Background Post-Caesarean uterine scar rupture during vaginal birth after Caesarean section (VBAC) is a potentially life-threatening complication. Prediction of scar dehiscence and scar rupture is vital in treatment planning and selecting candidates of trial of labor after a Caesarean section (CS). Purpose To assess the accuracy of magnetic resonance imaging (MRI) for evaluation of post-Caesarean uterine scar and to predict scar dehiscence during repeat CS. Material and Methods Thirty patients with a history of at least one previous CS underwent pelvic MRI for assessment of uterine scar during a subsequent gestation, all of whom underwent lower segment Caesarean section (LSCS) subsequently due to one of the established indications of CSs. Thickness, T1, T2 signal intensity ratio (SER), and apparent diffusion coefficient (ADC) value of scar site were charted. The lower uterine segment was assessed and graded intraoperatively and findings were correlated with MRI findings. Results A total of 30 participants were included in this study, of which nine were classified as having an abnormal scar (of various grades) based on surgical observations. T2 SER with a cutoff value of 0.935 showed the highest sensitivity of 100% and scar thickness value of 3.45 mm showed highest specificity of 91% in prediction of abnormal scar. On drawing a receiver operating characteristic (ROC) curve, T2 signal intensity ratio showed the highest area under the curve (AUC) closely followed by scar thickness values. Conclusion MRI derived parameters may be utilized for differentiation of an abnormal post-Caesarean uterine scar from a normal one. Both scar thickness and T2 SER measured on MRI can be used to predict scar dehiscence. However, T2 SER can serve as a more standardized and objective criterion.

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Objective:To compare the diagnostic accuracy of magnetic resonance imaging (MRI) with that of ultrasonography (USG) for the measurement of lower segment cesarean scar during trial of labor after cesarean (TOLAC).Materials and Methods:This was a prospective case-control observational study conducted with a cohort of 30 participants being considered for TOLAC but eventually proceeding to lower segment cesarean section (LSCS) at a university-based teaching institute over a period of 2 years. Measurement of scar thicknesses were done by MRI and USG preoperatively and validated by surgical findings. Comparison of diagnostic accuracy as well as the cut-off values (to differentiate a normal scar from an abnormal scar) was done between the two modalities.Results:Insignificant systematic error between the measurements obtained by the two modalities was noted by a Bland–Altmann analysis. The diagnostic accuracy of USG for differentiating a normal from an abnormal uterine scar was 96.7% while that of MRI was at a slightly lower level of 90%. A strong level of agreement between the two modalities was observed.Conclusion:MRI offers no advantage in diagnostic accuracy for the measurement of LSCS scar thickness during consideration of TOLAC.Advances in Knowledge:Measurement of uterine scar by MRI has a good correlation with that done on USG in the setting of post-cesarean pregnancy. The results hold good both for normal (grades 1 and 2) and abnormal (grades 3) scars. MRI, however, does not offer any added advantage over sonographic scar thickness measurement for the differentiation of a normal (grades 1 and 2) from an abnormal (grade 3) scar.