Article

Sonographic lower uterine segment thickness and risk of uterine scar defect: a systematic review

Department of Obstetrics and Gynaecology, Centre Hospitalier Universitaire Sainte-Justine, Faculty of Medicine, Université de Montréal, Montreal QC.
Journal of obstetrics and gynaecology Canada: JOGC = Journal d'obstetrique et gynecologie du Canada: JOGC 04/2010; 32(4):321-7.
Source: PubMed

ABSTRACT To study the diagnostic accuracy of sonographic measurements of the lower uterine segment (LUS) thickness near term in predicting uterine scar defects in women with prior Caesarean section (CS).
PubMed, Embase, and Cochrane Library (1965-2009).
Studies of populations of women with previous low transverse CS who underwent third-trimester evaluation of LUS thickness were selected. We retrieved articles in which number of patients, sensitivity, and specificity to predict a uterine scar defect were available.
Twelve eligible studies including 1834 women were identified. Uterine scar defect was reported in a total of 121 cases (6.6%). Seven studies examined the full LUS thickness only, four examined the myometrial layer specifically, and one examined both measurements. Weighted mean differences in LUS thickness and associated 95% confidence intervals between women with and without uterine scar defect were calculated. Summary receiver operating characteristic (SROC) analysis and summary diagnostic odds ratios (DOR) were used to evaluate and compare the area under the curve (AUC) and the association between LUS thickness and uterine scar defect. Women with a uterine scar defect had thinner full LUS and thinner myometrial layer (weighted mean difference of 0.98 mm; 95% CI 0.37 to 1.59, P = 0.002; and 1.13 mm; 95% CI 0.32 to 1.94 mm, P = 0.006, respectively). SROC analysis showed a stronger association between full LUS thickness and uterine scar defect (AUC: 0.84 +/- 0.03, P < 0.001) than between myometrial layer and scar defect (AUC: 0.75 +/- 0.05, P < 0.01). The optimal cut-off value varied from 2.0 to 3.5 mm for full LUS thickness and from 1.4 to 2.0 for myometrial layer.
Sonographic LUS thickness is a strong predictor for uterine scar defect in women with prior Caesarean section. However, because of the heterogeneity of the studies we analyzed, no ideal cut-off value can yet be recommended, which underlines the need for more standardized measurement techniques in future studies.

