sacrospinous ligament (C-SSL) complex and to correlate the findings with sacrospinous ligament fixations (SSLF). STUDY DESIGN: Dissections were performed in 21 female cadavers. RESULTS: In all dissections, nerves originating from S3, S4, S5, or a
combination passed over the anterior surface of the C-SSL at its midsegment, and either the pudendal or third sacral nerve coursed on the superior border of C-SSL at its midpoint. In 100% of specimens, the internal pudendal artery (IPA) passed behind or just medial to the is-
chial spine. The average distance of the inferior gluteal artery (IGA) from the ischial spine and the superior border of the C-SSL was 24.2 (range, 15-35) mm and 3.4 (range, 1-5) mm, respectively. CONCLUSION: Nerves to the coccygeus and levator ani coursed over the midportion of the C-SSL where SSLF sutures are placed. The pudendal nerve and IGA were in proximity to the superior border of the C-SSL at its midportion, whereas the IPA passed behind the ischial spine, lateral to the recommended site for suture placement.
Key words: inferior gluteal artery, nerve to coccygeus, nerve to levator ani, pudendal nerve, sacrospinous ligament
Cite this article as: Roshanravan SM, Wieslander CK, Schaffer JI, et al. Neurovascular anatomy of the sacrospinous ligament region in female cadavers: Implications in sacrospinous ligament fixation. Am J Obstet Gynecol 2007;197:660.e1-660.e6.
F
ixation of the vaginal vault to the sacrospinous ligament (SSL) was initially described by Richter in 19681 and introduced in the United States by Randall and Nichols in 1971.2 The SSL fixation (SSLF) procedure has continued to be a mainstay in the surgical treatment of vaginal vault prolapse.3,4 Although modifications of this procedure have been described that advocate attachment of both posterior and anterior vaginal wall to the SSL, and bilateral vs unilateral suspension of the vaginal cuff,5-8 the recommended location for SSL suture placement remains the
From the Division of Urogynecology and Reconstructive Pelvic Surgery, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX. Presented at the 33rd Annual Scientific Meeting of the Society of Gynecologic Surgeons, Orlando, FL, April 12-14, 2007. Received Jan. 17, 2007; revised May 17, 2007; accepted Aug. 27, 2007. Reprints not available from the authors. 0002-9378/$32.00 © 2007 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2007.08.061
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same, approximately 2 finger breadths from the ischial spine.9,10 The SSL consists of dense connective tissue and contributes to the stability of the bony pelvis. It attaches to the ischial spine laterally and lower part of the sacrum and coccyx medially. The sacrospinous, along with the sacrotuberous ligament, divides the sciatic notches of the ischium into the lesser and greater sciatic foramen (GSF). The internal pudendal and inferior gluteal vessels, sciatic nerve, and other branches of the sacral nerve plexus pass through the GSF in close proximity to the ischial spines and SSL. On the superior or pelvic surface of the SSL lies the coccygeus muscle, which together with the levator ani muscles comprises the pelvic diaphragm. The coccygeus muscle has the same bony attachments and runs an identical course to the SSL; thus, many refer to these structures as the coccygeus–SSL (C-SSL) complex. Complications specifically associated with SSLF include hemorrhage (2-8%), and perineal, gluteal, or lower extremity pain (3-15%).5,9-12 These have inspired reconsideration and the evaluation of the pelvic anatomy in this region. However, most studies have focused on the
American Journal of Obstetrics & Gynecology DECEMBER 2007
vascular anatomy of the C-SSL complex in the region of the ischial spine and on pudendal nerve anatomy.12-16 Although the anatomic location of the internal pudendal vessels and pudendal nerve justifies the recommendation that sutures be placed 2 finger breadths medial from the ischial spine, other neurovascular structures and relationships in this region need closer examination. Specifically, studies that evaluate the neurovascular anatomy associated with the medial or sacral portion of C-SSL are scarce and limited by the small number of specimens examined.13-17 Therefore, the objective of this study was to further characterize the neurovascular anatomy of the C-SSL region and to correlate these findings to the SSLF procedure.
M ATERIALS AND M ETHODS The anatomy of the C-SSL complex region was examined in 13 unembalmed and 8 embalmed female cadavers. The cadavers were obtained from the Willed Body Program at the University of Texas Southwestern Medical Center in Dallas, TX. This study was considered exempt by the University of Texas Southwestern Medical Center Institutional Review
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www.AJOG.org Board in accordance with the Code of Federal Regulations, Title 45. Age, race, height, weight, and cause of death of the body donor at the time of death were available for all cadavers. Dissections were completed through the transabdominal (n ⫽ 21) and gluteal (n ⫽ 4) approaches. Distances of the pudendal nerve, internal pudendal artery, inferior gluteal artery, and sacral nerves were recorded in reference to the ischial spines and superior border of the C-SSL complex. The width of the vessels at their point of exit from the GSF was also documented. The nerves to the coccygeus and levator ani muscles were dissected and their relationship to the C-SSL complex was recorded. Distances were measured twice using the same caliper and a 10-cm plastic ruler with the pelvis in the supine position. Cadavers with evidence of previous reconstructive surgery at the time of dissection were excluded. Following entry into the abdominal cavity, the rectosigmoid was tied and transected, and the intestines proximal to this level removed. All cadavers were then cut transversely just above the aortic bifurcation and at the proximal thigh. The presacral space was entered bluntly and the fat and loose areolar tissue was removed to expose the medial aspect of the anterior sacral foramina. The peritoneum and loose areolar tissue surrounding the common and external iliac vessels were sharply removed. These and other pelvic sidewall vessels were retracted medially to expose the lumbosacral trunk as it crossed over the anterior surface of the ilium. The internal iliac artery was identified and its branches dissected. The internal pudendal and inferior gluteal arteries were followed to their point of exit from the GSF. The specimens were then transected in the midsagittal plane to aid with dissection of the GSF and C-SSL region. To facilitate dissection and examine the structures reported, removal of the internal iliac vein and many of its tributaries was necessary. This precluded accurate examination of the inferior gluteal veins. The connective tissue overlying the GSF and superior or pelvic aspect of the coccygeus and levator ani muscles
was carefully dissected to expose the CSSL complex and neurovascular structures. The medial aspect of the ischial spine was identified and marked by a colored pin. The length of the C-SSL complex was measured from the tip of the ischial spine to the lateral aspect of the fourth sacral foramen. The location of the nerves to the coccygeus and levator ani muscles in reference to the segment (lateral, mid, or medial) of the C-SSL complex on which they coursed was recorded. A gluteal dissection was completed in a subset (n ⫽ 4) of specimens to examine the course of the inferior gluteal and internal pudendal artery relative to the ischial spine and posterior surface of the C-SSL complex. A midline vertical incision was made along the posterior aspect of the midsacrum and coccyx. The gluteus maximus was exposed, detached from its attachments to the iliac crest and sacrum, and reflected laterally to reveal the gluteus medius. The gluteus medius was then reflected off to expose the sacrotuberous and sacrospinous ligament, pudendal neurovasculature, and inferior gluteal artery. Statistical analysis was performed using the SigmaStat 2.03 statistics software (Systat Software, Inc, San Jose, CA). Continuous variables were summarized by means, ranges, and SDs. Qualitative data were summarized by counts and percentages.
