Measurement Of Lower Uterine Segment Research Articles

Predicting Uterine Rupture Risk Using Lower Uterine Segment Measurement During Pregnancy With Cesarean History: How Reliable Is It? A Review

Predicting Uterine Rupture Risk Using Lower Uterine Segment Measurement During Pregnancy With Cesarean History: How Reliable Is It? A Review

Predicting Uterine Rupture Risk Using Lower Uterine Segment Measurement During Pregnancy With Cesarean History: How Reliable Is It? A Review

Predicting Uterine Rupture Risk Using Lower Uterine Segment Measurement During Pregnancy With Cesarean History: How Reliable Is It? A Review

Accuracy of sonographic lower segment thickness and prediction of vaginal birth after caesarean in a resourced-limited setting; Prospective study.

To assess the accuracy of ultrasound measurement of the lower uterine segment (LUS) thickness against findings at laparotomy, and to investigate its correlation with the success rate of vaginal birth after one previous caesarean delivery (CD) in a resource-limited setting. Prospective study. Obstetrics and Gynaecology department in a tertiary hospital in Ghana. Women with one previous CD undergoing either a trial of labour (TOLAC) or elective CD. Myometrial lower uterine segment thickness (mLUS) and full lower uterine segment thickness (fLUS) were measured with transvaginal ultrasound (TVUS). The women were managed according to local protocols with the clinicians blinded to the ultrasound measurements. The LUS was measured intraoperatively for comparison with ultrasound measurements. Lower uterine segment findings at laparotomy, successful vaginal birth. A total of 311 pregnant women with one previous CD were enrolled; 147 women underwent elective CD and 164 women underwent a TOLAC. Of the women that underwent TOLAC, 96 (58.5%) women had a successful vaginal birth. The mLUS was comparable to the intraoperative measurement in the elective CD group with LUS thickness <5 mm (bias of 0.01, 95% CI -0.10 to 0.12 mm) whereas fLUS overestimated LUS <5 mm (bias of 0.93, 95% CI 0.80-1.06 mm). Successful vaginal birth rate correlated with increasing mLUS values (odds ratio 1.30, 95% CI 1.03-1.64). Twelve cases of uterine defect were recorded. LUS measurement ≤2.0 mm was associated with an increased risk of uterine defects with a sensitivity of 91.7% (95% CI 61.5-99.8%) and specificity of 81.8% (95% CI 75.8-86.8%). Accurate TVUS measurement of the LUS is technically feasible in a resource-limited setting. This approach could help in making safer decisions on mode of birth in limited-resource settings.

Ultrasound Assessment of Cesarean Section Scar and its Correlation to Intraoperative Scar Status

Background and Aim: In the past decades the rate of cesarean sections has increased enormously, there are many indications for cesarean section like placenta previa, labor dystocia, presumed fetal distress, fetal malpresentation, multiple gestation, and suspected fetal macrosomia, but the commonest reason for performing a cesarean is a previous cesarean birth .The present study aimed to compare the sonographically measured lower uterine scar with actual status of scar at the time of operation. Methodology: The descriptive cross-sectional study was conducted on 150 female patients who presented to Obstetrics department of Creek general hospital, affiliated with UMDC from August 2021 to January 2022. The Inclusion Criteria was: females with singleton pregnancy with history of previous single caesarian section, vertex presentation and gestational age 36-40 weeks. While women with multiple gestations, placenta previa, polyhydramnios or any uterine abnormality were excluded. Results: The overall mean of age, gestational age, parity and fetal weight were 28.22±4.59 years, 37.60±0.78 weeks, 1.73±0.94 and 2.75± 0.47 kg respectively. Significant association was observed between lower uterine segment measurements by Sonographic scar thickness during pregnancy and intra-operative scar findings at the time of delivery (p-value&lt; 0.05). Conclusion: The present study found that sonographically measured lower uterine scar thickness is a solid predictor for scar defect in women with previous cesarean section. As a result, we can conclude that sonographic measurement of lower uterine segment thickness is a reliable tool for assessing scar status and deciding which women should be given a vaginal delivery trial. Keywords: Previous Caesarean Section, Lower uterine scar, Sonography

Ultrasonographic assessment of lower uterine segment thickness and perinatal Outcomes in patients with a previous cesarean history

