Traction force needed to reproduce physiologically observed uterine movement: technique development, feasibility assessment, and preliminary findings

Swenson, Carolyn W.; Luo, Jiajia; Chen, Luyun; Ashton‐Miller, James A.; DeLancey, John O.L.

doi:10.1007/s00192-016-2980-1

Cited by 10 publications

(7 citation statements)

References 15 publications

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“…9 For example, only a small traction force (3 oz., or the weight of a large chicken egg) is needed to cause the amount of displacement seen physiologically during maximal Valsalva in MRI. 10 This observation is consistent with the hypothesis that the levator ani muscles act to close the pelvic floor so that increases in intraabdominal pressure do not result in a downward force on the ligaments. 11,12 This is also consistent with a “slack-cord” paradigm, where movement of the uterus near its normal location is determined by the status of the pelvic floor, with the apical ligaments playing a larger role once greater degrees of descent occur.…”

Section: Commentsupporting

confidence: 90%

Intraoperative cervix location and apical support stiffness in women with and without pelvic organ prolapse

Swenson

Smith

Luo

et al. 2017

American Journal of Obstetrics and Gynecology

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Background It is unknown how initial cervix location and cervical support resistance to traction, which we term “apical support stiffness,” compare in women with different patterns of pelvic organ support. Defining a normal range of apical support stiffness is important in order to better understand the pathophysiology of apical support loss. Objective(s) The aims of our study were to: 1) determine whether women with normal apical support on clinic Pelvic Organ Prolapse Quantification (POP-Q), but with vaginal wall prolapse (cystocele and/or rectocele), have the same intraoperative cervix location and apical support stiffness as women with normal pelvic support; and 2) determine whether all women with apical prolapse have abnormal intraoperative cervix location and apical support stiffness. A third objective was to identify clinical and biomechanical factors independently associated with clinic POP-Q point C. Study Design We conducted an observational study of women with a full spectrum of pelvic organ support scheduled to undergo gynecologic surgery. All women underwent a preoperative clinic exam, including the POP-Q. Cervix starting location and the resistance (stiffness) of its supports to being moved steadily in the direction of a traction force that increased from 0 to 18 N was measured intraoperatively using a computer-controlled servoactuator device. Women were divided into three groups for analysis according to their pelvic support as classified using the clinic POP-Q: 1) “Normal/Normal” was women with normal apical (C < -5 cm) and vaginal support (Ba and Bp < 0 cm); 2) “Normal/Prolapse” had normal apical support (C < -5 cm) but prolapse of the anterior or posterior vaginal walls (Ba and/or Bp ≥ 0 cm); and 3) “Prolapse/Prolapse” had both apical and vaginal wall prolapse (C > -5 cm and Ba and/or Bp ≥ 0 cm). Demographics, intraoperative cervix locations, and apical support stiffness values were then compared. “Normal range” of cervix location during clinic exam and operative testing was defined by the total range of values observed in the Normal/Normal group. The proportion of women in each group with cervix locations within and outside the normal range was determined. Linear regression was performed to identify variables independently associated with clinic POP-Q point C. Results Fifty-two women were included—14 in the Normal/Normal group, 11 in the Normal/Prolapse group, and 27 in the Prolapse/Prolapse group. At 1 N of traction force in the operating room, 50% of women in the Normal/Prolapse group had cervix locations outside the normal range while 10% had apical support stiffness outside the normal range. Of women in the Prolapse/Prolapse group, 81% had cervix locations outside the normal range and 8% had apical support stiffness outside the normal range. Similar results for cervix locations were observed at 18 N of traction force; however the proportion of women with apical support stiffness outside the normal range increased to 50% in the Normal/Prolapse group and 59% in the Prolapse/Prolapse g...

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Section: Commentsupporting

confidence: 90%

Intraoperative cervix location and apical support stiffness in women with and without pelvic organ prolapse

Swenson

Smith

Luo

et al. 2017

American Journal of Obstetrics and Gynecology

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“…These veins contain no valves (Batson, 1940), indicating that the paracolpium can rapidly reduce its volume upon a small increase in external pressure. These findings appear to explain the 'slack cord' paradigm of DeLancey cum suis, who observed that the force necessary to displace the uterus over a distance as observed upon a Valsalva maneuver was unexpectedly small (Smith et al 2013;Swenson et al 2016). In fact, these observations strongly suggest that the large veins in the paracolpium are responsible for the absorbance of acute increases in intra-abdominal pressure, such as occur during coughing.…”