TABLE 1
Demographics of study population Demographic characteristic
Value
Total number cadavers, n
21
Age, mean ⫾ SD, y
80.9 ⫾ 15.0
........................................................................................................... ...........................................................................................................
Race, n (%)
..................................................................................................
White
21 (100)
...........................................................................................................
Body mass index, mean ⫾ SD, kg/m2
25.9 ⫾ 6.6
Reported cause of death, n (%)
21 (100)
...........................................................................................................
..................................................................................................
Neurologic
2 (10)
..................................................................................................
Cardiopulmonary
15 (71)
..................................................................................................
Cancer
3 (14)
Other
1 (5)
..................................................................................................
Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
Nerves to the coccygeus and levator ani muscles The innervation to the coccygeus and levator ani muscles was successfully examined in 36 of 42 pelvic halves. In 100% of these dissections, branches originating from S3, S4, S5, or a combination of these nerves were noted to perforate the pelvic surface of the coccygeus and levator ani. Branches to the coccygeus muscle arose from S3 and/or S4 in 94% (34 of FIGURE 1
Neurovascular anatomy
R ESULTS Study population characteristics A total of 21 cadaver specimens (8 embalmed and 13 unembalmed) were examined. None of the 21 cadavers had evidence of prior reconstructive pelvic surgery. Limited demographic characteristics of these cadavers are presented in Table 1.
C-SSL complex The average length of the right C-SSL complex was 53.7 mm (range, 44-60 mm) and that of the left C-SSL was 53.6 (range, 44-62) mm (Figure 1).
C-SSL, sacral nerve roots (S1-S4), and pudendal nerve (PN). Ischial spine (IS), midpoint of superior border of C-SSL (indicated by asterisk), IPA, and IGA. Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
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SGS Meeting Papers FIGURE 2
Coccygeus muscle innervation
www.AJOG.org (86%), a branch of S4 coursed medially and loosely attached to the lateral aspect of the rectum, prior to sending branches to the levator ani muscles (Figure 4).
FIGURE 4
Nerves to the pelvic floor muscles
Pudendal and sacral nerves
Lumbosacral trunk to third sacral nerve (LSTS3), nerve to the coccygeus (indicated by triple asterisks), and ischial spine (IS). Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
36) of pelvic halves. In the remaining 2 pelvic halves, innervation to the coccygeus was derived from S4 and S5. These nerves coursed obliquely from medial to lateral perforating the middle third of the coccygeus muscle in 89% (32 of 36) of specimens (Figure 2). In the remaining 4 pelvic halves (11%), the nerve(s) perforated the muscle in its medial third. Nerve branches that perforated the iliococcygeus muscles were identified in 36 of pelvic halves. In all of the dissections, S3 and/or S4 coursed over the midportion of the coccygeus and iliococcygeus and perforated the muscle at various sites (Figure 3). In 31 of 36 of dissections FIGURE 3
Nerve to the levator ani
Lumbosacral trunk to fourth sacral nerves (LSTS4), ischial spine (IS), nerve to iliococcygeus (indicated by asterisk), and pubic symphysis (PS). Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
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In all dissections, either the pudendal or third sacral nerve (S3) coursed parallel over the superior border of the C-SSL complex (Figure 1). In the majority (30 of 42) of pelvic halves, no measurable space between the superior border of CSSL and either S3 or pudendal nerve was noted at the midportion of the complex. However, in the remaining 29% (12 of 42) of the dissections, a freely exposed area above the C-SSL complex averaging 1.0 (range, 0.5-1.5) mm was present. In 100% of specimens, branches of S2 and S4 joined S3 at variable distances from the sacral foramina to form the pudendal nerve. The fourth sacral nerve (S4) was noted to course obliquely over the medial portion of the coccygeus muscle before joining S3 in forming the pudendal nerve (Figure 1).
Inferior gluteal artery The course of the IGA was successfully followed in all but 3 pelvic halves in which the IGA was severed during the dissection. In the remaining 39 pelvic halves, the IGA originated from the internal iliac and exited the pelvis through the GSF inferior to the piriformis muscle. From its origin, the IGA coursed laterally toward the superior border of the C-SSL complex and then exited the pelvis by passing in between sacral nerve roots (Figure 5). In the majority of dissections (92%), it passed between S2 and S3 (Table 2). In 10% of specimens, the inferior gluteal and internal pudendal artery arose from a common trunk that divided behind the ischial spine. The mean vertical distance from the IGA to the superior aspect of the C-SSL complex was 3.4 (range, 1-5) mm (Table 3). At its point of exit from the pelvis, the average distance of this vessel from the ischial spine was 24.2 (range, 15-36) mm. The mean width of the IGA at its exit point was 4.0 (range, 2-6) mm. In all gluteal dissections (n ⫽ 4), the IGA
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Third to fourth sacral nerves (S3-S4), coccygeus muscle (C), nerve to the coccygeus (indicated by double asterisks), and nerve to iliococcygeus (arrowheads). Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
coursed along the mid portion of the posterior aspect of the C-SSL complex.
