The American College of Obstetricians and Gynecologists recommends the vaginal approach as the preferred route for hysterectomy when feasible.1 Despite compelling evidence in favor of the vaginal approach, there is a continued national decline in vaginal hysterectomy numbers2 with only 13% of hysterectomies performed vaginally in teaching hospitals.3 Because of concerns about appropriate training, the Accreditation Council for Graduate Medical Education implemented a new system in 2012 establishing a minimum threshold of 15 vaginal hysterectomy procedures per graduating resident, highlighting the need to maximize trainee experience and improve vaginal surgical education.
Anterior colpotomy is one of the most difficult procedural steps to master during vaginal hysterectomy and may be a major obstacle to more widespread use of the vaginal approach. Fear of bleeding and cystotomy, or bladder entry, combined with surgeon inexperience and poor familiarity with surgical planes may heighten apprehension with this dissection.4,5 Thus, precise knowledge of surgical anatomy is crucial for safe and proficient performance of this important step.
Anatomically, the initial anterior incision is made through the full-thickness vaginal wall into the vesicovaginal space. The supravaginal septum is then encountered, consisting of augmented bands of connective tissue that separate the vesicovaginal and vesicocervical spaces and attach the lower pole of the bladder to the anterior cervix.6 Once the vesicocervical space is entered, the anterior peritoneum can be identified (Video, available online at http://links.lww.com/AOG/A863). The objective of this study was to quantify the distance of the dissection plane from the cervicovaginal junction to the anterior peritoneal reflection.
MATERIALS AND METHODS
The institutional review board at the University of Texas Southwestern Medical Center approved this descriptive study in accordance with the Code of Federal Regulations, title 45, part 46. The vesicocervical space and supravaginal septum were examined prospectively over a 2-year period from February 2011 to February 2013 in patients undergoing vaginal hysterectomy. Both general gynecology and female pelvic medicine and reconstructive surgery cases were identified using operating room schedules and preoperative clinic lists. Women older than 18 years of age undergoing vaginal hysterectomy were eligible for recruitment. Exclusion criteria included known gynecologic malignancy, prior cesarean delivery, any previous surgery affecting this area, and radiographic or clinically detected lesions such as leiomyomas causing significant anatomic distortion. The study population was a convenience sample of faculty patients undergoing vaginal hysterectomy. Verbal consent was obtained from all patients, and the institutional review board determined that written consent was not necessary.
Intraoperatively, the initial incision was made circumferentially at the cervicovaginal junction, where decreased rugae or a transverse fold mark the transition between the mobile vaginal wall and the smooth cervical stroma.7 After surgical removal of the uterus, the midline distance in centimeters from the anterior cervical incision to the peritoneal reflection at the lower margin of the uterine serosa was measured on the specimen using a flexible 15-cm ruler available on the sterile field. To estimate how operative conditions affect the dissection distance, the same midline measurement was also taken intraoperatively immediately before anterior colpotomy in nine patients using the same ruler (Fig. 1).
Baseline data collection included patient age, race, estrogen status, indication for surgery, and surgical procedure performed. Preoperative pelvic organ prolapse quantification was performed in patients undergoing concomitant reconstructive procedures, and staging was determined according to established criteria.8 Cervical elongation was defined as either a difference between pelvic organ prolapse quantification points C and D of greater than or equal to 8 cm or a cervical to uterine corpus length ratio greater than 0.79.9,10 Operative reports were reviewed for anterior entry surgical technique, and uterine weights and dimensions were recorded from pathology reports.
Nine embalmed cadavers with intact pelvic viscera were obtained from the Willed Body Program at the University of Texas Southwestern Medical Center in Dallas. The lower uterine segment, cervix, upper vagina, and lower urinary tract were removed en bloc from the bony pelvis and were transected in the midsagittal plane. The distance from the anterior cervicovaginal junction to the uterine anterior peritoneal reflection was measured (Fig. 2).
All cadaver measurements were taken twice with the same steel electrocardiogram caliper and flexible ruler from the operating room. Measurements for both surgical patients and cadavers were tabulated and descriptive statistics were used for data analysis and reporting using Microsoft Excel 2010.
A total of 22 surgical patients were included. Seventeen patients had concomitant pelvic reconstructive surgery, and seven had vaginal hysterectomy alone as the primary procedure. Patient baseline characteristics are outlined in Table 1. The most common surgical indications were abnormal uterine bleeding in general gynecology patients and pelvic organ prolapse in patients undergoing pelvic reconstruction. The majority of patients undergoing reconstructive surgery had stage 2 or greater uterine and anterior vaginal wall prolapse. There were 131 vaginal hysterectomies performed during the study period.
Intraoperatively, injection into the vaginal epithelium and cervical stroma before incision was performed with dilute vasopressin in four (18.2%) patients and normal saline in one (4.5%); the remainder (77.3%) had no injection. The vaginal wall was incised with the Bovie in 17 (77.3%) cases and the scalpel in five (22.7%) cases. A sharp technique was used for the entire anterior dissection in 19 (86.4%) patients, and a combination of sharp and blunt dissection was used in the remainder (13.6%). Anterior peritoneal entry was performed before clamping parametria in nine (40.9%) patients. In the remaining 13 (59.1%), posterior colpotomy and ligation of one or more pedicles of the uterosacral–cardinal ligament complex was performed before entry into the anterior cul de sac. Of these 13 cases, three (23.1%) incisions were made by direct visualization of the anterior peritoneum by digital palpation around the fundus through the posterior colpotomy. Cystoscopy was performed in all cases with pelvic reconstruction and two (33.3%) patients undergoing vaginal hysterectomy alone. There were no urinary tract injuries identified related to the vaginal hysterectomy procedure.
