Postpartum Changes in Levator Plate Shape and Genital Hiatus Size After Vaginal Delivery.

INTRODUCTION AND HYPOTHESIS: Vaginal delivery is a risk factor for pelvic organ prolapse. We sought to quantify changes in level III pelvic support measurements at 7 weeks and 8 months following vaginal delivery. METHODS: This secondary analysis included primiparous women who underwent pelvic MRI and clinical examinations at 7 weeks and 8 months after vaginal delivery. Demographics and obstetrical data were abstracted. Mid-sagittal resting MRIs were used to perform level III measurements including urogenital hiatus (UGH), levator hiatus (LH), and mid-sagittal levator area (LA), and to trace the levator plate (LP). Using principal component analysis, 7-week and 8-month principal component scores (PC1s) and MRI measurements were compared using paired t test. If the PC1 score change from 7 weeks to 8 months was > 0, women were considered to have a more dorsally oriented LP shape. RESULTS: Of 76 participants, POP-Q values did not significantly differ between 7 weeks and 8 months, but MRI measurements improved (UGH: 3.9 ± 0.8 vs 3.5 ± 0.8, p < 0.001; LH: 5.4 ± 0.8 vs 5.2 ± 0.8, p = 0.01; LA: 18.0 ± 6.0 vs 15.2 ± 6.5, p < 0.001). Approximately 30% (22 out of 76) had a more dorsally oriented LP shape and larger level III measurements at 8 months than women with a more ventrally oriented LP shape (LA: 86.4% vs 1.9%, p < 0.001; LH: 16% vs 12%, p < 0.001; UGH: 59.1% vs 3.7%, p < 0.001). CONCLUSIONS: After vaginal delivery, most women had "recovery" of level III support-defined by smaller UGH, LH, and LA measurements-and a more ventrally oriented LP shape. However, nearly 30% had larger level III measurements and a more dorsally oriented LP shape, indicating "impaired recovery" of support.

Overactive Bladder in Late Pregnancy to 1 Year After First Vaginal Delivery.

IMPORTANCE: Understanding overactive bladder (OAB) during pregnancy and postpartum may increase our knowledge of pathophysiology. OBJECTIVES: The purpose of this study was to understand the prevalence and severity of OAB during pregnancy through 1 year postpartum as well as the associated factors. STUDY DESIGN: This is a secondary analysis of a prospective cohort study evaluating primiparous women with a singleton term vaginal delivery assessed at the third trimester, 8 weeks postpartum, and 1 year postpartum. Overactive bladder was defined as urinary urgency plus nocturia or frequency, or urgency urinary incontinence (UUI). Overactive bladder severity was defined using average visual analog scores (0-100) from OAB symptoms on the Epidemiology of Prolapse and Incontinence Questionnaire. We evaluated associations with OAB at each time point using logistic regression. RESULTS: Among 579 participants, mean age was 29 years. Overactive bladder prevalence was higher at 8 weeks postpartum (23%) than at the third trimester (18%, P = 0.03) and 1 year postpartum (19%, P = 0.03). Overactive bladder severity was higher at the third trimester (42.2) than at 8 weeks postpartum (23.3, P = 0.008), but not at 1 year postpartum (29.1, P = 0.1). In those with OAB, UUI severity was higher at 1 year postpartum compared with that at the third trimester ( P = 0.02). Younger age was associated with third trimester OAB. At 8 weeks postpartum, OAB was associated with older age, urinary tract infection after delivery, birth weight ≥3,500 g, and third trimester OAB. At 1 year postpartum, OAB was associated with birth weight ≥3,500 g and third trimester OAB. CONCLUSIONS: Overactive bladder affects 1 in 5 primiparous women during pregnancy or after vaginal delivery. The increased severity of UUI postpartum and the association between higher birth weight and OAB postpartum suggest an effect of delivery.

Association Between Genital Hiatus Size 8 Weeks Postpartum and Pelvic Organ Prolapse 1 Year After the First Vaginal Delivery.