Internal pudendal artery (PA) The course of the IPA was traced in 38 of the 42 pelvic halves examined (Figure 6). In the remaining 4 pelvic halves, the vessel was damaged during the dissection. The IPA arose from the anterior division FIGURE 5
Course and relationships of the IGA
Course and relationships of the IGA to the ischial spine (indicated by asterisk) and superior border of the C-SSL complex are shown. Lumbosacral trunk to third sacral nerve (LST-S3), pudendal nerve (PN), IPA, and pubic symphysis (PS) are also shown. Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
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TABLE 2
TABLE 3
Position of IGA relative to sacral nerves at its exit point
Width and relationships of IGA to ischial spine (IS) and superior border of C-SSL at its exit point
IGA exit point
Right Left hemipelvis, hemipelvis, n (%) n (%)
Between S2 and S3
20 (95)
Between S1and S2
1 (5)
16 (89)
...........................................................................................................
2 (11)
Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
of the internal iliac and exited the pelvis through the GSF inferior to the piriformis muscle. From its origin, the IPA coursed laterally toward the superior border of the C-SSL complex and the ischial spine. In 89% (34 of 38) of pelvic halves, the IPA coursed directly behind the ischial spine as it exited the GSF. In the remaining 4 pelvic halves, the artery was located within 1.5 mm from the spine. The average width of the IPA prior to exiting the pelvis was 2.3 mm. Gluteal dissections (n ⫽ 4) showed that the IPA continued its course behind the ischial spine and FIGURE 6
Course and relationships of the IPA
Course and relationships of the IPA to the ischial spine (IS) and superior border of the C-SSL complex are shown. Lumbosacral trunk to the fifth sacral nerve (LST-S5) and IGA are also shown. Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
IGA Hemipelvis (n)
Width (mean ⴞ SD, mm)
Distance from IS (mean ⴞ SD, mm)
Distance from C-SSL (mean ⴞ SD, mm)
Right (21)
4.0 ⫾ 0.7
23.8 ⫾ 5.6
3.3 ⫾ 1.3
Left (18)
4.1 ⫾ 0.7
24.6 ⫾ 5.8
3.6 ⫾ 1.4
Total (39)
4.0 ⫾ 0.7
24.2 ⫾ 5.7
3.4 ⫾ 1.4
.............................................................................................................................................................................................................................................. ..............................................................................................................................................................................................................................................
Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
then entered a split in the obturator internus fascia (pudendal canal) on the medial surface of the ischium.
C OMMENT Although the pudendal neurovasculature has traditionally received the most attention, injuries to the nerves that supply the coccygeus and levator ani muscles and to S4 are more likely to occur during SSLF. In this anatomic study of 21 female cadavers, innervation to the coccygeus and levator ani muscles arose individually or in combination from S3 to S5. In the majority of dissections (89%), branches to the coccygeus and/or levator ani muscles coursed over the midportion of the C-SSL complex, just in the area where SSLF sutures are placed. These findings are consistent with observations reported by Barber et al,17 who showed that innervation to the levator ani muscle arose from S3 to S5 in 10 female cadavers and that these nerves coursed over midportion of the muscles. Therefore, even when SSLF sutures are placed as recommended, these are the structures most likely to be injured or entrapped. Some of the reported postoperative complications of SSLF, such as dyspareunia and pelvic pain are typically attributed to the nonanatomic posterior and lateral deflection of the vaginal axis. However, given the findings of this study, it is certainly possible that injury to the nerves that supply the coccygeus and levator ani muscles may lead to unrecognized muscle spasm or dysfunction. It is also possible that denervation injury of the levator ani muscles may increase the risk of prolapse recurrence.
To objectively evaluate the role of nerve injury in pelvic floor dysfunction would require pre- and postneurophysiologic studies or indirect assessment of muscle function with magnetic resonance imaging. In general, identification of the nerves to the coccygeus and levator ani muscles required meticulous dissection from overlying loose connective tissue; therefore, it is unlikely these structures could be easily visualized intraoperatively. One method to decrease entrapment of these nerves would be to perforate the ligament in a vertical rather than a horizontal orientation in attempts to follow the course of the nerves. Additionally, these nerves were not observed to course in the lateral third segment of the C-SSL, and therefore, placement of the SSLF sutures within this region may decrease the risk of nerve injury. The pudendal nerve was formed from S2 to S4 and coursed parallel to the superior border of the C-SSL complex in all specimens. In all dissections, S4 obliquely traversed the pelvic surface of the coccygeus muscle to join S3 in forming the pudendal nerve. Thus, placement of sutures closer to the sacral attachment of the ligament can lead to entrapment or laceration of S4 and cause similar symptoms as those caused by injury to the pudendal nerve. Because the pudendal nerve provides the bulk of the sensory and motor innervation to the perineum and the striated urethral and anal sphincters, injury to this nerve may explain some of the pain symptoms and other pelvic floor dysfunctions that have been reported following SSLF procedures.4,5,7,10,11 In-
