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

Quantifying the physiologic motions of the pelvic viscera during evacuation in nulligravid asymptomatic women

INTRODUCTION AND HYPOTHESIS

Pelvic organ prolapse (POP) is often diagnosed during an in-office examination, which looks for motion of the vaginal wall while performing a strain maneuver. It is believed that the pelvic organs in adequately supported women are relatively stationary. This study was aimed at investigating the physiological displacements of pelvic organs using MR defecography.

METHODS

This prospective cohort study included 19 volunteers. Midsagittal slices representing rest and the maximum movement of the posterior vaginal fornix during three maneuvers were identified. Normalized axes for analysis were defined as the x' (line connecting the inferior-posterior-most point on the pubic symphysis to the anterior edge of the sacrococcygeal joint) and the y' (line orthogonal to the x axis that passed through the sacral promontory). The positions of the posterior vaginal fornix, mid-vagina, bladder neck, anorectal junction, and hymen were recorded. These subjects were then analyzed using the current radiological grading system of POP to determine any overlap between asymptomatic subjects and diagnostic ranges of POP.

RESULTS

Evacuation caused the most motion in the landmarks. The majority of the motion of the landmarks was along the y axis. The posterior vaginal fornix experienced significant descent (125% of the initial distance) without much anterior-posterior translation (7% of the initial distance) during defecation. All landmarks experienced similar trends.

CONCLUSIONS

We have shown that there is significant rotational motion of the pelvic organs around the pubic bone in adequately supported women. This motion when described using radiological grading is likely to be considered mild or moderate prolapse, which may contribute to overdiagnosis of POP.

Correlation of preoperative and intraoperative assessment of pelvic organ prolapse by pelvic organ prolapse quantification system

OBJECTIVE

To correlate the measurements of pelvic organ quantification (POP-Q) score obtained preoperatively with Valsalva maneuver with POP-Q score obtained intraoperatively under anesthesia in the assessment of pelvic organ prolapse.

METHODS

A prospective observational study included 25 women attending gynecology outpatient department with symptomatic pelvic organ prolapse in Midnapore Medical College, India and planned for vaginal operative treatment between March 2019 and February 2020. The preoperative examination was performed in the outpatient department using the POP-Q system with Valsalva maneuver and final examination was performed under spinal anesthesia with mechanical traction. The correlation was performed using the preoperative and intraoperative measurements.

RESULTS

All intraoperative POP-Q measurements showed a significantly higher descent compared with preoperative measurements (mean difference Aa 0.72 cm, Ba 1.08 cm, C 1.66 cm, Ap 0.26 cm, Bp 1.6 cm, D 1.6 cm, Gh 0.6 cm,) except for Pb and Tvl. Among all nine measurements, the greatest difference between the preoperative and intraoperative values was observed for points C, D, and Bp.

CONCLUSION

Preoperative POP-Q scores significantly differed when assessed intraoperatively under spinal anesthesia with traction. The patient should be informed that the surgical plan may change depending on the intraoperative findings. Our study is an alert for both surgeons and patients.

Methods for the defining mechanisms of anterior vaginal wall descent (DEMAND) study

INTRODUCTION AND HYPOTHESIS

The protocol and analysis methods for the Defining Mechanisms of Anterior Vaginal Wall Descent (DEMAND) study are presented. DEMAND was designed to identify mechanisms and contributors of prolapse recurrence after two transvaginal apical suspension procedures for uterovaginal prolapse.

METHODS

DEMAND is a supplementary cohort study of a clinical trial in which women with uterovaginal prolapse randomized to (1) vaginal hysterectomy with uterosacral ligament suspension or (2) vaginal mesh hysteropexy underwent pelvic magnetic resonance imaging (MRI) at 30-42 months post-surgery. Standardized protocols have been developed to systematize MRI examinations across multiple sites and to improve reliability of MRI measurements. Anatomical failure, based on MRI, is defined as prolapse beyond the hymen. Anatomic measures from co-registered rest, maximal strain, and post-strain rest (recovery) sequences are obtained from the "true mid-sagittal" plane defined by a 3D pelvic coordinate system. The primary outcome is the mechanism of failure (apical descent versus anterior vaginal wall elongation). Secondary outcomes include displacement of the vaginal apex and perineal body and elongation of the anterior wall, posterior wall, perimeter, and introitus of the vagina between (1) rest and strain and (2) rest and recovery.