The median distance from the cervicovaginal incision to anterior peritoneal reflection was approximately 3.4 cm and was similar between prolapse and nonprolapse surgical patients (Table 1). When evaluated by menopausal status, the median (interquartile range) distance was 3.5 (0.9) cm in postmenopausal women (n=10) and 3.2 (1.0) cm in premenopausal women (n=12). In the nine patients in whom the intraoperative distance before colpotomy was measured in addition to specimen measurement after removal, the median (interquartile range) distance in centimeters was 3.8 (1.0) intraoperatively and 3.5 (1.8) after uterine removal. In prolapse patients, the median (interquartile range) difference between pelvic organ prolapse quantification points C and D and cervical to corpus length ratio was 3.3 (4.8) and 0.4 (0.2) cm, respectively.
For cadavers, there was limited demographic information available, but the median (interquartile range) age at death was 81 (14) years. The median (interquartile range) distance from the anterior cervicovaginal junction to the anterior peritoneal reflection was 2.7 (0.5) cm.
The main finding of this study is that the vaginal surgeon can expect a median dissection distance of approximately 3.4 cm from initial incision at the cervicovaginal junction to the anterior peritoneal reflection when performing anterior colpotomy for vaginal hysterectomy. Including premenopausal, postmenopausal, prolapse, and nonprolapse patients increases the generalizability of our findings. The median distances were greater in prolapse and postmenopausal patients, perhaps as a result of differences in uterine size, small variations in incision placement, subtle effects of prolapse, or subclinical cervical elongation. Furthermore, our intraoperative measurements at the time of colpotomy were an average of 2.9 mm longer than specimen measurements, likely resulting from the stretching effects of uterine traction during surgery.
There are scant data describing distances for anterior dissection. A MEDLINE search (1950–2016) using combinations of key terms “hysterectomy, vaginal,” “vesicocervical space,” “vesicovaginal space,” “supravaginal septum,” and “anterior colpotomy” returned no studies specifically addressing the anatomic dimensions, dissection distances, or histology of the vesicovaginal and vesicocervical spaces. Further review of selected references revealed one article describing a supravaginal septum length of 1–3 cm, depending on the size of the uterus.11 Although this latter study did not provide distance data, our range of 1.6–4.6 cm is consistent with this report with some variation likely resulting from our measurement of the total distance from initial incision to the anterior peritoneum rather than the supravaginal septum alone.
There is a paucity of data on the histologic composition of the fibers that separate the vesicovaginal from the vesicocervical space. The “supravaginal septum” is the clinical term traditionally used to describe the augmented connective tissue fibers encountered after incising the anterior vaginal wall.6,7 However, review of the literature and Terminologia Anatomica 12 did not accurately describe or recognize this structure. Despite these inconsistencies in nomenclature, this structure remains clinically relevant. Midline dissection through the supravaginal septum is recommended between 11 and 1 o'clock, because dissection too lateral in the region of the bladder pillars may result in significant bleeding and increased ureteral injury risk.6,13
Our study has several limitations. We were limited by the small sample size for both patients and cadavers and by the small range of uterine size. Our measurements describe the distance from initial incision to the lower margin of the peritoneum, and we acknowledge that the peritoneum is typically grasped and incised further cephalad than the serosal margin, resulting in a greater distance from the vaginal incision. In prolapse, although difficult anterior peritoneal entry has been recognized with cervical elongation,14 none of our patients had cervical elongation by established criteria9,10; thus, we could not draw any conclusions about its effects on dissection for anterior colpotomy. However, because the anterior peritoneum is often further away from the initial incision in these patients,14 we would expect dissection distances to be greater. All cadavers examined were embalmed and tissue shrinkage and distortion may have affected distances measured. In addition, because the cadavers were older at the time of death than the live surgical patients, age-related atrophy likely also contributed to shorter median distances in cadavers.
Based on our findings, distances significantly shorter or longer than 3 cm during anterior dissection with unclear surgical planes should prompt reevaluation, especially if significant bleeding is encountered. If difficulty is encountered, the uterosacral and lower cardinal ligaments may be clamped and transected to produce uterine descent and better exposure for anterior entry.7,13,15 If uterine size permits, the anterior peritoneum can also be identified and displaced downward by digital palpation around the fundus through a posterior colpotomy.7
Based on our clinical experience, we recommend sharp dissection of the supravaginal septum with the scissors in the midline close to the cervix with downward cervical traction and vaginal wall countertraction. The curve of the scissors should point toward the cervix with handles elevated and the fibers of the septum incised progressively cephalad between 11 and 1 o'clock.7,11,13 Further dissection should always be kept adjacent and parallel to the stroma of the anterior cervix, which can generally be palpated intraoperatively for orientation, direction, and contour to guide dissection. Deeper dissection may lead to perforation of the cervical tissue and bleeding, whereas higher dissection may lead to bladder entry. Once the supravaginal septum has been transected, a Deaver or similar retractor displaces the bladder cephalad and allows visualization or palpation of the vesicouterine peritoneal fold. Further study of the anatomy and histology of the anterior dissection plane for vaginal hysterectomy is warranted.
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