IMPORTANCE: Evidence suggests that genital hiatus (GH) enlargement precedes pelvic organ prolapse development remote from delivery. However, the association of postpartum GH enlargement and prolapse is unknown. OBJECTIVE: The aim of this study was to determine the association between enlarged GH at 8 weeks postpartum and prolapse 1 year after first vaginal delivery. STUDY DESIGN: This is a secondary analysis of the Motherhood and Pelvic Health study, a prospective cohort of women after their first vaginal delivery. Enlarged GH was defined as ≥4 cm. Prolapse was defined as Pelvic Organ Prolapse Quantification points Ba, Bp, or C at or beyond the hymen. Kaplan-Meier analysis and proportional hazards modeling were used to analyze the association between enlarged GH at 8 weeks postpartum and prolapse at 1 year postpartum. Diagnostic test characteristics of enlarged GH were calculated. RESULTS: Five hundred eighty women were included. At 1 year postpartum, the prevalence of prolapse was 3 times higher in women with, versus without, an enlarged GH at 8 weeks postpartum (16% vs 5%, P < 0.001). This was confirmed in a Cox proportional hazards model while adjusting for age, body mass index, and early postpartum prolapse (adjusted hazard ratio, 3.3; 95% confidence interval, 1.85-6.06; P < 0.001). The diagnostic properties of postpartum GH to predict prolapse at 1 year are as follows: sensitivity, 0.63; specificity, 0.67; positive predictive value, 0.17; and negative predictive value, 0.95. CONCLUSIONS: Women with an enlarged GH at 8 weeks postpartum have a 3.3-fold increased risk of prolapse at 1 year. As a screening tool, GH <4 cm at 8 weeks postpartum has high negative predictive value.

A comparison of MRI-based pelvic floor support measures between young and old women with prolapse.

INTRODUCTION AND HYPOTHESIS: We sought to 1) test the hypothesis that young women (≤45 years) with pelvic organ prolapse have a higher prevalence of major levator ani muscle (LAM) defects than old women (≥70 years) with prolapse and 2) compare level II/III measurements between young and old women with prolapse and age-matched controls to evaluate age-related mechanistic differences in the disease process. METHODS: A secondary analysis examined four groups of parous women: young prolapse (YPOP, n = 17); old prolapse (OPOP, n = 17); young controls (YC, n = 15); old controls, (OC, n = 13). Prolapse was defined as any compartment at or beyond the hymen with vaginal bulge symptoms. Genital hiatus (GH) was measured on clinical exam. Major LAM defects and level II/III measurements (UGH: urogenital hiatus, LA: levator area, and apex location) were assessed on MRI at rest and strain, and the difference (Δ) between measurements calculated. Principal component analysis was used to evaluate levator plate (LP) shape. RESULTS: Major LAM defects occurred in 42% of YPOP and 47% of OPOP (p > .99). GHrest was 1.5 cm larger in OPOP versus YPOP (p < .001) and 2 cm larger in OPOP versus OC (p < .001). Regardless of prolapse status, LArest and UGHrest on MRI increased with age. YPOP had larger ΔLA (p = .04), ΔUGH (p = .03), and Δapex than OPOP (p = .01). Resting LP shape was more dorsally oriented in OPOP versus YPOP (p = .02) and OC versus YC (p = .004). CONCLUSIONS: Prolapse in young women cannot be solely explained by a higher LAM defect prevalence. GH size and other measures of level II/III pelvic support worsen with age regardless of prolapse status.

Comparison of in vivo visco-hyperelastic properties of uterine suspensory tissue in women with and without pelvic organ prolapse.