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    • "Asakura et al., in 2000 used 1.6mm as the muscular layer cut of value(they measured the muscular layer only) and deduced a 77.8% sensitivity, 88.6% specificity, 22.6% positive predictive value [17] . Jastrow et al., in 2010, in their systematic review of literature have shown that there is stronger correlation between transabdominal full LUS thickness and finding of uterine scar defect (AUC: 0.84 +/-0.03, P < 0.001) than between myometrial layer and scar defect (AUC: 0.75 +/- 0.05, P < 0.01). "
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    ABSTRACT: Objective: to investigate the accuracy of 2D and 3D ultrasound in measurement of Cesarean section (CS) scar thickness. Study design: A prospective observational study conducted on 75 pregnant women with previous 1 or 2 CS candidates for elective CS. Evaluation of LUS using 2D and 3D transabdominal and transvaginal ultrasound is then correlated to scar integrity assessed intraoperatively. Results: Five cases had scar dehiscence with incidence of 6.67%. Dehiscence showed a statistically significant difference between women with previous 2 CS and those with previous 1 CS (4 vs. 1 respectively). The best cutoff value for 2D and 3D transabdominal ultrasound was 3.8 and 5.0 mm, with AUC of 0.737and 0.824, yielding a sensitivity of 60% and 100%, specificity of 91.4% and 62.86% respectively .The best cutoff value for 2D and 3D transvaginal ultrasound was 2.0 and 1.9 mm with AUC of 0.931 and 0.974 with sensitivity of 100% and 100%, specificity of 65.71% and 87.14% respectively. Conclusion: ultrasound is a reliable method for measuring the LUS thickness and scar integrity in patients with previous CS. The use of transvaginal 3D ultrasound in measuring the muscular layer thickness of LUS is the most reliable route with high sensitivity and specificity. To cite this article: Ahmed M Maged et al. 2D and 3D ultrasound assessment of cesarean section scars and its correlation to intraoperative findings.
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    • "Sonographic measurement of the lower uterine segment thickness is a strong predictor for uterine scar defect in women with prior Caesarean section [10]. However, the results of studies are inconsistent and no cut-off value of the uterine scar thickness can be recommended [11]. Only a few sonographic studies provide measurements of the uterus soon after CS [12-14]. "
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    ABSTRACT: Objective The aim of the study was to compare the integrity of the uterine scar after elective and urgent Caesarean section (CS) and specify a technique to describe the sonographic findings. Methods Ultrasound examination was performed in 131 women at 48 and 96 hours (transabdominal), and 6 weeks (transvaginal) after CS. We assessed numerous clinical and ultrasound variables. To quantify the severity of the scar defect, we describe a “dehiscence risk coefficient” (DRC). Results Mean myometrial thickness above the scar and below the scar 6 weeks after CS was 12.1 ± 2.5 mm and 11.5 ± 2.5 mm, respectively. The mean scar thickness after elective and urgent CS was 7.68 ± 2.27 mm and 4.9 mm ± 2.21 mm, respectively. The cut-off value (5th percentile) for the CS scar thickness and for DRC was 2.9 mm and 0.25, respectively. DRC less than 0.25 was elected to consider a severe scar defect, which was diagnosed in 14/131 (10.7%) patients, 1.5% after elective CS and 9.2% after urgent CS. (P < 0.001). Conclusions Dehiscence risk coefficient measurement six weeks after delivery allows for precise quantitative description of the CS scar. Urgent CS has a higher risk for a severe scar defect.
    Central European Journal of Medicine 04/2012; 7(2):235-240. DOI:10.2478/s11536-011-0134-x · 0.21 Impact Factor
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    • "It has been suggested that diagnosis of dehiscence of the lower uterine segment (LUS) by ultrasonography using 2 mm wall thickness as a cut-off was found to have a sensitivity of 100% and a specifi city of 83%, and pre-selecting women with a uterine scar thickness Ͼ 2 mm for a VBAC may prove to be one way forward (Suzuki et al. 2000; Locatelli et al. 2004). Other researchers showed the optimal cut-off value to vary from 2.0 to 3.5 mm for full LUS thickness and from 1.4 to 2.0 mm for the myometrial layer (Jastrow et al. 2010). However, because of the heterogeneity of the analysed studies, no ideal cut-off value can yet be recommended , which underlines the need for more standardised measurement techniques in future studies. "
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    ABSTRACT: The aim of this study was to determine the outcome of labour induction following a previous caesarean section. A total of 43 cases were identified; 23 out of those (53.5%) achieved vaginal delivery. The remaining 20 cases (46.5%) had a repeat caesarean. A total of 25 women had ≥ 1 previous vaginal deliveries and in the remaining 18, the previous caesarean was the only pregnancy carried before the current pregnancy. Out of the 23 women who successfully delivered vaginally, 16 cases (69.6%) had a history of ≥ 1 previous vaginal delivery, while no such history was reported in the remaining seven cases (30.4%). The indications for a repeat caesarean were failed induction of labour in five cases (25%); fetal distress in seven cases (35%); failure-to-progress in eight cases (40%). Only one case (2.3%) of uterine rupture was reported. In conclusion, labour induction following a previous caesarean section is an effective and safe intervention. Vaginal delivery can be anticipated in the majority of these women. This study emphasises the need for thorough counselling of these women regarding benefits and risks of induction of labour, and also highlights the necessity of shared patient-doctor decision-making.
    Journal of Obstetrics and Gynaecology 02/2012; 32(2):141-4. DOI:10.3109/01443615.2011.637143 · 0.60 Impact Factor
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