Objective: The purpose of the study was to establish the validity of the abdominal evaluation of lower uterine segment (LUS) thickness in patients having a previous cesarean section (CS) in predicting uterine rupture, and to evaluate if there is any effect of the number of a previous surgeries on adverse maternal and perinatal outcomes.&#x0D; Materials and methods: A prospective case-control study was carried out between December 2017 and June 2018 in Dr. Zekai Tahir Burak Women’s Health Education and Research Hospital. 555 patients were classified into three groups; Group 1: patients having one previous CS, Group 2: patients having two previous CS, Group 3: patients having more than the two previous CS). Ultrasonographic measurements of the LUS, intraoperative findings and, adverse pregnancy outcomes were assessed.&#x0D; Results: LUS thickness of group 2 was significantly less than the LUS thickness of the other groups (p=0.022). The feeling of pain was significantly more in the patients of group 2, when compared with the other groups (p=0.019). Pregnancy interval was the only parameter that had significant predictivity for adverse pregnancy outcomes for group 1(#CS=2) and group 3 (#CS≥4) (p=0.042, and p=0.021, respectively). In group 2 (#CS=3), age, the thickness of LUS, and thickness of subcutaneous adipose tissue were found to have significantly high predictivity for adverse pregnancy outcomes (p=0.012, p≤0.001, and p=0.007, respectively).&#x0D; Conclusion: Measurement of LUS, in the patients who had previous CS, can be used for risk assessment and management. It is a non-invasive, reliable and, easily applicable method. Standardization of the measurement technique is a necessity.

VP46.23: Comparison of the lower uterine segment measurements, performed by expert and resident in pregnant women with and without previous Caesarean section

VP46.23: Comparison of the lower uterine segment measurements, performed by expert and resident in pregnant women with and without previous Caesarean section

Does Lower Uterine Segment Thickness Measurement Improve Birth Planning After Previous Cesarean Section?

Lower uterine segment (LUS) thickness measurement is frequently used to select patients for trial of labor after a previous cesarean section (TOLAC). To date no significant benefit of LUS measurement has ever been proven, and no standard protocol or clear cut-off value exists. The aim of this study was to evaluate the benefit of LUS measurement in a daily routine setting. In this retrospective study, we evaluated 631 pregnancies after previous cesarean section (CS). Ultrasound measurements of myometrial (mLUS) and/or full LUS (fLUS) thickness were performed in 399 (63%) patients. The incidence, time, and mode of detection of uterine defects were studied. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated for different cut-off values of LUS thickness. Uterine defects were diagnosed in 28 (4.4%) patients. Detection rate of ultrasound was low (13.6%), with better sensitivity, specificity, PPV, and NPV at lower (2 mm (fLUS) / 1 mm (mLUS): 75/96/48.3/98.7%) than at higher cut-off values (3 mm (fLUS) / 2 mm (mLUS): 15.8/93.2/10.4/68.7%). The benefit of LUS thickness measurement appears overestimated. As a large number of methodological factors trigger inaccuracy, a consistent protocol including both a transabdominal and a transvaginal scan performed by a trained examiner might improve accuracy. Exclusion of uterine defects might be more useful for prenatal selection after CS.

Prédiction échographique du risque de rupture utérine après césarienne : LUSTrial, un essai randomisé pragmatique