The uterine suspensory tissue (UST) complex includes the cardinal (CL) and uterosacral "ligaments" (USL), which are mesentery-like structures that play a role in resisting pelvic organ prolapse (POP). Since there is no information on the time-dependent material properties of the whole structure in situ and in vivo, we developed and tested an intraoperative technique to quantify in vivo whether there is a significant difference in visco-hyperelastic behavior of the CL and USL between women with and without POP. Thirteen women with POP (cases) and four controls scheduled for surgery were selected from an ongoing POP study. Immediately prior to surgery, a computer-controlled linear servo-actuator with a series force transducer applied a continuous, caudally directed traction force while simultaneously recording the resulting cervical displacement in the same direction. After applying an initial 1.1 N preload, a ramp rate of 4 mm/s was used to apply a maximum force of 17.8 N in three "ramp-and-hold" test trials. A simplified bilateral four-cable biomechanical model was used to identify the material behavior of each ligament. For this, the initial cross-section areas of the CL and USL were measured on 3-T magnetic resonance image-based 3D models from each subject. The time-dependent strain energy function of CL/USL was defined with a three-parameter hyperelastic Mooney-Rivlin material model and a two-term Prony series in relaxation form. When cases were compared with controls, the estimated time-dependent material constants of CL and USL did not differ significantly. These are the first measurements that compare the in vivo and in situ visco-hyperelastic response of the tissues comprising the CL and USL to loading in women with and without prolapse. Larger sample sizes would help improve the precision of intergroup differences.

Hiatal failure: effects of pregnancy, delivery, and pelvic floor disorders on level III factors.

INTRODUCTION AND HYPOTHESIS: The failure of the levator hiatus (LH) and urogenital hiatus (UGH) to remain closed is not only associated with pelvic floor disorders, but also contributes to recurrence after surgical repair. Pregnancy and vaginal birth are key events affecting this closure. An understanding of normal and failed hiatal closure is necessary to understand, manage, and prevent pelvic floor disorders. METHODS: This narrative review was conducted by applying the keywords "levator hiatus" OR "genital hiatus" OR "urogenital hiatus" in PubMed. Articles that reported hiatal size related to pelvic floor disorders and pregnancy were chosen. Weighted averages for hiatal size were calculated for each clinical situation. RESULTS: Women with prolapse have a 22% and 30% larger LH area measured by ultrasound at rest and during Valsalva than parous women with normal support. Women with persistently enlarged UGH have 2-3 times higher postoperative failure rates after surgery for prolapse. During pregnancy, the LH area at Valsalva increases by 29% from the first to the third trimester in preparation for childbirth. The enlarged postpartum hiatus recovers over time, but does not return to nulliparous size after vaginal birth. Levator muscle injury during vaginal birth, especially forceps-assisted, is associated with increases in hiatal size; however, it only explains a portion of hiatus variation-the rest can be explained by pelvic muscle function and possibly injury to other level III structures. CONCLUSIONS: Failed hiatal closure is strongly related to pelvic floor disorders. Vaginal birth and levator injury are primary factors affecting this important mechanism.

Age, parity, and prolapse: interaction and influence on levator bowl volume.

INTRODUCTION AND HYPOTHESIS: The objective was to test the hypotheses that a linear relationship exists between age and levator bowl volume (LBV); and that age, parity, and prolapse are independently associated with LBV. METHODS: We conducted a secondary analysis of data from nulliparous women, parous controls, and prolapse (Pelvic Organ Prolapse Quantification (POP-Q) Ba ≥ 1 cm) cases from each of three age groups: young (≤40), mid-age (50-60), and older (≥70). LBV was measured using MRI at rest and Valsalva as the 3D space contained above the levator ani muscles and below the sacrococcygeal junction-to-inferior pubic point reference plane. Linear regression models were used to examine the effects of age, parity, prolapse, and their interactions (age*parity and age*prolapse) on LBV. RESULTS: Each group consisted of 9-12 women. LBVRest increased with age in a nonlinear fashion. For nulliparous women, the median value increased 4.7% per decade from the young to mid-age group and 84% per decade from the mid-age to older group; for parous controls, the corresponding increases were 38% and -0.5%; and for women with prolapse, they were 46% and 11%. Age and prolapse status (both p<0.001) were found to be significant independent predictors of LBVRest. Interactions between age*prolapse (p=0.003) and age*parity (p=0.045) were also independently associated with LBVRest. CONCLUSIONS: Parity and prolapse influence how age affects LBVRest. In nulliparous women, age had little effect on LBVRest until after mid-age. For women with prolapse, LBVRest increased at a much earlier age, with the biggest difference occurring between young and mid-age women.