Section: The Supports Of the Vagina And Uterusmentioning

confidence: 76%

“…; Swenson et al. ). In fact, these observations strongly suggest that the large veins in the paracolpium are responsible for the absorbance of acute increases in intra‐abdominal pressure, such as occur during coughing.…”

Section: Discussionmentioning

confidence: 98%

Architectural differences in the anterior and middle compartments of the pelvic floor of young‐adult and postmenopausal females

Dabhoiwala

Hagoort

et al. 2017

Journal of Anatomy

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The pelvic floor guards the passage of the pelvic organs to the exterior. The near-epidemic prevalence of incontinence in women continues to generate interest in the functional anatomy of the pelvic floor. However, due to its complex architecture and poor accessibility, the classical 'dissectional' approach has been unable to come up with a satisfactory description, so that many aspects of its anatomy continue to raise debate. For this reason, we opted for a 'sectional' approach, using the Chinese Visible Human project (four females, 21-35 years) and the Visible Human Project (USA; one female, 59 years) datasets to investigate age-related changes in the architecture of the anterior and middle compartments of the pelvic floor. The puborectal component of the levator ani muscle defined the levator hiatus boundary. The urethral sphincter complex consisted of a circular proximal portion (urethral sphincter proper), a sling that passed on the vaginal wall laterally to attach to the puborectal muscle (urethral compressor), and a circular portion that surrounded the distal urethra and vagina (urethrovaginal sphincter). The exclusive attachment of the urethral sphincter to soft tissues implies dependence on pelvic-floor integrity for optimal function. The vagina was circular at the introitus and gradually flattened between bladder and rectum. Well-developed fibrous tissue connected the inferior vaginal wall with urethra, rectum and pelvic floor. With eight-muscle insertions, the perineal body was a strong, irregular fibrous node that guarded the levator hiatus. Only loose areolar tissue comprising a remarkably well developed venous plexus connecting the middle and superior parts of the vagina with the lateral pelvic wall. The posterolateral boundary of the putative cardinal and sacrouterine ligaments coincided with the adventitia surrounding the mesorectum. The major difference between the young-adult and postmenopausal pelvic floor was the expansion of fat in between the components of the pelvic floor. We hypothesize that accumulation of pelvic fat compromises pelvic-floor cohesion, because the pre-pubertal pelvis contains very little fibrous and adipose tissue, and fat is an excellent lubricant.

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“…42 Using these data, it can be estimated that vivo stiffness is 650 times less than seen in traditional testing. 43 Preconditioning is performed during traditional material properties testing wherein the tissue is tensioned a few times before testing is measured. 44 Since the cardinal ligaments have a lattice-like arrangement 36 , it seems likely that this preconditioning straightens the fibers so that they are all aligned, making the material properties much stiffer than would be seen when loaded in vivo, where the lattice work is open as it is during life.…”

Section: Levator Ani Musclementioning

confidence: 99%

What's new in the functional anatomy of pelvic organ prolapse?

DeLancey¹

2016

Current Opinion in Obstetrics &Amp; Gynecology

109

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Purpose of Review Provide an evidence-based review of pelvic floor functional anatomy related to pelvic organ prolapse. Recent Findings Pelvic organ support depends on interactions between the levator ani muscle and pelvic connective tissues. Muscle failure exposes the vaginal wall a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic side-wall. Birth-induced injury to the pubococcygeal portion of the levator ani muscle is seen in 55% of women with prolapse and 16% of women with normal support. Failure of the connective tissue attachments between the uterus and vagina to the pelvic wall (cardinal, uterosacral, paravaginal) are strongly related with prolapse (effect sizes ~2.5) and are also highly correlated with one another (r ~0.85). Small differences exist with prolapse in factors involving the vaginal wall length and width (effect sizes ~1). The primary difference in ligament properties between women with and without prolapse is found in ligament length. Only minor differences in ligament stiffness are seen. Summary Pelvic organ prolapse occurs due to injury to the levator ani muscles and failure of the connections between the pelvic organs to the pelvic sidewall. Abnormalities of the vaginal wall fascial tissues may play a minor role.

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Traction force needed to reproduce physiologically observed uterine movement: technique development, feasibility assessment, and preliminary findings

Cited by 10 publications

References 15 publications

Intraoperative cervix location and apical support stiffness in women with and without pelvic organ prolapse

Intraoperative cervix location and apical support stiffness in women with and without pelvic organ prolapse

Architectural differences in the anterior and middle compartments of the pelvic floor of young‐adult and postmenopausal females

What's new in the functional anatomy of pelvic organ prolapse?

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