BackgroundThe data from literature show that trial of labor and elective repeat cesarean delivery after a prior cesarean delivery both present significant risks and benefits, and these risks and benefits differ for the woman and her fetus. The benefits to the woman can be at the expense of her fetus and vice-versa. This uncertainty is compounded by the scarcity of high-level evidence that preclude accurate quantification of the risks and benefits that could help provide a fair counseling about a trial of labor and elective repeat cesarean delivery. An interesting way of research is to evaluate the potential benefits of a decision rule associated to the ultrasound measurement of the lower uterine segment (LUS). Indeed, ultrasonography may be helpful in determining a specific risk for a given patient by measuring the thickness of the LUS, i,e, the thickness of the cesarean delivery scar area. Although only small and often methodologically biased data have been published, they look promising as their results are concordant: ultrasonographic measurements of the LUS thickness is highly correlated with the intraoperative findings at cesarean delivery. Furthermore, the thinner the LUS becomes on ultrasound, the higher the likelihood of a defect in the LUS. Finally, ultrasound assessment of LUS has an excellent negative predictive value for the risk of uterine defect. Therefore, this exam associated with a rule of decision could help to reduce the rate of elective repeat cesarean delivery and especially to reduce the fetal and maternal mortality and morbidity related to trial of labor after a prior cesarean delivery. Methods/designThis is a pragmatic open multicenter randomized trial with two parallel arms. Randomization will be centralized and computerized. Since blindness is impossible, an adjudication committee will evaluate the components of the primary composite outcome in order to avoid evaluation bias. An interim analysis will be planned mid-strength of the trial. Ultrasound will be performed by expert sonographers after certification by the main investigator. Women aged 18 years or older are eligible for this trial if they have a singleton pregnancy in cephalic presentation at a gestational age from 36 to 38 weeks, a previous low transverse cesarean delivery and sign the informed consent sheet. Women will be asked to participate in this study when they reach a term of 36 to 38 weeks of gestation. After agreement, women will be randomized into two groups: in the study group, they will have the LUS measured by ultrasound and the patient will be informed that, based on a threshold value of 3.5mm for the ultrasound measurement of the LUS thickness, the patient with a higher measurement will be considered at low risk and will be encouraged to choose a trial of labor whereas the patient with a measurement is equal to or less than this threshold will be considered at risk and encouraged to choose an elective repeat cesarean; in the control group, ultrasound LUS measurement will not be performed. The mode of delivery will be decided according to standard practice at the center. The primary composite outcome will include: uterine rupture, uterine dehiscence, hysterectomy, thromboembolic complications, transfusion, endometritis, maternal mortality, fetal prenatal and intrapartum mortality, hypoxic-ischemic encephalopathy and neonatal mortality. DiscussionThis trial assesses the efficacy of ultrasound measurement of the lower uterine segment in women with a prior cesarean delivery in reducing fetal and maternal morbidity and mortality and it will provide evidence in order to establish clinical recommendations. Trial registrationClinicalTrials.gov identifier: NCT01916044 (date of registration: 5 August 2013).

Measurements of the Lower Uterine Segment at Term in Women with Previous Cesarean Delivery

Purpose: To evaluate the accuracy of sonographic measurements of the lower uterine segment (LUS) thickness at term in predicting uterine scar defects in women with previous Cesarean delivery (CD). Methods: Eighty-nine pregnant women who underwent CD between 37 and 41 weeks of gestation from 2013 to 2015 were enrolled in this study and divided into two groups. Group A consisted of women with previous CD, and Group B consisted of women with previous vaginal deliveries. We performed an ultrasound evaluation of the myometrial and full thickness of LUS (mLUS and fLUS) transvaginally before a CD and evaluated the appearance of LUS during surgery, which was defined as follows: grade I, well-developed; grade II, thin without visible content; grade III, translucent with visible content; and grade IV, either dehiscence or rupture. Results: The median mLUS and fLUS were 1.50 and 4.07 mm in the group A, and 2.75 and 5.37 mm in the group B. We observed significant differences in the median mLUS and fLUS between grades I/II (2.07 and 4.37 mm) and grades III/IV (0.67 and 2.52 mm). Both mLUS and fLUS were predictive factors for grades III/IV and cutoff values were 0.97 mm of mLUS and 3.13 mm of fLUS, having a sensitivity of 87.5% and 75.0%, and a specificity of 87.7% and 91.4% in mLUS and fLUS measurement, respectively. Conclusion: Sonographic measurements of LUS at term may be a feasible and reliable method to predict uterine rupture or uterine dehiscence in women with prior CD.

Transvaginal Ultrasonographic Measurement of Lower Uterine Segment in Term Pregnant Patients with Previous Cesarean Section