Antibiotic use during repair of obstetrical anal sphincter injury: a quality improvement initiative.

OBJECTIVE: To evaluate the effects of a quality improvement initiative regarding the administration of antibiotics at the time of obstetric anal sphincter injury (OASIS) repair. METHODS: At University of Michigan-a tertiary care center in Ann Arbor, MI, USA, we implemented a quality improvement intervention aimed at administering a single dose of broad-spectrum antibiotics at the time of OASIS repair. Best practice recommendations and reminders were presented to the department. Cefazolin plus metronidazole or clindamycin plus gentamycin were the recommended antibiotics. The effects of this intervention were assessed based on a chart review of deliveries between January 4, 2014 and February 13, 2019, which included patient data both pre-initiative and post-initiative to compare the prevalence of antibiotic use at the time of OASIS repair. RESULTS: Recommended antibiotic use increased from 0.3% (1/372) pre-initiative to 75.7% (106/140) post-initiative (P < 0.001), and any antibiotic use increased from 6.5% (24/372) to 82.9% (116/140, P < 0.001). The proportion of cases complicated by wound infection/breakdown decreased by 55% after the quality improvement intervention (3.2% pre-intervention vs 1.4% post-intervention, P = 0.22). CONCLUSION: Following a departmental quality improvement intervention aimed at increasing antibiotic administration at the time of OASIS repair, antibiotic use increased 13-fold. Although underpowered to detect a significant difference in wound complications, our study showed a clinically meaningful decrease in wound infection/breakdown with antibiotic administration.

Changes in cardinal ligament length and curvature with parity and prolapse and their relation to level III hiatus measures.

INTRODUCTION AND HYPOTHESIS: Test the hypotheses that (1) cardinal ligament (CL) straightening and lengthening occur with parity and prolapse, (2) CL straightening occurs before lengthening, and (3) CL length is correlated with level III measures. METHODS: We performed a secondary analysis of MRIs from women in three groups: (1) nulliparous with normal support, (2) parous with normal support, and (3) uterine prolapse (POP-Q point C > - 4 and Ba > 1 cm). The 3D stress MRI images at rest and maximal Valsalva were analyzed. CLs were traced from their origin to cervico-vaginal insertions. Curvature ratio was calculated as curved length/straight length. Level III measures included urogenital hiatus (UGH), levator hiatus (LH), and levator bowl volume (LBV), and their correlations with CL length were calculated. RESULTS: Ten women were included in each group. Compared to the nulliparous group, CL length was 18% longer in parous controls (p = .04) and 59% longer with prolapse (p < .01) at rest, while at Valsalva, CL length was 10% longer in parous controls (p = .21) and 49% longer with prolapse (p < .01). Curvature ratios showed 18% more straightening in women with prolapse compared to parous controls (p < .01). Curved CL length and level III measures were moderately to strongly correlated: UGH (rest: R = 0.68, p < .01; Valsalva: R =0.80, p < .01), LH (rest: R = 0.60, p < .01; Valsalva: R = 0.78, p < .01), and LBV (rest: R = 0.71, p < .01; Valsalva: R =0.89, p < .01). CONCLUSION: Our findings suggest that the CLs undergo three times as much lengthening with prolapse as with parity; however, straightening only occurs with prolapse. Strong correlations exist between level I and level III support.

Development of a Preoperative Clinical Risk Assessment Tool for Postoperative Complications After Hysterectomy.