RESULTS

Recruitment and MRI trials of 94 participants were completed by May 2018.

CONCLUSIONS

Methods papers which detail studies designed to evaluate anatomic outcomes of prolapse surgeries are few. We describe a systematic, standardized approach to define and quantitatively assess mechanisms of anatomic failure following prolapse repair. This study will provide a better understanding of how apical prolapse repairs fail anatomically.

Transvaginal round-infundibulopelvic ligament colposuspension after vaginal hysterectomy in high-grade uterovaginal prolapse: 11-year outcome

OBJECTIVE

To interpret the long-term outcomes of transvaginal round-infundibulopelvic ligament colposuspension after vaginal hysterectomy in patients with stage 3-4 uterovaginal prolapse.

STUDY DESIGN

This retrospective case-control study from 2007 to 2016 analysed patients' medical records and evaluated gynaecological examinations over 11 years of follow-up. One hundred and forty-three patients who underwent transvaginal round-infundibulopelvic ligament colposuspension after vaginal hysterectomy were evaluated. The prespecified primary outcome evaluated at 11-year follow-up was apical prolapse of stage 2 or higher evaluated by the Pelvic Organ Prolapse Quantification System (POP-Q), in combination with bothersome bulge symptoms or repeat surgery for recurrent apical prolapse. The secondary outcome was overall anatomical failure (recurrent prolapse of stage 2 or higher in apical, anterior or posterior compartment). The rate of recurrence of apical prolapse was compared between groups using the McNemar test.

RESULTS

The mean (± standard deviation) follow-up period was 88.15 ± 2.519 months (95 % confidence interval 83.17-93.13). The pre-operative diagnoses were stage 3 uterovaginal prolapse in 23 (16.08 %) patients, stage 4 uterovaginal prolapse in 120 (83.91 %) patients, rectocele in 119 (83.21 %) patients, cystocele in 138 (96.50 %) patients and stress urinary incontinence in 53 (37.06 %) patients. Ten (8.33 %) patients with stage 4 uterovaginal prolapse developed postoperative apical prolapse, whereas none of the patients with stage 3 uterovaginal prolapse developed postoperative apical prolapse. Postoperatively, the POP-Q stages of apical prolapse were significantly lower compared with pre-operatively (p < 0.001). Postoperatively, the apical prolapse rate was 7.0 %, the recurrent cystocele rate was 2.07 %, the recurrent rectocele rate was 5.5 %, and the recurrent stress urinary incontinence rate was 18.87 %. Overall, postoperative anatomical failure occurred in 21 of 143 (14.68 %) women. One (0.69 %) patient developed perioperative bladder perforation, two (1.39 %) patients experienced voiding difficulty, and eight (5.59 %) patients experienced vaginal spotting.

CONCLUSION

Transvaginal round-infundibulopelvic ligament colposuspension during vaginal hysterectomy is an effective and useful method that reduces the rate of postoperative apical prolapse in patients with high-grade uterovaginal prolapse.

From molecular to macro: the key role of the apical ligaments in uterovaginal support

To explain the pathophysiology of pelvic organ prolapse, we must first understand the complexities of the normal support structures of the uterus and vagina. In this review, we focus on the apical ligaments, which include the cardinal and uterosacral ligaments. The aims of this review are the following: (1) to provide an overview of the anatomy and histology of the ligaments; (2) to summarize the imaging and biomechanical studies of the ligament properties and the way they relate to anterior and posterior vaginal wall prolapse; and (3) to synthesize these findings into a conceptual model for the progression of prolapse.

Motion of the vaginal apex during strain and defecation

INTRODUCTION AND HYPOTHESIS

Although the main function of the suspensory ligaments of the vaginal apex is to prevent its descent toward the vaginal introitus, there remains limited information regarding its normal physiological motion. This study was aimed at quantifying the motion of the non-prolapsed vaginal apex during strain and defecation maneuvers.

