Normand Brassard

Fetal Health Surveillance: Antepartum and Intrapartum Consensus Guideline

OBJECTIVE This guideline provides new recommendations pertaining to the application and documentation of fetal surveillance in the antepartum and intrapartum period that will decrease the incidence of birth asphyxia while maintaining the lowest possible rate of obstetrical intervention. Pregnancies with and without risk factors for adverse perinatal outcomes are considered. This guideline presents an alternative classification system for antenatal fetal non-stress testing and intrapartum electronic fetal surveillance to what has been used previously. This guideline is intended for use by all health professionals who provide antepartum and intrapartum care in Canada. OPTIONS Consideration has been given to all methods of fetal surveillance currently available in Canada. OUTCOMES Short- and long-term outcomes that may indicate the presence of birth asphyxia were considered. The associated rates of operative and other labour interventions were also considered. EVIDENCE A comprehensive review of randomized controlled trials published between January 1996 and March 2007 was undertaken, and MEDLINE and the Cochrane Database were used to search the literature for all new studies on fetal surveillance both antepartum and intrapartum. The level of evidence has been determined using the criteria and classifications of the Canadian Task Force on Preventive Health Care. SPONSOR This consensus guideline was jointly developed by the Society of Obstetricians and Gynaecologists of Canada and the British Columbia Perinatal Health Program (formerly the British Columbia Reproductive Care Program or BCRCP) and was partly supported by an unrestricted educational grant from the British Columbia Perinatal Health Program.

Single- versus double-layer closure of the hysterotomy incision during cesarean delivery and risk of uterine rupture

To evaluate the best available evidence regarding the association between single‐layer closure and uterine rupture.

Lower uterine segment thickness to prevent uterine rupture and adverse perinatal outcomes: a multicenter prospective study

BACKGROUND Choice of delivery route after previous cesarean delivery can be difficult because both trial of labor after cesarean delivery and elective repeat cesarean delivery are associated with risks. The major risk that is associated with trial of labor after cesarean delivery is uterine rupture that requires emergency laparotomy. OBJECTIVE This study aimed to estimate the occurrence of uterine rupture during trial of labor after cesarean delivery when lower uterine segment thickness measurement is included in the decision-making process about the route of delivery. STUDY DESIGN In 4 tertiary-care centers, we prospectively recruited women between 34 and 38 weeks of gestation who were contemplating a vaginal birth after a previous single low-transverse cesarean delivery. Lower uterine segment thickness was measured by ultrasound imaging and integrated in the decision of delivery route. According to lower uterine segment thickness, women were classified in 3 risk categories for uterine rupture: high risk (<2.0 mm), intermediate risk (2.0-2.4 mm), and low risk (≥2.5 mm). Our primary outcome was symptomatic uterine rupture, which was defined as requiring urgent laparotomy. We calculated that 942 women who were undergoing a trial of labor after cesarean delivery should be included to be able to show a risk of uterine rupture <0.8%. RESULTS We recruited 1856 women, of whom 1849 (99%) had a complete follow-up data. Lower uterine segment thickness was <2.0 mm in 194 women (11%), 2.0-2.4 mm in 217 women (12%), and ≥2.5 mm in 1438 women (78%). Rate of trial of labor was 9%, 42%, and 61% in the 3 categories, respectively (P<.0001). Of 984 trials of labor, there were no symptomatic uterine ruptures, which is a rate that was lower than the 0.8% expected rate (P=.0001). CONCLUSION The inclusion of lower uterine segment thickness measurement in the decision of the route of delivery allows a low risk of uterine rupture during trial of labor after cesarean delivery.

Comparing Rates of Trial of Labour Attempts, VBAC Success, and Fetal and Maternal Complications Among Family Physicians and Obstetricians

OBJECTIVES To determine differences between family physicians and obstetricians in rates of trial of labour (TOL) attempt, vaginal birth after Caesarean section (VBAC) success, and maternal-fetal complications. METHODS We undertook a database evaluation study in an urban Quebec secondary care hospital centre that serves a multiethnic population. Study subjects were pregnant women with at least one previous Caesarean section (CS), who delivered singletons at St. Marys Hospital Center between January 1995 and December 2003. Outcomes were rates of TOL attempt, of VBAC success and failure, and of uterine rupture or dehiscence. RESULTS Of 32 500 singleton deliveries, 3694 (11.4%) women met study criteria. Of these, 3493 (94.6%) were patients of obstetricians, and 201 (5.4%) were patients of family physicians. The TOL attempt rate was 50.6% (1768) and 81.1% (163) for obstetricians and family physicians, respectively (P 0.001). For women having TOL, the VBAC success rate was 64.3% for obstetricians and 76.1% for family physicians (P = 0.002). Rates of uterine rupture or dehiscence in the combined failed and successful VBAC groups were 2.9% for obstetricians and 4.3% for family physicians (P = 0.33) whereas in the failed VBAC group the rates were 7.9% versus 17.9% for the family physicians (P = 0.04). Within delivery outcomes for successful and failed VBAC there were no differences in maternal characteristics and newborn outcomes by physician group. CONCLUSION More patients of family physicians than of obstetricians attempted TOL and had successful VBAC. Newborn outcomes were similar in the two groups, except that in the failed VBAC group, the family doctors had slightly higher uterine rupture or dehiscence rates; given the low power of this study, further studies are needed to confirm and explain this result. Also, given the similarity in patient profiles, the differences in delivery outcomes may be attributable to differences in physician practice styles.