Background: With an aim to reduce the rates of repeat cesarean section in women with a previous scar, prediction of scar rupture or dehiscence is important. If we could predict the risk of rupture by measuring the scar thickness closer to term, we could pursue a trial of scar safely. Aims: To evaluate the use of ultrasound measured thickness of lower uterine segment as one of the predictors of scar rupture or dehiscence in labour and establish a cut off beyond which trial of labour can be attempted safely. Methodology: 187 randomly selected pregnant women with history of one previous cesarean section in the past who satisfied the inclusion criteria, attending the outpatient clinic over a period of six months, at a tertiary level teaching institution in southern India were selected and counseled to undergo a transvaginal measurement of the scar region. These women were then followed up until delivery and the outcome of trial of scar, successful vaginal delivery, rupture or dehiscence of uterus was analysed in relation to the scar thickness and various other contributing factors. Results: 187 women with history of previous cesarean section, attending the outpatient clinic were randomly chosen to undergo trans vaginal scan at term. 52 underwent elective cesarean section and 135 went through trial of scar. The median cut-off of the lower uterine segment in this study population of 135 was 2.4 mm. The sensitivity was 90.9%, specificity was 43.5%, positive predictive value was 12.5%, and negative predictive value was 98.3% at this cut-off for scar rupture or dehiscence. Conclusions: The lower uterine scar thickness could be a useful tool to predict scar rupture. This could aid in making decisions regarding induction of labour with oxytocin in women with previous cesarean section.

Sonographic prediction of scar dehiscence in women with previous cesarean section.

To estimate the risk of uterine dehiscence/rupture in women with previous cesarean section (CS) by comparing the thickness of lower uterine segment (LUS) and myometrium with trans-abdominal (TAS) and trans-vaginal sonography (TVS). In this case-control study, in 100 pregnant women posted for elective CS (with or without previous CS; group 1 and group 2 respectively), the thickness of LUS and myometrium was measured sonographically (TAS and TVS). Intra-operatively, LUS was graded (grades I-IV), and its thickness was measured with calipers. The primary outcome of the study was correlation between echographic measurements (TAS and TVS) and features of LUS (grades I-IV) at the time of CS. Secondary outcomes were correlation between myometrial thickness, number of previous CS, and inter-delivery interval with LUS (grades I-IV). Sonographic measurements of LUS and myometrium were significantly different between the two groups (both TAS and TVS p value=0.000 each). However, the number of previous CS (p=0.440) and inter-delivery interval (p=0.062) had no statistically significant correlation with thickness of LUS. Sonographic evaluation of LUS scar and myometrial thickness (both with TAS and TVS) is a safe, reliable, and non-invasive method for predicting the risk of scar dehiscence/rupture. Specific guidelines for TOLAC, after sonographic assessment of women with previous CS, are need of the hour.

Variables influencing the integrity of lower uterine segment in post-cesarean pregnancy.

There is significant increase in proportion of cases with previous cesarean delivery requiring obstetric care. The available literature fails to provide uniform opinion on each woman's characteristics to identify risk of uterine rupture while planning trial of labor after cesarean. To study the association of abnormal lower uterine segment with some of the present and previous obstetric variables including patient characteristics and surgical techniques at previous cesarean operation. Consenting consecutive 96 post-cesarean singleton pregnancies admitting after 36 weeks gestation at the same facility from July 2011 to December 2012 for repeat cesarean, were studied. Only the cases with cephalic presentation and vertex as presenting part, having no placenta previa, polyhydramnios, uterine anomaly or fibroid and those who had previous one lower segment cesarean were recruited. Based on the intra-operative finding the lower uterine segment (LUS) was categorized into those having a normal and abnormal (grades 2-4) LUS. Sonographic assessment of LUS thickness and any abnormalities if any were noted. The findings of abnormal LUS (direct observation at surgery and sonographic impression within a week before surgery) were looked for association with some of the present and previous obstetric variables including patient characteristics and surgical techniques at previous cesarean operation using Student t, Chi square or Fisher's exact test for analysis as appropriate. Receiver operating curve analysis was used to determine the optimal cut off value for prediction of LUS integrity by ultrasound. Of the women recruited for the study, 36 were admitted in early labor and ultrasound evaluation of LUS was performed in 48 of the remaining 60 women admitted antenatal for elective cesarean delivery. There were 38 abnormal LUS (39.6%) with 22 of them (57.9%) graded as 'thinned out LUS'. The incidence of scar dehiscence (grade 3, cases 5) was 5.2% of 96 cases and there were no cases of scar rupture. Proportion of cases with abnormal LUS was significantly high when primary cesarean was done in preterm (p = 0.02); it was a single layer uterine closure (p = 0.02), and inter-cesarean interval was 54 months (p = 0.01). Abnormal LUS was also seen to be associated with maternal age beyond 35 years (p = 0.2), when cesarean was performed in labor (p = 0.5), following 18 h of rupture of membranes (p = 0.75), for a baby weight more than 3 kg (p = 0.4), and different suture materials (polyglactin 910 and chromic catgut) were used to close uterus at primary cesarean delivery (p = 0.1), and also if they had post-partum fever (p = 0.3). Ultrasound measurement of LUS by abdominal scan correlated with the intra-operative LUS grading and a thickness of more than 3.2 mm within a week before delivery and was seen to be the safe cut off above which most of the women had a normal LUS (sensitivity 92.3%, specificity 81.1%). Factors at primary cesarean operation significantly influence the state of LUS at term in subsequent pregnancy .