STUDY OBJECTIVE: To develop a preoperative risk assessment tool that quantifies the risk of postoperative complications within 30 days of hysterectomy. DESIGN: Retrospective analysis. SETTING: Michigan Surgical Quality Collaborative hospitals. PATIENTS: Women who underwent hysterectomy for gynecologic indications. INTERVENTIONS: Development of a nomogram to create a clinical risk assessment tool. MEASUREMENTS AND MAIN RESULTS: Postoperative complications within 30 days were the primary outcome. Bivariate analysis was performed comparing women who had a complication and those who did not. The patient registry was randomly divided. A logistic regression model developed and validated from the Collaborative database was externally validated with hysterectomy cases from the National Surgical Quality Improvement Program, and a nomogram was developed to create a clinical risk assessment tool. Of the 41,147 included women, the overall postoperative complication rate was 3.98% (n = 1638). Preoperative factors associated with postoperative complications were sepsis (odds ratio [OR] 7.98; confidence interval [CI], 1.98-32.20), abdominal approach (OR 2.27; 95% CI, 1.70-3.05), dependent functional status (OR 2.20; 95% CI, 1.34-3.62), bleeding disorder (OR 2.10; 95% CI, 1.37-3.21), diabetes with HbA1c ≥9% (OR 1.93; 95% CI, 1.16-3.24), gynecologic cancer (OR 1.86; 95% CI, 1.49-2.31), blood transfusion (OR 1.84; 95% CI, 1.15-2.96), American Society of Anesthesiologists Physical Status Classification System class ≥3 (OR 1.46; 95% CI, 1.24-1.73), government insurance (OR 1.3; 95% CI, 1.40-1.90), and body mass index ≥40 (OR 1.25; 95% CI, 1.04-1.50). Model discrimination was consistent in the derivation, internal validation, and external validation cohorts (C-statistics 0.68, 0.69, 0.68, respectively). CONCLUSION: We validated a preoperative clinical risk assessment tool to predict postoperative complications within 30 days of hysterectomy. Modifiable risk factors identified were preoperative blood transfusion, poor glycemic control, and open abdominal surgery.

Analysis of long-term structural failure after native tissue prolapse surgery: a 3D stress MRI-based study.

INTRODUCTION AND HYPOTHESIS: We sought to identify postoperative structural failure sites associated with long-term prolapse recurrence and their association with symptoms and satisfaction. METHODS: Women who had a research MRI prior to native-tissue prolapse surgery were recruited for examination, 3D stress MRI, and questionnaires. Recurrence was defined by Pelvic Organ Prolapse Quantification System (POP-Q)Ba/Bp > 0 or C > -4. Measurements were performed at rest and maximum Valsalva ("strain") including vaginal length, apex location, urogenital hiatus (UGH), and levator hiatus (LH). Measures were compared between subjects and to women with normal support. Failure frequency was the proportion of women with measurements outside the normal range. Symptoms and satisfaction were measured using validated questionnaires. RESULTS: Thirty-one women participated 12.7 years after surgery-58% with long-term success and 42% with recurrence. Failure site comparisons between success and failure were: impaired mid-vaginal paravaginal support (62% vs. 28%, p = 0.01), longer vaginal length (54% vs. 22%, p = 0.03), and enlarged urogenital hiatus (54% vs. 22%, p = 0.03). Apical paravaginal location had the lowest failure frequency (recurrence: 15% vs. success: 7%, p = 0.37). Patient satisfaction was high (recurrence: 5.0 vs. success: 5.0, p = 0.86). Women with bothersome bulge symptoms had a 33% larger UGH strain on POP-Q (p = 0.01), 8.7% larger resting UGH (p = 0.046), 11.5% larger straining LH (p = 0.01), and 9.3% larger resting LH (p = 0.01). CONCLUSIONS: Abnormal low mid-vaginal paravaginal location (Level II), long vaginal length (Level II), and large UGH (Level III) were associated with long-term prolapse recurrence. Patient satisfaction was high and unrelated to anatomical recurrence. Bothersome bulge symptoms were associated with hiatus enlargement.

Preoperative level II/III MRI measures predicting long-term prolapse recurrence after native tissue repair.

