Ultrasound examination of the pelvic floor during active labor: A longitudinal cohort study.

INTRODUCTION: There is limited evidence about changes in the pelvic floor during active labor. We aimed to investigate changes in hiatal dimensions during the active first stage of labor and associations with fetal descent and head position. MATERIAL AND METHODS: We conducted a longitudinal, prospective cohort study at the National University Hospital of Iceland, from 2016 to 2018. Nulliparous women with spontaneous onset of labor, a single fetus in cephalic presentation, and gestational age ≥37 weeks were eligible. Fetal position was assessed with transabdominal ultrasound and fetal descent was measured with transperineal ultrasound. Three-dimensional volumes were acquired from transperineal scanning at the start of the active phase of labor and in late first stage or early second stage. The largest transverse hiatal diameter was measured in the plane of minimal hiatal dimensions. The levator urethral gap was measured as the distance between the center of the urethra and the levator insertion using tomographic ultrasound imaging. Measurements of the levator urethral gap were made in the plane of minimal hiatal dimensions and 2.5 and 5 mm cranial to this. RESULTS: The final study population comprised 78 women. The mean transverse hiatal diameter increased 12.4% between the two examinations, from 39.4 ± 4.1 mm (±standard deviation) at the first examination to 44.3 ± 5.8 mm at the last examination (p < 0.01). We found a moderate correlation between the transverse hiatal diameter and fetal station at the last examination (r = 0.44, r2 = 0.19; p < 0.01; regression equation y = 2.71 + 0.014x), and a weak correlation between the change in transverse hiatal diameter and change in fetal station (r = 0.29; r2 = 0.08; p = 0.01; regression equation y = 0.24 + 0.012x). Levator urethral gap increased significantly in all three planes on both the left and right sides. Head position was not associated with hiatal measurements after adjusting for fetal station. CONCLUSIONS: We found a significant, but only modest, increase of the hiatal dimensions during the first stage of labor. The risk of levator ani trauma will therefore be low during this stage. The change in transverse hiatal diameter was associated with fetal descent but not with head position.

Levator ani muscle avulsion is a risk factor for expulsion within 1 year of vaginal pessary placed for pelvic organ prolapse.

OBJECTIVE: The aim of this study was to investigate whether the presence of levator ani muscle (LAM) avulsion is associated with expulsion within 1 year of a vaginal pessary placed for pelvic organ prolapse (POP). METHODS: This was a prospective observational study of consecutive women with symptomatic POP, who had not received treatment for the condition before the consultation and opted for vaginal pessary placement in our center. Volume acquisition was performed before pessary insertion and offline analysis of the 3D/4D transperineal ultrasound volume data was performed. LAM was assessed on maximum pelvic floor muscle contraction (PFMC) and hiatal dimensions were assessed at rest, on PFMC and on maximum Valsalva. Results were compared between women in whom the pessary was retained for 1 year and those in whom the pessary was expelled within 1 year. RESULTS: The datasets of 255 women were analyzed including 147 (57.6%) women who had a vaginal pessary continuously in place over 1 year and 108 (42.4%) with pessary expulsion. Mean age was 63.2 (SD, 9.9) years and median parity was 3 (2-4). Eighteen (7.1%) had Stage I, 164 (64.3%) Stage II, 67 (26.3%) Stage III and six (2.4%) Stage IV POP. Women with vaginal pessary expulsion within 1 year had significantly larger hiatal dimensions at rest and on Valsalva, larger hiatal area during rest, PFMC and Valsalva and higher rate of LAM avulsion (53.7% vs 27.2%, P < 0.01) compared with women in whom the pessary was retained for 1 year. After controlling for potential confounders, LAM avulsion remained a risk factor (OR, 3.18, P < 0.01) of vaginal pessary expulsion within 1 year. CONCLUSIONS: Women in whom a vaginal pessary was expelled within 1 year of placement for POP had a larger hiatus. Presence of LAM avulsion was associated with a three-fold increase in the risk of expulsion of a vaginal pessary within 1 year. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

The association between vaginal parity and hiatal dimensions: a retrospective observational study in a tertiary urogynaecological centre.