Sonographic Measurement of Lower Uterine Segment Thickness to Predict Uterine Rupture During a Trial of Labor in Women With Previous Cesarean Section

Along with the increasing rate of cesarean section (CS) births has been a concomitant decrease in the rate of vaginal birth after cesarean (VBAC), mostly due to concerns about uterine rupture during a trial of labor (TOL). The risk of uterine rupture in laboring women with a previous CS must be balanced against the increasing current and future risk of peripartum hysterectomy with repeat cesarean. Improved prediction of uterine rupture could allow women at low risk to have a TOL, and those at high risk for uterine rupture could undergo a planned CS. Thinning in the lower uterine segment (LUS) measured by ultrasonography is a possible predictor of uterine rupture. The present study was performed to identify an optimal LUS thickness cutoff value and to define groups of women with a history of previous CS to whom TOL either should not be offered or could be offered safely. PubMed and EMBASE were searched for relevant articles published during 1980 to 2011. Included studies reported on pregnant women with at least 1 prior CS and on the sonographic appearance of the LUS during pregnancy in relation to uterine defects observed during or immediately after delivery. Studies were scored on methodologic and clinical characteristics. For each study, a 2 x 2 table was constructed, cross-classifying LUS thickness measured by ultrasound and the presence of LUS defect after delivery. Sensitivity and specificity were determined for each study in the receiver operating characteristic (ROC) space along with a corresponding summary ROC curve. From an initial 147 citations, 21 studies (all cohort design) were included and involved 2776 women. The median sample size was 71 (range, 10-642; interquartile range, 149.5). Lower uterine segment measurements were obtained at 34 to 39 weeks' gestation. Cutoff values used to define an insufficient LUS ranged from 0.5 to 3.0 mm in studies measuring myometrial LUS thickness and from 1.5 to 5.1 mm in those using full LUS thickness. Full LUS thickness measurement using cutoffs of 2.0 to 3.0 mm had a specificity of 0.91 (95% confidence interval [CI], 0.80-0.96) at a sensitivity of 0.61 (95% CI, 0.42-0.77). Full LUS thickness measurement using cutoffs of 3.1 to 5.1 mm had a specificity of 0.63 (95% CI, 0.30-0.87) at a sensitivity of 0.96 (95% CI, 0.89-0.98). The accuracy of transvaginal or transabdominal sonography could not be compared statistically because of the limited number of studies. The main finding is the strong negative correlation between LUS thickness and risk of uterine defect. The similar shapes of the ROC curves for myometrial and full LUS thickness indicated no significant difference in accuracy, shape, and position. An ideal screening test to predict uterine rupture could affect medical decision making by allowing accurate selection of women with a scarred uterus unlikely to have uterine rupture and thus able to have a TOL

Sonographic measurement of lower uterine segment thickness to predict uterine rupture during a trial of labor in women with previous Cesarean section: a meta‐analysis

