Comparative accuracy of magnetic resonance morphometry and sonography in assessment of post-cesarean uterine scar

Gayatri Satpathy, Ishan Kumar, Manjari Matah, Ashish Verma, Gayatri Satpathy, Ishan Kumar, Manjari Matah, Ashish Verma

Abstract

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.

Keywords: Lower segment caesarian section; magnetic resonance imaging; scar thickness; uterine scar; vaginal birth after cesarean.

Conflict of interest statement

There are no conflicts of interest.

Figures

Figure 1
Figure 1
Longitudinal sonographic image showing measurement of scar thickness taken at the thinnest portion of the lower uterine segment
Figure 2
Figure 2
T2-weighted mid-sagittal image showing hyperintense scar and thickness measured at its thinnest portion
Figure 3
Figure 3
Bland–Altman plot of the difference between the scar thickness measurements obtained by USG and MRI against the mean values of scar thickness derived from these two methods
Figure 4( A-C )
Figure 4(A-C)
Receiver–operating characteristics (ROC) curves evaluate individual utility of USG (A), MRI (B) and comparison of both (C) in predicting surgical grade 3 scar
Figure 5
Figure 5
Comparison between sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracies between USG and MRI based on cut-off values determined from ROC curve

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Source: PubMed

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