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