To evaluate the accuracy of antenatal sonographic measurement of lower uterine segment (LUS) thickness in the prediction of risk of uterine rupture during a trial of labor (TOL) in women with a previous Cesarean section (CS). PubMed and EMBASE were searched to identify articles published on the subject of sonographic LUS measurement and occurrence of a uterine defect after delivery. Four independent researchers performed identification of papers and data extraction. Selected studies were scored on methodological quality, and sensitivity and specificity of measurement of LUS thickness in the prediction of a uterine defect were calculated. We performed bivariate meta-analysis to estimate summary receiver-operating characteristics (sROC) curves. We included 21 studies with a total of 2776 analyzed patients. The quality of included studies was good, although comparison was difficult because of heterogeneity. The estimated sROC curves showed that measurement of LUS thickness seems promising in the prediction of occurrence of uterine defects (dehiscence and rupture) in the uterine wall. The pooled sensitivity and specificity of myometrial LUS thickness for cut-offs between 0.6 and 2.0 mm was 0.76 (95% CI, 0.60-0.87) and 0.92 (95% CI, 0.82-0.97); cut-offs between 2.1 and 4.0 mm reached a sensitivity and specificity of 0.94 (95% CI, 0.81-0.98) and 0.64 (95% CI, 0.26-0.90). The pooled sensitivity and specificity of full LUS thickness for cut-offs between 2.0 and 3.0 mm was 0.61 (95% CI, 0.42-0.77) and 0.91 (95% CI, 0.80-0.96); cut-offs between 3.1 and 5.1 mm reached a sensitivity and specificity of 0.96 (95% CI, 0.89-0.98) and 0.63 (95% CI, 0.30-0.87). This meta-analysis provides support for the use of antenatal LUS measurements in the prediction of a uterine defect during TOL. Clinical applicability should be assessed in prospective observational studies using a standardized method of measurement.

Visibility and measurement of Cesarean section scars in pregnancy: a reproducibility study

To evaluate the visibility of cesarean section (CS) scars by transvaginal sonography (TVS) in pregnant women, to apply a standardized approach for measuring CS scars and to test its reproducibility throughout the course of pregnancy. In this observational cohort study, 320 consecutive pregnant women with a previous cesarean delivery were examined to assess scar visibility by two independent examiners. TVS was carried out at 11-13, 19-21 and 34-36 weeks' gestation. A scar was defined as visible when an area of hypoechogenicity representing myometrial discontinuity at the anterior wall of the lower uterine segment was identified. In a subset of patients (n = 111), visible scars were measured by two independent examiners in three dimensions: scar width, depth and length as well as the residual myometrial thickness (RMT). Descriptive analysis was used to assess scar visibility, and the intraclass correlation coefficient (ICC) was calculated to show the strength of absolute agreement between two examiners for scar measurements. For RMT, a cut-off of 2.4 mm was used and measurement agreement was assessed using Cohen's kappa coefficient. The scar was visible in 284/320 cases (88.8%). Visible scars were significantly associated with anteverted uteri (P < 0.0001). Both examiners had 100% agreement on scar visibility at 12 and 20 weeks' gestation, while agreement was 96% at 34 weeks. The intra- and interobserver agreements for scar measurements were generally good (ICC 0.86 and 0.89, respectively). The kappa coefficient for the RMT was 0.27 in the first trimester, compared with 0.51 and 0.72 in the second and third trimesters, respectively. CS scars remain visible in the majority of women throughout pregnancy. They can be reproducibly measured in three dimensions when assessed by TVS in all trimesters of pregnancy. The agreement between two observers for CS scar measurement can be considered good for the first trimester, compared with relatively moderate agreement for the second and third trimesters.

Pitfall in Ultrasound Evaluation of Uterine Scar from Prior Preterm Cesarean Section

We report two cases of women with a previous cesarean performed before active labor at 29 weeks of gestation who underwent sonographic measurement of the lower uterine segment (LUS) at 36 weeks' gestation in their subsequent pregnancy. In both cases, uterine scar defect was detected on the upper part of the LUS, at ∼9 to 11 cm from the cervical os, and was only visualized by the transabdominal approach. We suggest that early gestational age and the absence of labor at previous cesarean can lead to a higher uterine scar location on the LUS and, therefore, increase the risk of uterine rupture in subsequent pregnancy. The heterogeneity of uterine scar location could explain discrepancies observed in studies using the transabdominal versus the transvaginal approach or both regarding the predictive value of LUS measurements for uterine rupture.