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SGS Meeting Papers deed, Welgoss et al18 reported new-onset post-SSLF neuropathy by using preoperative and postoperative perineal nerve terminal motor latency tests. To avoid direct injury to the pudendal nerve, it is important that the exit point of the needle not be above the superior border of the C-SSL complex. Sutures placed in the medial segment of the C-SSL may lead to entrapment and injury to S4. This may occur unintentionally with shorter than average C-SSL or if the combined width of the surgeon’s middle and index fingers exceeds 2.5 cm. Findings in this study confirm that SSLF sutures placed 2 finger breadths medial to the ischial spine are in closer proximity to the inferior gluteal artery than to the internal pudendal artery. As previously reported, the IPA coursed behind or in very close proximity to the ischial spine in all dissections.12,13 The IGA was found, on average, 2.4 cm from the ischial spine, precisely the region in which SSLF sutures are placed. These findings were consistent with those found by Barksdale et al.12 However, in the majority of dissections, the IGA coursed posterior to S3 or the pudendal nerve. Because these nerves traveled adjacent to the superior border of the CSSL complex, injury to the IGA is not likely to occur unless the needle exits above the upper margin of the C-SSL complex. The findings of our study also suggest that this risk would be greatest in the 29% of cases in whom the IGA was found exposed in a small window above the CSSL complex. Thomspon et al13 drew similar conclusions based on their observations where the IGA was exposed in a 3-5 mm window above the C-SSL. The relative contribution of arterial vs venous bleeding during SSLF is not known. However, given the extensive and unpredictable course of the pelvic veins, it is more likely that intraoperative hemorrhage is of venous origin. Injury to the inferior gluteal vein or to the venous plexus that drain the pelvic viscera can result from either retractor positioning or needle puncture. Although venous bleeding may be more difficult to control, this low-pressure system allows for 660.e5
www.AJOG.org coagulation to occur with sustained pressure. Because of the deep location and somewhat limited accessibility of the SSL region, packing and sustained pressure is the initial measure recommended in managing this complication, especially when hemorrhage is suspected to be of venous origin. If packing alone is unsuccessful, and arterial bleeding is suspected, clipping or ligation of the vessel under direct visualization may be achieved immediately after removing the pack. In a stable patient who has persistent arterial bleeding, interventional radiology consultation for possible embolization is an option. Internal iliac artery ligation has not been generally advocated for hemorrhage encountered during SSLF given the extensive collateral circulation between the inferior gluteal, superior gluteal, and circumflex iliac arteries.10,12,13 One of the limitations of this study is that inherent to any gross dissection of fine structures deep in the pelvis. The nerves to the coccygeus and levator ani muscles were embedded in a web of connective tissue requiring meticulous and time consuming dissections. Although we did not confirm gross findings with histology, only nerves that directly arose from sacral nerves and were traced with certainty to their destinations were documented. It is conceivable that many of the smaller nerves that arose from the pudendal nerve or sacral plexus that coursed along blood vessels and embedded in connective tissue were destroyed during the dissection. However, this would only underestimate the extensive innervation to the pelvic floor. Another limitation is that all the cadavers in this study were white. Different lengths of the SSL and other neurovascular variations may be observed in women of different race. Despite these limitations, to our knowledge, this is the largest series that comprehensively examines the neural and arterial vascular anatomy of the SSL region in female cadavers with implications for SSLF. Based on this study, placement of SSLF sutures in the lateral third segment of the C-SSL or closer to the ischial spine than is generally recom-
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mended should result in fewer neurovascular complications. Knowledge of this anatomy is also critical as newer vaginal “kits” involving blind passage of trocars through the C-SSL complex are increasingly being utilized. f REFERENCES 1. Richter K. Die chirurgiesche anatomie dervagiaefixatio sacrospinalis vaginalis: ein beitrag zur operativen behandlung des scheidenblindsasch prolapses. Geburtshilfe Fauenheilkd 1968;28:321-7. 2. Randall CL, Nichols DH. Surgical treatment of vaginal inversion. Obstet Gynecol 1971; 38:327-32. 3. Nichols DH. Sacrospinous fixation for massive eversion of the vagina. Am J Obstet Gynecol 1982;142:901-4. 4. Morley GW, Delancey JO. Sacrospinous ligament fixation for eversion of the vagina with cystocele. Am J Obstet Gynecol 1988;158:872-81. 5. Sze EH, Karram MM. Transvaginal repair of vault prolapse: a review. Obstet Gynecol 1997;89:466-75. 6. Kearney R., DeLancey JO. Selecting suspension points and excising the vagina during the Michigan 4-wall sacrospinous suspension. Obstet Gynecol 2003;101:325-30. 7. Goldberg RP, Tomezsko JE, Winkler HA, Koduri S, Culligan PJ, Sand PK. Anterior or posterior vaginal vault suspension: long-term anatomic and functional evaluation. Obstet Gynecol 2001;98:199-204. 8. Nichols DH. Massive eversion of the vagina. In: Nichols DH, ed. Gynecologic and obstetric surgery. St. Louis: Mosby; 1993. p. 431-64. 9. Karram MM, Kleeman SD. Vaginal vault prolapse. In: Rock JA, Jones HW 3rd, ed. TeLinde’s operative gynecology. 9th ed. Philadelphia: Lippincott Williams & Wilkins; 2003. p. 999-1032. 10. Walters MD, Karram MM. Surgical treatment of vaginal vault prolapse and enterocele. In: Walters MD, Karram MM, eds. Urogynecology and reconstructive pelvic surgery. 3rd ed. Philadelphia: Mosby; 2007. p. 262-87. 11. Paraiso MF, Ballard LA, Walters MD, Lee JC, Mitchinson AR. Pelvic support defects and visceral and sexual function in women treated with sacrospinous ligament suspension and pelvic reconstruction. Am J Obstet Gynecol 1996;175:1423-31. 12. Barksdale PA, Elkins TE, Sanders CK, Jaramillo FE, Gasser RF. An anatomic approach to pelvic hemorrhage during sacrospinous ligament fixation of the vaginal vault. Obstet Gynecol 1998;91:715-8. 13. Thompson JR, Gibb JS, Genadry R, Burrows L, Lambrou N, Buller JL. Anatomy of pelvic arteries adjacent to the sacrospinous ligament: importance of the coccygeal branch of the inferior gluteal artery. Obstet Gynecol 1999;94:973-7. 14. Barksdale PA, Gasser RF, Gauthier CM, Elkins TE, Wall LL. Intraligamentous nerves as a potential source of pain after sacrospinous lig-
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www.AJOG.org ament fixation of the vaginal apex. Int Urogynecol J 1997;8:121-5. 15. Mahakkanukrauh P, Surin P, Vaidhayakarn P. Anatomical study of the pudendal nerve adjacent to the sacrospinous ligament. Clin Anat 2005;18:200-5.
16. Wallner C, Maas CP, Dabhoiwala NF, Wouter LH, DeRuiter MC. Innervation of the pelvic floor muscles: a reappraisal for the levator ani nerve. Obstet Gynecol 2006;108:529-34. 17. Barber MD, Bremer RE, Thor KB, Dolber PC, Kuehl TJ, Coates KW. Innervation of the
female levator ani muscles. Am J Obstet Gynecol 2002;187:64-71. 18. Welgoss JA, Vogt VY, McClellan EJ, Benson JT. Relationship between surgically induced neuropathy and outcome of pelvic organ prolapse surgery. Int Urogynecol J 1990;10:11-4.
