First and Third Trimester Uterine Scar Thickness in Women With Previous Caesarean: A Prospective Comparative Study.

BACKGROUND: Lower uterine segment (LUS) thickness in the third trimester of gestation is associated with the risk of uterine scar defect at delivery. It was suggested that first trimester residual myometrial thickness (RMT) could also predict uterine scar defect at delivery. OBJECTIVE: This study sought to correlate the RMT measured at the site of uterine scar in the first trimester with the LUS thickness measured in the third trimester. METHODS: This was a prospective cohort study of women with a singleton pregnancy and a single prior low-transverse CS. All participants underwent an evaluation of uterine scar by using transvaginal ultrasound at 11 to 13 weeks, including the presence of a scar defect and measurement of RMT; and a second evaluation at 35 to 38 weeks, combining both transvaginal and transabdominal ultrasound, for the measurement of LUS thickness. Spearman's correlation test was used to compare first and third trimester measurements. RESULTS: A total of 166 eligible participants were recruited at mean GA of 12.7 ± 0.5 weeks. We observed an absence of correlation between first trimester RMT and third trimester LUS thickness (correlation coefficient 0.10; P = 0.20). First trimester RMTs below 2.0 mm and below 2.85 mm are poor predictors of third trimester LUS thickness below 2.0 mm (sensitivity, 8% and 23%; specificity, 98% and 87%; positive predictive value, 25% and 14%, respectively). CONCLUSION: There is a poor correlation between first trimester RMT and third trimester LUS thickness in women with a previous CS. First trimester RMT should not be used to inform women on their risk of uterine rupture or to guide clinical management.

First-trimester placental thickness and the risk of preeclampsia or SGA.

INTRODUCTION: Placental thickness in the second trimester of pregnancy has been associated with risks of placenta-mediated complications of pregnancy. We aimed to estimate the association between first-trimester maximum placental thickness and the subsequent risk of preeclampsia and/or the delivery of small-for-gestational-age (SGA) neonate. METHODS: Prospective cohort study of women recruited at 11-14 weeks gestation. Placental thickness was measured at its apparent center and reported in multiple of median (MoM) adjusted for gestational age. Participants were followed until delivery for pregnancy outcomes. Placental measurements of participants who developed preeclampsia and/or delivered SGA neonate (defined as birth weight below 10th percentile) were compared with those who did not using non-parametric statistical analyses. RESULTS: We recruited 991 participants at a mean gestational age of 12.7 ± 0.7 weeks of gestation. SGA (n = 52) was associated with reduced 1st trimester placental thickness (median: 0.89 MoM; interquartile (IQ): 0.75-1.02 vs 0.98 MoM; IQ: 0.84-1.15; p < 0.01). Pregnancies that developed preeclampsia (n = 20) tended to have greater placental thickness (median: 1.10 MoM; IQ: 0.93-1.25 vs 0.97 MoM; IQ: 0.84-1.14; p = 0.06) with values > 1.2 MoM significantly increasing the risk for preeclampsia (relative risk: 3.6; 95%CI: 1.5-8.6, p < 0.01). Pregnancies complicated by both SGA and preeclampsia (n = 5) had similar placental thickness in the first-trimester in comparison with uncomplicated pregnancies (median: 1.03 MoM; IQ: 0.89-1.42 vs 0.98 MoM; IQ: 0.84-1.14; p = 0.33). CONCLUSION: First-trimester placental thickness diverges in pregnancies at risk of preeclampsia (increased) or SGA (decreased), but remains within normal values in pregnancies at risk of both conditions, suggesting that the underlying pathologies have some opposing effects on early placental growth. The current findings should be validated in a larger cohort.

Reliability of First-Trimester Ultrasonic Biopsy for the Evaluation of Placental and Myometrial Blood Perfusion and the Prediction of Preeclampsia.

OBJECTIVE: Low placental vascularization measured by three-dimensional (3-D) ultrasound with power Doppler can predict preeclampsia. We evaluated the reliability and reproducibility of the ultrasonic sphere biopsy (USSB) technique to evaluate placental and subplacental myometrium vascularization in the first trimester. METHODS: We performed a secondary analysis of a case-control study nested in a prospective cohort of women with a singleton pregnancy undergoing ultrasound at 11 to 14 weeks' gestation. Women who developed preeclampsia (n = 20) and randomly selected controls (n = 60) were compared. Other controls (n = 60) were also randomly selected to evaluate intra- and inter-observer reproducibility. Using 3-D power Doppler, the vascularization index (VI), flow index (FI), and vascularization flow index (VFI) were measured from the volume of the whole placenta and the subplacental myometrium and from their respective USSB. Pearson's correlation coefficients (cc) with their P-values were calculated. RESULTS: We observed that USSB is reliable in estimating the vascularization of the whole placenta in the first trimester (cc of VI 0.83; of FI 0.62; and of VFI 0.78; P < 0.001 for all) but was not as reliable for estimating subplacental myometrium vascularization (cc of VI 0.71; of FI 0.35; and of VFI 0.73). Measurement of placental vascularization using USSB showed good to excellent intra- and inter-observer reproducibility (cc of VI 0.86 and 0.85, respectively; of FI 0.75 and 0.75, respectively; and of VFI 0.83 and 0.83, respectively; P < 0.001 for all). Finally, we observed that women who subsequently developed preeclampsia had lower placental USSB VI (2.1 vs 4.8, P = 0.02), FI (32.4 vs. 42.5, P = 0.002), and VFI (0.8 vs. 2.1, P = 0.01) than controls. CONCLUSION: First-trimester USSB of the placenta using 3-D power Doppler is a reliable and reproducible procedure for estimating placental vascularization and could be used to predict preeclampsia.

Impact of uterine closure on residual myometrial thickness after cesarean: a randomized controlled trial.

BACKGROUND: Incomplete healing of uterine scar after cesarean has been associated with adverse gynecological and obstetrical outcomes. Several studies reported that uterine closure at cesarean influences the healing of uterine scar and the risk of uterine rupture at subsequent pregnancies: the commonly used locked single-layer suture including the decidua being associated with a 4-fold increased risk of uterine rupture. However, data from randomized trials are lacking. OBJECTIVE: We sought to evaluate the impact of 3 techniques of uterine closure after cesarean delivery on uterine scar healing. STUDY DESIGN: This was a 3-arm 1:1:1 randomized study in women with singleton pregnancies undergoing elective primary cesarean delivery at ≥38 weeks' gestation. Closure of the uterine scar was carried out by locked single layer including the decidua, double layer with locked first layer including the decidua, or double layer with unlocked first layer excluding the decidua. Primary outcome was residual myometrial thickness (RMT) at the site of the scar, measured by transvaginal ultrasound 6 months after delivery. Secondary outcome was the RMT as a percentage of the myometrial thickness above the scar (healing ratio). Intent-to-treat analyses using Student t test were performed to compare each double-layer technique to the single-layer closure, and P < .025 was considered significant. RESULTS: Complete follow-up was obtained from 73 (90%) of the 81 participants. Compared to single-layer closure, double-layer closure with unlocked first layer was associated with thicker RMT (3.8 ± 1.6 mm vs 6.1 ± 2.2 mm; P < .001) and greater healing ratio (54 ± 20% vs 73 ± 23%; P = .004). In contrast, double-layer closure with locked first layer was not significantly different than single-layer closure in either RMT (4.8 ± 1.3; P = .032) or healing ratio (60 ± 21%; P = .287). CONCLUSION: Double-layer closure with unlocked first layer is associated with better uterine scar healing than locked single layer.