2D versus 3D transabdominal sonography for the measurement of lower uterine segment thickness in women with previous cesarean delivery

Objective To evaluate the intermethod reliability of using 3D versus 2D transabdominal sonography in the measurement of lower uterine segment (LUS) thickness in women with previous cesarean delivery, in addition to determining the interobserver reliability of 2D and 3D transabdominal sonography in LUS measurement. Methods Between February and July 2010 at Queen Mary Hospital, Hong Kong, 40 pregnant women with a history of previous cesarean delivery at 36–39 weeks of pregnancy underwent LUS measurement via 2D and 3D transabdominal sonography by 2 observers. The 3D examination was performed on the multiplanar display of the longitudinally acquired LUS volume. Inner myometrial thickness (MT) and full thickness (FT) were measured at the thinnest portion and perpendicular to the contour of the LUS. Results The 2D and 3D LUS measurements obtained by the 2 observers were comparable (intraclass correlation coefficient [ICC]: MT, 0.81 and 0.98, respectively; FT, 0.76 and 0.98, respectively). For transabdominal LUS measurement, 2D MT provided the best interobserver reliability (ICC: 2D MT, 0.95; 2D FT, 0.91; 3D MT, 0.82; 3D FT, 0.77). Conclusion Compared with the 2D approach, 3D transabdominal sonography does not seem to improve the reliability of LUS measurement. 2D measurement of MT seems to be most reliable between different observers.

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.

Lower uterine segment thickness measurement in pregnant women with previous Cesarean section: reliability analysis using two‐ and three‐dimensional transabdominal and transvaginal ultrasound

To evaluate the reliability of two- and three-dimensional ultrasonographic measurement of the thickness of the lower uterine segment (LUS) in pregnant women by transvaginal and transabdominal approaches. This was a study of 30 pregnant women who had had at least one previous Cesarean section and were between 36 and 39 weeks' gestation, with singleton pregnancies in cephalic presentation. Sonographic examinations were performed by two observers using both 4-7-MHz transabdominal and 5-8-MHz transvaginal volumetric probes. LUS measurements were performed using two- and three-dimensional ultrasound, evaluating the entire LUS thickness transabdominally and the LUS muscular thickness transvaginally. Each observer measured the LUS four times by each method. Reliability was analyzed by comparing the mean of the absolute differences, the intraclass correlation coefficients, the 95% limits of agreement and the proportion of differences < 1 mm. Transvaginal ultrasound provided greater reliability in LUS measurements than did transabdominal ultrasound. The use of three-dimensional ultrasound improved significantly the reliability of the LUS muscular thickness measurement obtained transvaginally. Ultrasonographic measurement of the LUS muscular thickness transvaginally appears more reliable than does that of the entire LUS thickness transabdominally. The use of three-dimensional ultrasound should be considered to improve measurement reliability.

Sonographic Measurement of the Lower Uterine Segment Thickness in Women With Previous Caesarean Section

Objectives: To evaluate the accuracy of prenatal sonography in determining the lower uterine segment (LUS) thickness in women with previous Caesarean section and to assess the usefulness of measuring LUS thickness in predicting the risk of uterine rupture during a trial of vaginal birth.Methods: Sonographic examination was performed in 102 pregnant women with one or more previous Caesarean sections at between 36 and 38 weeks’ gestation to assess the LUS thickness, which was defined as the shortest distance between the urinary bladder wall-myometrium interface and the myometrium/chorioamniotic membrane-amniotic fluid interface. Of the 102 women examined, 91 (89.2%) had transabdominal sonography only, and 11 (10.8%) had both transabdominal and transvaginal examinations. The sonographic measurements were correlated with the delivery outcome and the intraoperative LUS appearance.Results: The mean sonographic LUS thickness was 1.8 mm, standard deviation (SD) 1.1 mm. An intraoperatively diagnosed paper-thin or dehisced LUS, when compared with an LUS of normal thickness, had a significantly smaller sonographic LUS measurement (0.9 mm, SD 0.5 mm, vs. 2.0 mm, SD 0.8 mm, respectively; P < 0.0001). Two women had uterine dehiscence, both of whom had prenatal LUS thickness of < 1 mm. Thirty-two women (31.4%) had a successful vaginal delivery, with a mean LUS thickness of 1.9 mm, SD 1.5 mm; none had clinical uterine rupture. A sonographic LUS thickness of ≤ 1.5 mm had a sensitivity of 88.9%, a specificity of 59.5%, a positive predictive value of 32.0%, and a negative predictive value of 96.2% in predicting a paper-thin or dehisced LUS.Conclusions: Sonography permits accurate assessment of the LUS thickness in women with previous Caesarean section and therefore can potentially be used to predict the risk of uterine rupture during trial of vaginal birth.