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Neurovascular anatomy of the sacrospinous ligament region in female cadavers: Implications in sacrospinous ligament fixation Shayzreen M. Roshanravan, MD; Cecilia K. Wieslander, MD; Joseph I. Schaffer, MD; Marlene M. Corton, MD OBJECTIVE: The objective of the study was to further characterize the anatomy of the coccygeus muscle–sacrospinous ligament (C-SSL) complex and to correlate the findings with sacrospinous ligament fixations (SSLF). STUDY DESIGN: Dissections were performed in 21 female cadavers. RESULTS: In all dissections, nerves originating from S3, S4, S5, or a
combination passed over the anterior surface of the C-SSL at its midsegment, and either the pudendal or third sacral nerve coursed on the superior border of C-SSL at its midpoint. In 100% of specimens, the internal pudendal artery (IPA) passed behind or just medial to the is-
chial spine. The average distance of the inferior gluteal artery (IGA) from the ischial spine and the superior border of the C-SSL was 24.2 (range, 15-35) mm and 3.4 (range, 1-5) mm, respectively. CONCLUSION: Nerves to the coccygeus and levator ani coursed over the midportion of the C-SSL where SSLF sutures are placed. The pudendal nerve and IGA were in proximity to the superior border of the C-SSL at its midportion, whereas the IPA passed behind the ischial spine, lateral to the recommended site for suture placement.
Key words: inferior gluteal artery, nerve to coccygeus, nerve to levator ani, pudendal nerve, sacrospinous ligament
Cite this article as: Roshanravan SM, Wieslander CK, Schaffer JI, et al. Neurovascular anatomy of the sacrospinous ligament region in female cadavers: Implications in sacrospinous ligament fixation. Am J Obstet Gynecol 2007;197:660.e1-660.e6.
F
ixation of the vaginal vault to the sacrospinous ligament (SSL) was initially described by Richter in 19681 and introduced in the United States by Randall and Nichols in 1971.2 The SSL fixation (SSLF) procedure has continued to be a mainstay in the surgical treatment of vaginal vault prolapse.3,4 Although modifications of this procedure have been described that advocate attachment of both posterior and anterior vaginal wall to the SSL, and bilateral vs unilateral suspension of the vaginal cuff,5-8 the recommended location for SSL suture placement remains the
From the Division of Urogynecology and Reconstructive Pelvic Surgery, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX. Presented at the 33rd Annual Scientific Meeting of the Society of Gynecologic Surgeons, Orlando, FL, April 12-14, 2007. Received Jan. 17, 2007; revised May 17, 2007; accepted Aug. 27, 2007. Reprints not available from the authors. 0002-9378/$32.00 © 2007 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2007.08.061
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same, approximately 2 finger breadths from the ischial spine.9,10 The SSL consists of dense connective tissue and contributes to the stability of the bony pelvis. It attaches to the ischial spine laterally and lower part of the sacrum and coccyx medially. The sacrospinous, along with the sacrotuberous ligament, divides the sciatic notches of the ischium into the lesser and greater sciatic foramen (GSF). The internal pudendal and inferior gluteal vessels, sciatic nerve, and other branches of the sacral nerve plexus pass through the GSF in close proximity to the ischial spines and SSL. On the superior or pelvic surface of the SSL lies the coccygeus muscle, which together with the levator ani muscles comprises the pelvic diaphragm. The coccygeus muscle has the same bony attachments and runs an identical course to the SSL; thus, many refer to these structures as the coccygeus–SSL (C-SSL) complex. Complications specifically associated with SSLF include hemorrhage (2-8%), and perineal, gluteal, or lower extremity pain (3-15%).5,9-12 These have inspired reconsideration and the evaluation of the pelvic anatomy in this region. However, most studies have focused on the
American Journal of Obstetrics & Gynecology DECEMBER 2007
vascular anatomy of the C-SSL complex in the region of the ischial spine and on pudendal nerve anatomy.12-16 Although the anatomic location of the internal pudendal vessels and pudendal nerve justifies the recommendation that sutures be placed 2 finger breadths medial from the ischial spine, other neurovascular structures and relationships in this region need closer examination. Specifically, studies that evaluate the neurovascular anatomy associated with the medial or sacral portion of C-SSL are scarce and limited by the small number of specimens examined.13-17 Therefore, the objective of this study was to further characterize the neurovascular anatomy of the C-SSL region and to correlate these findings to the SSLF procedure.
M ATERIALS AND M ETHODS The anatomy of the C-SSL complex region was examined in 13 unembalmed and 8 embalmed female cadavers. The cadavers were obtained from the Willed Body Program at the University of Texas Southwestern Medical Center in Dallas, TX. This study was considered exempt by the University of Texas Southwestern Medical Center Institutional Review
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www.AJOG.org Board in accordance with the Code of Federal Regulations, Title 45. Age, race, height, weight, and cause of death of the body donor at the time of death were available for all cadavers. Dissections were completed through the transabdominal (n ⫽ 21) and gluteal (n ⫽ 4) approaches. Distances of the pudendal nerve, internal pudendal artery, inferior gluteal artery, and sacral nerves were recorded in reference to the ischial spines and superior border of the C-SSL complex. The width of the vessels at their point of exit from the GSF was also documented. The nerves to the coccygeus and levator ani muscles were dissected and their relationship to the C-SSL complex was recorded. Distances were measured twice using the same caliper and a 10-cm plastic ruler with the pelvis in the supine position. Cadavers with evidence of previous reconstructive surgery at the time of dissection were excluded. Following entry into the abdominal cavity, the rectosigmoid was tied and transected, and the intestines proximal to this level removed. All cadavers were then cut transversely just above the aortic bifurcation and at the proximal thigh. The presacral space was entered bluntly and the fat and loose areolar tissue was removed to expose the medial aspect of the anterior sacral foramina. The peritoneum and loose areolar tissue surrounding the common and external iliac vessels were sharply removed. These and other pelvic sidewall vessels were retracted medially to expose the lumbosacral trunk as it crossed over the anterior surface of the ilium. The internal iliac artery was identified and its branches dissected. The internal pudendal and inferior gluteal arteries were followed to their point of exit from the GSF. The specimens were then transected in the midsagittal plane to aid with dissection of the GSF and C-SSL region. To facilitate dissection and examine the structures reported, removal of the internal iliac vein and many of its tributaries was necessary. This precluded accurate examination of the inferior gluteal veins. The connective tissue overlying the GSF and superior or pelvic aspect of the coccygeus and levator ani muscles
was carefully dissected to expose the CSSL complex and neurovascular structures. The medial aspect of the ischial spine was identified and marked by a colored pin. The length of the C-SSL complex was measured from the tip of the ischial spine to the lateral aspect of the fourth sacral foramen. The location of the nerves to the coccygeus and levator ani muscles in reference to the segment (lateral, mid, or medial) of the C-SSL complex on which they coursed was recorded. A gluteal dissection was completed in a subset (n ⫽ 4) of specimens to examine the course of the inferior gluteal and internal pudendal artery relative to the ischial spine and posterior surface of the C-SSL complex. A midline vertical incision was made along the posterior aspect of the midsacrum and coccyx. The gluteus maximus was exposed, detached from its attachments to the iliac crest and sacrum, and reflected laterally to reveal the gluteus medius. The gluteus medius was then reflected off to expose the sacrotuberous and sacrospinous ligament, pudendal neurovasculature, and inferior gluteal artery. Statistical analysis was performed using the SigmaStat 2.03 statistics software (Systat Software, Inc, San Jose, CA). Continuous variables were summarized by means, ranges, and SDs. Qualitative data were summarized by counts and percentages.