Reliability of Two-Dimensional Transvaginal Sonographic Measurement of Lower Uterine Segment Thickness Using Video Sequences

OBJECTIVES To report the intra- and interobserver reliability of measurement of the lower uterine segment (LUS) thickness using transvaginal sonographic videos. METHODS A prospective study of 60 women with previous, low-transverse cesarean undergoing LUS examination (36 to 39 weeks) was performed. Two observers independently measured full LUS thickness using transvaginal sonography. A video of the LUS was recorded and analyzed more than 2 months later by both observers. Intra- and interobserver reliability was assessed with median absolute differences and interquartile range (IQR), nonparametric limits of agreement, intraclass correlation coefficients (ICC) with 95% confidence interval (95% CI), and kappa coefficients. RESULTS Median full LUS thickness was 3.6 mm (range: 0.9 to 8.0 mm). Intraobserver repeatability was excellent (median difference: 0.2 mm, IQR: 0.1 to 0.4; ICC: 0.94, 95% CI: 0.90 to 0.96; kappa: 1.00). Interobserver (median difference: 0.3 mm, IQR: 0.2 to 1.3; ICC: 0.91, 95% CI: 0.86 to 0.95; kappa: 0.76, 95% CI: 0.54 to 0.98) and intermethod reproducibility (median difference: 0.4 mm, IQR: 0.2 to 0.8; ICC: 0.82, 95% CI: 0.72 to 0.89; kappa: 0.69, 95% CI: 0.43 to 0.94) were good. However, both interobserver and intermethod reproducibility were improved when LUS thickness was below 3 mm. CONCLUSION Full LUS thickness measured from transvaginal sonographic videos has excellent intra- and interobserver reproducibility and good reproducibility with live transvaginal ultrasound.

Reliability of 3-Dimensional Transvaginal Sonographic Measurement of Lower Uterine Segment Thickness

The purpose of this study was to report the intraobserver and interobserver reliability of transvaginal 3‐dimensional (3D) sonographic measurement of lower uterine segment thickness.

Mesure du segment inférieur utérin : sommes-nous prêts pour une application clinique ?

The measurement of the lower uterine segment (LUS) seems to be the best technique available to estimate the risk of uterine rupture, but there is a great heterogeneity in the techniques used. It appears necessary to standardize the interventions and their teaching prior to extending the use of the LUS measurement to clinical settings beyond well-defined research purposes.

OP15.09: A standardized method of LUS measurement in late pregnancy

using a transvaginal approach with a full bladder. Third, we found a significant difference in full LUS between the two approaches (McNemar test, p < 0.05) with a difference greater than 1mm in 35% of the cases and greater than 0.5 mm in 50% of the cases. Finally, the quality of the images were superior with the transvaginal approach in all cases. Conclusion: There is a high reproducibility between transvaginal and transabdominal approach for the identification of the thinnest area of LUS when it is evaluated with a full bladder. However we found only a moderate correlation for the measurements of the full LUS between the two approaches. While we agree that both should be performed, our data and the literature strongly suggest that transvaginal approach is mandatory for the most precise measurement and is likely the optimal approach in the evaluation of LUS for women with prior Cesarean contemplating a vaginal birth.

OP15.08: Comparison between transvaginal and abdominal sonography of lower uterine segment thickness near term

(UtR), and estimate the fraction of CO distributed to the uteroplacental circulation during the second half of pregnancy. Methods: Fifty-three low risk-pregnancies were evaluated longitudinally at approximately 4-weekly intervals from 22 weeks until term (a total of 253 observations). Mean arterial blood pressure (MAP), CO and SVR were measured using impedance cardiography, and the uterine artery blood flow velocities and diameter using Doppler and B-mode ultrasonography, respectively. Quta of both uterine arteries was estimated as the product of time-averaged intensity weighted mean velocity and cross-sectional area of the uterine artery. UtR was calculated as: MAP/sum of right and left Quta. Results: CO increased from 5.5 to 5.8 L/min (p = 0.006) despite a significant increase in SVR from 1046 to 1135 dyne s cm-5 (p = 0.0077) during 22–40 weeks. The UtR decreased from 0.26 to 0.13 mmHg/mL/min (p < 0.00001) and the total utero-placental blood flow more than doubled during the same period increasing from 299 ml/min to 673 ml/min which represented 5.6% to 11.7% of the maternal CO. Conclusion: We have established longitudinal reference intervals for the fraction of maternal CO distributed to the utero-placental circulation at 22–40 weeks of gestation. Increments in uteroplacental blood flow are relatively higher than that of the CO in the second half of pregnancy suggesting redistribution of maternal circulation due to continuous reduction in UtR.

OP21.03: Inter-acquisition reliability of 11–13 weeks sub-placental myometrium vasculature obtained by 3D ultrasound

Mean CRL was 63.03 ± 8.30 mm. Mean gestational age was 12.55 ± 0.63 weeks. Fetal placental sites and ratios were as following; Anterior location 48.1%, Posterior location 40.9%, Lateral location 5.4% and fundal location 3.6%. Left and right uterine artery PI values according to placental sites are shown in the Table 1. There were no statistical significant differences among placental sites. Unilateral or bilateral uterine artery notch was present in 350 pregnant women (19%). Uterine artery notch laterality ratios according to placental sites are as following; in anterior location (n = 168) 65% bilateral, 24% left sided, 11% right sided; in posterior (n = 122) 68% bilateral, 18% left sided, 13% right sided; in lateral (n = 39) 62% bilateral, 28% left sided, 10% right sided and in fundus (n = 21) 58% bilateral, 28% left sided, 14% right sided. The ratios did not show significant difference. Conclusions: The placental site does not seem to have effect on uterine artery PI values and the laterality of uterine artery notch.