INTRODUCTION AND HYPOTHESIS: To identify preoperative level II/III MRI measures associated with long-term recurrence after native tissue prolapse repair. METHODS: Women who previously participated in pelvic floor research involving MRI prior to undergoing primary native tissue prolapse repair were recruited to return for repeat examination and MRI. Recurrence was defined by POP-Q (Ba/Bp > 0 or C > -4), repeat surgery, or pessary use. Preoperative MR images were used to perform five level II/III measurements including a new levator plate (LP) shape analysis at rest and maximal Valsalva. Principal component analysis (PCA) was used to evaluate LP shape variations. Principal component scores calculated for two independent shape variations were noted. RESULTS: Thirty-five women were included with a mean follow-up of 13.2 ± 3.3 years. Nineteen (54%) were in the success group. There were no statistical differences between success versus recurrence groups in demographic, clinical, or surgical characteristics. Women with recurrence had a larger preoperative resting levator hiatus [median 6.4 cm (IQR 5.7, 7.1) vs. 5.8 cm (IQR 5.3, 6.3), p = 0.03]. This measure was associated with increased odds of recurrence (OR 8.2, CI 1.4-48.9, p = 0.02). Using PCA, preoperative LP shape PC1 scores were different between success and recurrence groups (p = 0.02), with a more dorsally oriented LP shape associated with recurrence. CONCLUSIONS: Larger preoperative levator hiatus at rest and a more dorsally oriented levator plate shape were associated with prolapse recurrence at long-term follow-up. For every 1 cm increase in preoperative resting levator hiatus, the odds of long-term prolapse recurrence increases 8-fold.

A new 3D stress MRI measurement strategy to quantify surgical correction of prolapse in three support systems.

AIMS: The aim of this study was to develop and test the feasibility of a magnetic resonance imaging (MRI)-based measurement strategy to evaluate the effectiveness of surgical procedures in restoring normal anatomy in all three systems of pelvic floor support and quantify the structural changes induced by prolapse surgery. METHODS: Patients underwent clinical examination and stress MRI preoperatively and again 3 months postoperatively. Preoperative and postoperative measures of three MRI-based structural support systems were made: (1) vaginal wall, (2) apical and paravaginal support, and (3) hiatal closure system. Preoperative to postoperative structural changes were calculated and compared to normal values, and bivariate associations were determined. RESULTS: The three structural support systems were successfully quantified for both preoperative and postoperative MRIs regardless of operative approaches in all 15 women in the pilot group. Apical support was restored to normal in 11 of 12 patients who underwent an apical suspension procedure and 9 of 14 patients with a posterior repair had normalization of genital hiatus size. Mid-vaginal paravaginal location was elevated an average of 2.5 ± 2.0 cm despite no paravaginal repairs being performed. Paravaginal location improvements were also significantly correlated with apical elevation (r values 0.99-0.87, p < 0.001). CONCLUSIONS: A strategy that quantifies structural-specific preoperative impairments and improvements after prolapse surgery was successfully developed. Early findings reveal that prolapse surgery is more successful in restoring normal anatomy at Level I than Level III. Improvement in paravaginal location is significantly correlated with apical elevation.

Does preoperative resting genital hiatus size predict surgical outcomes?

AIM: To determine whether preoperative genital hiatus at rest is predictive of medium-term prolapse recurrence. METHODS: We conducted a retrospective study of women who underwent native tissue prolapse surgery from 2002 to 2017 with pelvic organ prolapse quantification data including resting genital hiatus at one of three time points: preoperatively, 6 weeks, and ≥1 year postoperatively. Demographics and clinical data were abstracted from the chart. Prolapse recurrence was defined by anatomic outcomes (Ba > 0, Bp > 0, and/or C ≥ -4) or retreatment. Descriptive statistics, bivariate analyses, and logistic regression analyses were performed. RESULTS: Of the 165 women included, 36 (21.8%) had prolapse recurrence at an average of 1.5 years after surgery. Preoperative resting genital hiatus did not differ between women with surgical success versus recurrence (3.5 cm [interquartile range, IQR 2.25, 4.0) vs 3.5 cm (IQR 3.0, 4.0), p = 0.71). Point Bp was greater in the recurrence group at every time point. Preoperative Bp (odds ratio [OR] 1.24, confidence interval [CI] [1.06-1.45], p = 0.01) and days from surgery (OR 1.001, CI [1.000-1.001], p < 0.01) were independently associated with recurrence. Preoperative genital hiatus at rest and strain were significantly larger among women who underwent a colpoperineorrhaphy (rest: 4.0 [3.0, 4.5] cm vs 3.5 [3.0, 4.0] cm, p < 0.01; strain: 6.0 [4.0, 6.5] cm vs 5.0 [4.0, 6.0] cm, p = 0.01). CONCLUSIONS: Preoperative genital hiatus at rest was not associated with prolapse recurrence when the majority of women underwent colpoperineorrhaphy. Preoperative Bp was more predictive of short-term prolapse recurrence. For every 1 cm increase in point Bp, there is a 24% increased odds of recurrence.