METHODS

This study represents a sub-analysis of a parent study that was aimed at evaluating rectal mobility with regard to obstructed defecation symptoms. Patients with normal apical vaginal support who had undergone MR defecography were entered into the study. For each patient, midsagittal images at rest, maximum strain, and maximum evacuation were utilized. The location of the cervicovaginal junction, S4-S5 intervertebral disc, sacral promontory, and hymen were identified. Vectors were calculated from each of these landmarks to the vaginal apex to compare vector angles and magnitudes across subjects.

RESULTS

Twelve patients were included in this study. At rest, the vagina extends from the hymen, which is inferior and posterior to the inferior symphysis pubis, to the vaginal apex at an angle of 45.2° ± 14.5° relative to the pubococcygeal line. This angle became more acute with strain and even more so during maximum evacuation (14.1° ± 9.0°, p < 0.001). Differences in the vector magnitude, although not statistically significant, showed a trend indicating shorter lengths with maximum evacuation.

CONCLUSIONS

The vaginal apex is a highly mobile structure demonstrating significantly more mobility during defecation compared with strain. The data obtained contradict the general perception that the vaginal apex is relatively fixed within the pelvis of normally supported women.

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

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 to a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic sidewall. 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 lateral connective tissue attachments between the uterus and vagina to the pelvic wall (cardinal, uterosacral, and 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 because of injury to the levator ani muscles and failure of the lateral connections between the pelvic organs to the pelvic sidewall. Abnormalities of the vaginal wall fascial tissues may play a minor role.

Female pelvic floor biomechanics: bridging the gap

PURPOSE OF REVIEW

The pelvic floor is a complex assembly of connective tissues and striated muscles that simultaneously counteracts gravitational forces, inertial forces, and intra-abdominal pressures while maintaining the position of the pelvic organs. In 30% of women, injury or failure of the pelvic floor results in pelvic organ prolapse. Surgical treatments have high recurrence rates, due, in part, to a limited understanding of physiologic loading conditions. It is critical to apply biomechanics to help elucidate how altered loading conditions of the pelvis contribute to the development of pelvic organ prolapse and to define surgeries to restore normal support.

RECENT FINDINGS

Evidence suggests the ewe is a potential animal model for studying vaginal properties and that uterosacral and cardinal ligaments experience significant creep, which may be affecting surgical outcomes. A new method of measuring ligament displacements in vivo was developed, and finite element models that simulate urethral support, pelvic floor dynamics, and the impact of episiotomies on the pelvic floor were studied.

SUMMARY

The current review highlights some contributions over the past year, including mechanical testing and the creation of models, which are used to understand pelvic floor changes with loading and the impact of surgical procedures, to illustrate how biomechanics is being utilized.

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

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.

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

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 to better understand the pathophysiology of apical support loss.

OBJECTIVE

The aims of our study were to determine whether: (1) women with normal apical support on clinic Pelvic Organ Prolapse Quantification, 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) 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 Pelvic Organ Prolapse Quantification 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 examination, including Pelvic Organ Prolapse Quantification. Cervix starting location and the resistance (stiffness) of its supports to being moved steadily in the direction of a traction force that increased from 0-18 N was measured intraoperatively using a computer-controlled servoactuator device. Women were divided into 3 groups for analysis according to their pelvic support as classified using the clinic Pelvic Organ Prolapse Quantification: (1) "normal/normal" was women with normal apical (C < -5 cm) and vaginal (Ba and Bp < 0 cm) support; (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 examination 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 Pelvic Organ Prolapse Quantification point C.

RESULTS

In all, 52 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 group. The prolapse/prolapse group had statistically lower apical support stiffness compared to the normal/normal group with increased traction from 1-18 N (0.47 ± 0.18 N/mm vs 0.63 ± 0.20 N/mm, P = .006), but all other comparisons were nonsignificant. After controlling for age, parity, body mass index, and apical support stiffness, cervix location at 1 N traction force remained an independent predictor of clinic Pelvic Organ Prolapse Quantification point C, but only in the prolapse/prolapse group.

CONCLUSION

Approximately 50% of women with cystocele and/or rectocele but normal apical support in the clinic had cervix locations outside the normal range under intraoperative traction, while 19% of women with uterine prolapse had normal apical support. Identifying women whose apical support falls outside a defined normal range may be a more accurate way to identify those who truly need a hysterectomy and/or an apical support procedure and to spare those who do not.