TABLE 1
Demographics of study population Demographic characteristic
Value
Total number cadavers, n
21
Age, mean ⫾ SD, y
80.9 ⫾ 15.0
........................................................................................................... ...........................................................................................................
Race, n (%)
..................................................................................................
White
21 (100)
...........................................................................................................
Body mass index, mean ⫾ SD, kg/m2
25.9 ⫾ 6.6
Reported cause of death, n (%)
21 (100)
...........................................................................................................
..................................................................................................
Neurologic
2 (10)
..................................................................................................
Cardiopulmonary
15 (71)
..................................................................................................
Cancer
3 (14)
Other
1 (5)
..................................................................................................
Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
Nerves to the coccygeus and levator ani muscles The innervation to the coccygeus and levator ani muscles was successfully examined in 36 of 42 pelvic halves. In 100% of these dissections, branches originating from S3, S4, S5, or a combination of these nerves were noted to perforate the pelvic surface of the coccygeus and levator ani. Branches to the coccygeus muscle arose from S3 and/or S4 in 94% (34 of FIGURE 1
Neurovascular anatomy
R ESULTS Study population characteristics A total of 21 cadaver specimens (8 embalmed and 13 unembalmed) were examined. None of the 21 cadavers had evidence of prior reconstructive pelvic surgery. Limited demographic characteristics of these cadavers are presented in Table 1.
C-SSL complex The average length of the right C-SSL complex was 53.7 mm (range, 44-60 mm) and that of the left C-SSL was 53.6 (range, 44-62) mm (Figure 1).
C-SSL, sacral nerve roots (S1-S4), and pudendal nerve (PN). Ischial spine (IS), midpoint of superior border of C-SSL (indicated by asterisk), IPA, and IGA. Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
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Coccygeus muscle innervation
www.AJOG.org (86%), a branch of S4 coursed medially and loosely attached to the lateral aspect of the rectum, prior to sending branches to the levator ani muscles (Figure 4).
FIGURE 4
Nerves to the pelvic floor muscles
Pudendal and sacral nerves
Lumbosacral trunk to third sacral nerve (LSTS3), nerve to the coccygeus (indicated by triple asterisks), and ischial spine (IS). Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
36) of pelvic halves. In the remaining 2 pelvic halves, innervation to the coccygeus was derived from S4 and S5. These nerves coursed obliquely from medial to lateral perforating the middle third of the coccygeus muscle in 89% (32 of 36) of specimens (Figure 2). In the remaining 4 pelvic halves (11%), the nerve(s) perforated the muscle in its medial third. Nerve branches that perforated the iliococcygeus muscles were identified in 36 of pelvic halves. In all of the dissections, S3 and/or S4 coursed over the midportion of the coccygeus and iliococcygeus and perforated the muscle at various sites (Figure 3). In 31 of 36 of dissections FIGURE 3
Nerve to the levator ani
Lumbosacral trunk to fourth sacral nerves (LSTS4), ischial spine (IS), nerve to iliococcygeus (indicated by asterisk), and pubic symphysis (PS). Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
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In all dissections, either the pudendal or third sacral nerve (S3) coursed parallel over the superior border of the C-SSL complex (Figure 1). In the majority (30 of 42) of pelvic halves, no measurable space between the superior border of CSSL and either S3 or pudendal nerve was noted at the midportion of the complex. However, in the remaining 29% (12 of 42) of the dissections, a freely exposed area above the C-SSL complex averaging 1.0 (range, 0.5-1.5) mm was present. In 100% of specimens, branches of S2 and S4 joined S3 at variable distances from the sacral foramina to form the pudendal nerve. The fourth sacral nerve (S4) was noted to course obliquely over the medial portion of the coccygeus muscle before joining S3 in forming the pudendal nerve (Figure 1).
Inferior gluteal artery The course of the IGA was successfully followed in all but 3 pelvic halves in which the IGA was severed during the dissection. In the remaining 39 pelvic halves, the IGA originated from the internal iliac and exited the pelvis through the GSF inferior to the piriformis muscle. From its origin, the IGA coursed laterally toward the superior border of the C-SSL complex and then exited the pelvis by passing in between sacral nerve roots (Figure 5). In the majority of dissections (92%), it passed between S2 and S3 (Table 2). In 10% of specimens, the inferior gluteal and internal pudendal artery arose from a common trunk that divided behind the ischial spine. The mean vertical distance from the IGA to the superior aspect of the C-SSL complex was 3.4 (range, 1-5) mm (Table 3). At its point of exit from the pelvis, the average distance of this vessel from the ischial spine was 24.2 (range, 15-36) mm. The mean width of the IGA at its exit point was 4.0 (range, 2-6) mm. In all gluteal dissections (n ⫽ 4), the IGA
American Journal of Obstetrics & Gynecology DECEMBER 2007
Third to fourth sacral nerves (S3-S4), coccygeus muscle (C), nerve to the coccygeus (indicated by double asterisks), and nerve to iliococcygeus (arrowheads). Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
coursed along the mid portion of the posterior aspect of the C-SSL complex.