OBJECTIVE: Vaginal childbirth has a substantial effect on pelvic organ supports, which may be mediated by levator ani (LA) avulsion or hiatal overdistension. Although the impact of a first vaginal delivery on the hiatus has been investigated, little is known about the effect of subsequent births. This study was designed to evaluate the association between vaginal parity and hiatal dimension. DESIGN: Retrospective observational study. SETTING: A tertiary urogynaecological unit in Australia. POPULATION: A total of 780 archived data sets of women seen for symptoms of lower urinary tract and pelvic floor dysfunction. METHODS: Standardised in-house interview and assessment using the International Continence Society (ICS) pelvic organ prolapse quantification (POP-Q), and four-dimensional translabial ultrasound. Offline analysis for hiatal dimensions was undertaken blinded to history and clinical examination. MAIN OUTCOME MEASURES: Hiatal area on maximum Valsalva. RESULTS: Of 780 women, 64 were excluded because of missing ultrasound volumes, leaving 716 for analysis: 96% (n = 686) were parous, with a median parity of three (interquartile range, IQR 2-3), and 91.2% (n = 653) were vaginally parous. Levator avulsion was found in 21% (n = 148). The mean hiatal area on Valsalva was 29 cm(2) (SD 9.4 cm(2) ). On one-way anova, vaginal parity was significantly associated with hiatal area (P < 0.001). Most of the effect seems to occur with the first delivery. Subsequent deliveries do not seem to have any significant effect on hiatal dimensions. This remained true after controlling for potential confounding factors using multivariate regression analysis (P = 0.0123). CONCLUSIONS: Vaginal parity was strongly associated with hiatal area on Valsalva. Most of this effect seems to be associated with the first vaginal delivery.

Pelvic floor muscle biometry and pelvic organ mobility in East Asian and Caucasian nulliparae.

OBJECTIVE: To compare the differences in levator ani muscle biometry and hiatal dimensions between pregnant nulliparous Caucasian and East Asian women. METHODS: Offline analysis of three/four-dimensional ultrasound volume data obtained from two groups of pregnant nulliparous women, Caucasian and East Asian, was performed. Volume acquisition was performed in the late third trimester using the same method in both groups, in the context of two prospective observational studies with identical entry criteria. Pelvic organ descent and levator hiatal dimensions were assessed using the volumes acquired on Valsalva maneuver, and pubovisceral muscle thickness was measured from the volumes obtained on pelvic floor muscle contraction (PFMC). RESULTS: Datasets of 200 East Asian and 168 Caucasian women were analyzed. Compared with Caucasian women, East Asian women had a significantly lower body mass index. All indices of pelvic organ descent were significantly higher in the Caucasian group than in the East Asian group. The difference, expressed as a percentage, in levator hiatal area on both Valsalva maneuver and PFMC was markedly greater in Caucasian (32% vs. 19%; P < 0.001) than in East Asian (24% vs. 20%; P = 0.01) women. After controlling for potential confounders using multivariate regression analysis, racial origin remained the only significant factor associated with differences in pelvic organ descent and hiatal dimensions. The thickness and area of pubovisceral muscle were significantly higher in the East Asian group. CONCLUSIONS: Pregnant women of East Asian racial origin have a thicker pubovisceral muscle, smaller hiatus and less mobility of pelvic organs than do pregnant Caucasian women.

Intra- and interobserver reliability of levator ani muscle biometry and avulsion using three-dimensional endovaginal ultrasonography.

OBJECTIVES: To test intra- and interobserver reliability of assessment of levator ani muscle (LAM) biometry and avulsion using antenatal and postnatal three-dimensional (3D) endovaginal ultrasonography (EVUS), and to determine levator-urethra gap (LUG) values on EVUS. METHODS: Primigravid women were scanned prior to delivery, early postpartum and 3 months postpartum, with EVUS performed at rest using a standardized protocol. During post-processing, measurements were taken in the plane of minimal hiatal dimensions by two independent investigators blinded to the clinical information and each other's results. LAM attachment to the pubic bone was assessed at the pubococcygeus and puborectalis levels using a score system: (1) intact; (2) partial avulsion (< 50%); (3) partial avulsion (≥ 50%); and (4) complete avulsion. Intraclass correlation coefficients (ICCs) and limits of agreement (LOAs) were calculated for each time point, with intraobserver analysis conducted in a random sample of 20 women scanned 3 months following delivery. RESULTS: One hundred and sixty-nine antenatal scans, 83 early postpartum scans and 75 scans at 3 months postpartum were performed. The intra- and interobserver ICCs, respectively, were 0.95 and 0.86-0.88 for hiatal area, 0.90 and 0.16-0.74 for hiatal transverse diameter, 0.91 and 0.73-0.80 for hiatal anteroposterior diameter, 0.50 and 0.32-0.52 for LAM thickness at the '9 o'clock position' and 0.55 and 0.33-0.45 for LAM thickness at the '3 o'clock position'. Both intra- and interobserver analysis revealed acceptable LOAs for hiatal measurements, but the LOAs were wide for thickness measurements. The correlation of LAM avulsion score was excellent on intra- and interobserver analysis. Antenatal mean ± SD LUGs were 18.8 ± 2.4 mm and 19.2 ± 2.3 mm on right and left sides, respectively; the intraobserver ICC was 0.82-0.91 but LOAs were wide, while interobserver ICC was 0.13-0.68 and also had wide LOAs. CONCLUSIONS: 3D-EVUS is a reliable tool for the assessment of hiatal measurements and LAM avulsion in women during pregnancy and after delivery, but performs less well for measurements of LAM thickness and LUG. EVUS can therefore be used in research studies involving childbirth and recurrent prolapse.