Genome-Wide Association Study of Pelvic Organ Prolapse Using the Michigan Genomics Initiative.

OBJECTIVES: The aim of this study was to (1) replicate previously identified genetic variants significantly associated with pelvic organ prolapse and (2) identify new genetic variants associated with pelvic organ prolapse using a genome-wide association study. METHODS: Using our institution's database linking genetic and clinical data, we identified 1,329 women of European ancestry with an International Classification of Diseases, Ninth Revision (ICD-9)/ICD-10 code for prolapse, 767 of whom also had Current Procedural Terminology (CPT)/ICD-9/ICD-10 procedure codes for prolapse surgery, and 16,383 women of European ancestry older than 40 years without a prolapse diagnosis code as controls. Patients were genotyped using the Illumina HumanCoreExome chip and imputed to the Haplotype Reference Consortium. We tested 20 million single nucleotide polymorphisms (SNPs) for association with pelvic organ prolapse adjusting for relatedness, age, chip version, and 4 principal components. We compared our results with 18 previously identified genome-wide significant SNPs from the UK Biobank, Commun Biol (2020;3:129), and Obstet Gynecol (2011;118:1345-1353). RESULTS: No variants achieved genome-wide significance (P = 5 × 10-8). However, we replicated 4 SNPs with biologic plausibility at nominal significance (P ≤ 0.05): rs12325192 (P = 0.002), rs9306894 (P = 0.05), rs1920568 (P = 0.034), and rs1247943 (P = 0.041), which were all intergenic and nearest the genes SALL1, GDF7, TBX5, and TBX5, respectively. CONCLUSIONS: Our replication of 4 biologically plausible previously reported SNPs provides further evidence for a genetic contribution to prolapse, specifically that rs12325192, rs9306894, rs1920568, and rs1247943 may contribute to susceptibility for prolapse. These and previously reported associations that have not yet been replicated should be further explored in larger, more diverse cohorts, perhaps through meta-analysis.

Novel 3D MRI technique to measure perineal membrane structural changes with pregnancy and childbirth: Technique development and measurement feasibility.

INTRODUCTION AND HYPOTHESIS: We aimed to develop and validate a new MRI-based perineal membrane reconstruction and morphological measurement technique, and test its feasibility on nulliparous and parous women to determine the effects of pregnancy and childbirth on the perineal membrane. METHODS: The perineal membrane was traced on high-resolution MRI using 3D Slicer® and analyses performed using Rhinoceros 6.0 SR23®. Validation was done by comparing MRI-based perineal membrane reconstruction to dissection measurements in a cadaver. Feasibility of reconstruction was assessed in the following three groups: nulliparous (NP), primiparous women who underwent cesarean delivery (CD), and primiparous women with vaginal delivery (VD). The following parameters were measured: (1) swinging door angle, (2) bony and (3) soft tissue attachment lengths, (4) separation at perineal body level, (5) surface area, and (6) hiatal area. ANOVA and post-hoc comparisons were performed, and the effect sizes (d) were reported. RESULTS: Model reconstruction was similar to cadaver dissection findings. Morphological measurements were feasible in all women (NP, n = 10; CS, n = 6; VD, n = 19). Swinging door angle was 13o greater in CD (p = 0.03; d = 1.15) and 16o greater in VD (p < 0.001; d = 1.41) compared to NP. VD showed 13% larger separation at the perineal body than NP (p = 0.097, d = 0.84) and 23% larger hiatal area than CD (p = 0.14, d = 0.94). CONCLUSION: This novel and anatomically validated MRI-based perineal membrane reconstruction technique is feasible. Preliminary findings show that pregnancy and childbirth both influence perineal membrane morphology with VD being associated with the largest swinging door angle and perineal body separation.