Internal pudendal artery (PA) The course of the IPA was traced in 38 of the 42 pelvic halves examined (Figure 6). In the remaining 4 pelvic halves, the vessel was damaged during the dissection. The IPA arose from the anterior division FIGURE 5
Course and relationships of the IGA
Course and relationships of the IGA to the ischial spine (indicated by asterisk) and superior border of the C-SSL complex are shown. Lumbosacral trunk to third sacral nerve (LST-S3), pudendal nerve (PN), IPA, and pubic symphysis (PS) are also shown. Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
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TABLE 2
TABLE 3
Position of IGA relative to sacral nerves at its exit point
Width and relationships of IGA to ischial spine (IS) and superior border of C-SSL at its exit point
IGA exit point
Right Left hemipelvis, hemipelvis, n (%) n (%)
Between S2 and S3
20 (95)
Between S1and S2
1 (5)
16 (89)
...........................................................................................................
2 (11)
Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
of the internal iliac and exited the pelvis through the GSF inferior to the piriformis muscle. From its origin, the IPA coursed laterally toward the superior border of the C-SSL complex and the ischial spine. In 89% (34 of 38) of pelvic halves, the IPA coursed directly behind the ischial spine as it exited the GSF. In the remaining 4 pelvic halves, the artery was located within 1.5 mm from the spine. The average width of the IPA prior to exiting the pelvis was 2.3 mm. Gluteal dissections (n ⫽ 4) showed that the IPA continued its course behind the ischial spine and FIGURE 6
Course and relationships of the IPA
Course and relationships of the IPA to the ischial spine (IS) and superior border of the C-SSL complex are shown. Lumbosacral trunk to the fifth sacral nerve (LST-S5) and IGA are also shown. Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
IGA Hemipelvis (n)
Width (mean ⴞ SD, mm)
Distance from IS (mean ⴞ SD, mm)
Distance from C-SSL (mean ⴞ SD, mm)
Right (21)
4.0 ⫾ 0.7
23.8 ⫾ 5.6
3.3 ⫾ 1.3
Left (18)
4.1 ⫾ 0.7
24.6 ⫾ 5.8
3.6 ⫾ 1.4
Total (39)
4.0 ⫾ 0.7
24.2 ⫾ 5.7
3.4 ⫾ 1.4
.............................................................................................................................................................................................................................................. ..............................................................................................................................................................................................................................................
Roshanravan. Neurovascular anatomy of the sacrospinous ligament region in female cadavers. Am J Obstet Gynecol 2007.
then entered a split in the obturator internus fascia (pudendal canal) on the medial surface of the ischium.
C OMMENT Although the pudendal neurovasculature has traditionally received the most attention, injuries to the nerves that supply the coccygeus and levator ani muscles and to S4 are more likely to occur during SSLF. In this anatomic study of 21 female cadavers, innervation to the coccygeus and levator ani muscles arose individually or in combination from S3 to S5. In the majority of dissections (89%), branches to the coccygeus and/or levator ani muscles coursed over the midportion of the C-SSL complex, just in the area where SSLF sutures are placed. These findings are consistent with observations reported by Barber et al,17 who showed that innervation to the levator ani muscle arose from S3 to S5 in 10 female cadavers and that these nerves coursed over midportion of the muscles. Therefore, even when SSLF sutures are placed as recommended, these are the structures most likely to be injured or entrapped. Some of the reported postoperative complications of SSLF, such as dyspareunia and pelvic pain are typically attributed to the nonanatomic posterior and lateral deflection of the vaginal axis. However, given the findings of this study, it is certainly possible that injury to the nerves that supply the coccygeus and levator ani muscles may lead to unrecognized muscle spasm or dysfunction. It is also possible that denervation injury of the levator ani muscles may increase the risk of prolapse recurrence.
To objectively evaluate the role of nerve injury in pelvic floor dysfunction would require pre- and postneurophysiologic studies or indirect assessment of muscle function with magnetic resonance imaging. In general, identification of the nerves to the coccygeus and levator ani muscles required meticulous dissection from overlying loose connective tissue; therefore, it is unlikely these structures could be easily visualized intraoperatively. One method to decrease entrapment of these nerves would be to perforate the ligament in a vertical rather than a horizontal orientation in attempts to follow the course of the nerves. Additionally, these nerves were not observed to course in the lateral third segment of the C-SSL, and therefore, placement of the SSLF sutures within this region may decrease the risk of nerve injury. The pudendal nerve was formed from S2 to S4 and coursed parallel to the superior border of the C-SSL complex in all specimens. In all dissections, S4 obliquely traversed the pelvic surface of the coccygeus muscle to join S3 in forming the pudendal nerve. Thus, placement of sutures closer to the sacral attachment of the ligament can lead to entrapment or laceration of S4 and cause similar symptoms as those caused by injury to the pudendal nerve. Because the pudendal nerve provides the bulk of the sensory and motor innervation to the perineum and the striated urethral and anal sphincters, injury to this nerve may explain some of the pain symptoms and other pelvic floor dysfunctions that have been reported following SSLF procedures.4,5,7,10,11 In-
