Anatomy of the sonographic post-cesarean uterus.

PURPOSE: We aim to describe the sonographic uterine anatomy after a cesarean section (CS), test the reproducibility of predefined measurements from the BSUM study, and report the distribution of these measurements. METHODS: This is a descriptive observational study where 200 women with a history of only one CS were recruited 12-24 months postoperatively. A 5-13 MHz micro-convex transvaginal transducer was used for the acquisition of volumetric datasets for evaluating the CS scars. We defined 15 distinct measurements including the residual myometrial thickness (RMT). RMT ratio was calculated as a percentage of RMT to the assumed pre-cesarean anterior uterine wall thickness. A P value below 0.05 is utilized for significant statistical analysis. RESULTS: Patients were included on average 18.5 months post-cesarean. The uterus was anteflexed in 82.5% and retroflexed in 17.5%. Myometrial defects at the site of CS manifest in two forms, either as a niche or as fibrosis. Patients are classified into four groups: those with isolated niches (45%), combined niches and fibrosis (38.5%), isolated fibrosis (11%), and lacking both (5%). The median RMT ratio for these groups was 63.09, 40.93, 59.84, and 100% with a standard deviation of 16.73, 12.95, 16.59, and 0, respectively. The interclass correlation coefficient (ICC) remained above 0.9 for all distinct measurements among these groups except for those of RMT, where ICC varied between 0.47 and 0.96. The RMT ratio shows a constant ICC at 0.94 regardless of the group. CONCLUSION: The post-cesarean uterus is often anteflexed, and a myometrial loss of about 50% is normally expected. The pattern of this loss is in the form of a predominantly sharp-edged and echogenic niche, fibrosis, or a combination of both. The proposed RMT ratio takes these changes into consideration and results in a reproducible quantification. We hypothesize that different adverse outcomes could be attributed to the different scar patterns.

Assessing lateral uterine wall defects and residual myometrial thickness after cesarean section.

OBJECTIVE: Lateral wall ruptures in women with a history of cesarean section are less common but more complicated than anterior wall ruptures. Residual myometrial thickness (RMT) is believed to be valuable for assessing the probability of ruptures. This study aimed to assess the utility of OmniView (a sonographic reslicing technique) in evaluating the lateral uterine wall after cesarean section and evaluate the relationship between lateral and anterior wall RMT using OmniView and sagittal two-dimensional ultrasound. STUDY DESIGN: This cross-sectional study examined changes in both the anterior and lateral uterine wall in women with a history of cesarean section in the past 12-18 months. OmniView with volume contrast imaging with a 2-mm slice thickness was used to generate coronal planes, and the OmniView RMT (OV-RMT) was calculated as a percentage. Blinded to the OV-RMT results, sonographic multiplanar views were used to acquire the optimum sagittal plane for evaluating the RMT, and the sagittal RMT (S-RMT) was calculated as a percentage. The reproducibility of OV-RMT and S-RMT between two observers was tested using interclass correlation (ICC). The relationship between two variables was tested using Spearman's rank correlation. RESULTS: In 208 recruited patients, the prevalence of lateral uterine wall defects was 79 %. The interobserver and intraobserver reproducibility of S-RMT and OV-RMT had ICC coefficients over 0.9 with a p-value <0.001. S-RMT and OV-RMT did not follow a normal distribution, and the medians were significantly different (55.5 and 85.7, respectively). Spearman's rank correlation between OV-RMT and S-RMT had a rho (ρ) value of 0.24 (p < 0.05). Passing-Bablok regression had an intercept of 47.95 and a slope of 0.65. CONCLUSION: OmniView can be used to assess lateral uterine wall defects, and OV-RMT is a reproducible and reliable method for quantifying this assessment. The RMT on the coronal plane was independently more intact than that on the sagittal plane, which might account for the lower incidence of lateral ruptures. Further studies could reveal a critical OV-RMT value that is safe for a trial of labor.

Combined treatment of McDonald cerclage and Arabin-pessary: a chance in the prevention of spontaneous preterm birth?

Background: Patients with cervical shortening obtained by transvaginal ultrasound and/or previous preterm delivery are at increased risk for preterm birth in the current pregnancy. The aim of the present cohort study was to compare the rate of preterm birth and early neonatal parameters in patients at risk and screening patients who received either a cerclage or a combined treatment of cerclage and cervical pessary.Methods: A retrospective cohort study was conducted from March 2005 to March 2017 including all patients in our department which received a McDonald cerclage or a combined treatment of McDonald cerclage and an Arabin pessary. A total of 81 women with singleton pregnancies were considered the final sample of this cohort study, of whom 34 patients received a cerclage and 47 patients received a cerclage combined with a pessary. Patients "at risk" with a history of preterm birth at <37 weeks of gestation, late-term abortion, conization, or cervical cerclage in a previous pregnancy because of a cervical shortening <10th percentile and women with no inherent historic risk factors but a current cervical length <3rd percentile (screening group) were analyzed separately. We defined delivery <34 weeks of gestation as the primary outcome. Secondary outcomes were preterm birth (PTB) <28, <32, and <37 weeks of gestation, admission to the neonatal intensive care unit (NICU), neonatal admission time, birthweight, and prolongation of the gestation.Results: There were no differences between the two study groups with regard to baseline characteristics. Delivery <34 weeks of gestation occurred in 32.4 and 27.7% of patients treated with cerclage versus combined treatment respectively (p = .48). Similarly, there was no difference in the rate of preterm birth at <28, <32, or <37 weeks of gestation. The mean neonatal admission time at the neonatal intensive care unit was shorter in the combined treatment group versus in the cerclage group (p = .02). There was a trend for higher birthweight (2368 g ± 962 vs. 2650 g ± 1063) in favor of the combined treatment arm (p = .077).Conclusion: The combined treatment of cerclage with an Arabin pessary seems to be a considerable alternative in the prevention of spontaneous PTB (sPTB), especially for patients with cervical length <3rd percentile, and in particular for patients with amnion prolapse in terms of birthweight and neonatal admission time.