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SGS Meeting Papers deed, Welgoss et al18 reported new-onset post-SSLF neuropathy by using preoperative and postoperative perineal nerve terminal motor latency tests. To avoid direct injury to the pudendal nerve, it is important that the exit point of the needle not be above the superior border of the C-SSL complex. Sutures placed in the medial segment of the C-SSL may lead to entrapment and injury to S4. This may occur unintentionally with shorter than average C-SSL or if the combined width of the surgeon’s middle and index fingers exceeds 2.5 cm. Findings in this study confirm that SSLF sutures placed 2 finger breadths medial to the ischial spine are in closer proximity to the inferior gluteal artery than to the internal pudendal artery. As previously reported, the IPA coursed behind or in very close proximity to the ischial spine in all dissections.12,13 The IGA was found, on average, 2.4 cm from the ischial spine, precisely the region in which SSLF sutures are placed. These findings were consistent with those found by Barksdale et al.12 However, in the majority of dissections, the IGA coursed posterior to S3 or the pudendal nerve. Because these nerves traveled adjacent to the superior border of the CSSL complex, injury to the IGA is not likely to occur unless the needle exits above the upper margin of the C-SSL complex. The findings of our study also suggest that this risk would be greatest in the 29% of cases in whom the IGA was found exposed in a small window above the CSSL complex. Thomspon et al13 drew similar conclusions based on their observations where the IGA was exposed in a 3-5 mm window above the C-SSL. The relative contribution of arterial vs venous bleeding during SSLF is not known. However, given the extensive and unpredictable course of the pelvic veins, it is more likely that intraoperative hemorrhage is of venous origin. Injury to the inferior gluteal vein or to the venous plexus that drain the pelvic viscera can result from either retractor positioning or needle puncture. Although venous bleeding may be more difficult to control, this low-pressure system allows for 660.e5
www.AJOG.org coagulation to occur with sustained pressure. Because of the deep location and somewhat limited accessibility of the SSL region, packing and sustained pressure is the initial measure recommended in managing this complication, especially when hemorrhage is suspected to be of venous origin. If packing alone is unsuccessful, and arterial bleeding is suspected, clipping or ligation of the vessel under direct visualization may be achieved immediately after removing the pack. In a stable patient who has persistent arterial bleeding, interventional radiology consultation for possible embolization is an option. Internal iliac artery ligation has not been generally advocated for hemorrhage encountered during SSLF given the extensive collateral circulation between the inferior gluteal, superior gluteal, and circumflex iliac arteries.10,12,13 One of the limitations of this study is that inherent to any gross dissection of fine structures deep in the pelvis. The nerves to the coccygeus and levator ani muscles were embedded in a web of connective tissue requiring meticulous and time consuming dissections. Although we did not confirm gross findings with histology, only nerves that directly arose from sacral nerves and were traced with certainty to their destinations were documented. It is conceivable that many of the smaller nerves that arose from the pudendal nerve or sacral plexus that coursed along blood vessels and embedded in connective tissue were destroyed during the dissection. However, this would only underestimate the extensive innervation to the pelvic floor. Another limitation is that all the cadavers in this study were white. Different lengths of the SSL and other neurovascular variations may be observed in women of different race. Despite these limitations, to our knowledge, this is the largest series that comprehensively examines the neural and arterial vascular anatomy of the SSL region in female cadavers with implications for SSLF. Based on this study, placement of SSLF sutures in the lateral third segment of the C-SSL or closer to the ischial spine than is generally recom-
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mended should result in fewer neurovascular complications. Knowledge of this anatomy is also critical as newer vaginal “kits” involving blind passage of trocars through the C-SSL complex are increasingly being utilized. f REFERENCES 1. Richter K. Die chirurgiesche anatomie dervagiaefixatio sacrospinalis vaginalis: ein beitrag zur operativen behandlung des scheidenblindsasch prolapses. Geburtshilfe Fauenheilkd 1968;28:321-7. 2. Randall CL, Nichols DH. Surgical treatment of vaginal inversion. Obstet Gynecol 1971; 38:327-32. 3. Nichols DH. Sacrospinous fixation for massive eversion of the vagina. Am J Obstet Gynecol 1982;142:901-4. 4. Morley GW, Delancey JO. Sacrospinous ligament fixation for eversion of the vagina with cystocele. Am J Obstet Gynecol 1988;158:872-81. 5. Sze EH, Karram MM. Transvaginal repair of vault prolapse: a review. Obstet Gynecol 1997;89:466-75. 6. Kearney R., DeLancey JO. Selecting suspension points and excising the vagina during the Michigan 4-wall sacrospinous suspension. Obstet Gynecol 2003;101:325-30. 7. Goldberg RP, Tomezsko JE, Winkler HA, Koduri S, Culligan PJ, Sand PK. Anterior or posterior vaginal vault suspension: long-term anatomic and functional evaluation. Obstet Gynecol 2001;98:199-204. 8. Nichols DH. Massive eversion of the vagina. In: Nichols DH, ed. Gynecologic and obstetric surgery. St. Louis: Mosby; 1993. p. 431-64. 9. Karram MM, Kleeman SD. Vaginal vault prolapse. In: Rock JA, Jones HW 3rd, ed. TeLinde’s operative gynecology. 9th ed. Philadelphia: Lippincott Williams & Wilkins; 2003. p. 999-1032. 10. Walters MD, Karram MM. Surgical treatment of vaginal vault prolapse and enterocele. In: Walters MD, Karram MM, eds. Urogynecology and reconstructive pelvic surgery. 3rd ed. Philadelphia: Mosby; 2007. p. 262-87. 11. Paraiso MF, Ballard LA, Walters MD, Lee JC, Mitchinson AR. Pelvic support defects and visceral and sexual function in women treated with sacrospinous ligament suspension and pelvic reconstruction. Am J Obstet Gynecol 1996;175:1423-31. 12. Barksdale PA, Elkins TE, Sanders CK, Jaramillo FE, Gasser RF. An anatomic approach to pelvic hemorrhage during sacrospinous ligament fixation of the vaginal vault. Obstet Gynecol 1998;91:715-8. 13. Thompson JR, Gibb JS, Genadry R, Burrows L, Lambrou N, Buller JL. Anatomy of pelvic arteries adjacent to the sacrospinous ligament: importance of the coccygeal branch of the inferior gluteal artery. Obstet Gynecol 1999;94:973-7. 14. Barksdale PA, Gasser RF, Gauthier CM, Elkins TE, Wall LL. Intraligamentous nerves as a potential source of pain after sacrospinous lig-
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www.AJOG.org ament fixation of the vaginal apex. Int Urogynecol J 1997;8:121-5. 15. Mahakkanukrauh P, Surin P, Vaidhayakarn P. Anatomical study of the pudendal nerve adjacent to the sacrospinous ligament. Clin Anat 2005;18:200-5.
16. Wallner C, Maas CP, Dabhoiwala NF, Wouter LH, DeRuiter MC. Innervation of the pelvic floor muscles: a reappraisal for the levator ani nerve. Obstet Gynecol 2006;108:529-34. 17. Barber MD, Bremer RE, Thor KB, Dolber PC, Kuehl TJ, Coates KW. Innervation of the
female levator ani muscles. Am J Obstet Gynecol 2002;187:64-71. 18. Welgoss JA, Vogt VY, McClellan EJ, Benson JT. Relationship between surgically induced neuropathy and outcome of pelvic organ prolapse surgery. Int Urogynecol J 1990;10:11-4.
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