Comparison of four imaging modalities for cesarean scar defect: a retrospective study

BACKGROUND AND AIMS: We compared four imaging methods: transvaginal ultrasound(TVU), magnetic resonance imaging(MRI), saline contrast-enhanced MRI (SCE_MRI) and hysteroscopy combined with transabdominal ultrasound (HSC_TAU) for evaluating cesarean scar defect(CSD) morphology and clinical correlations. METHODS: Sixty-one women with prior cesarean delivery and prolonged menstrual bleeding underwent all four imaging modalities within days 7-14 of a single menstrual cycle. We measured CSD length, width, depth, and residual myometrial thickness (TRM), and compared detection rates and severity classification, and the linear regression between CSD length and menstrual bleeding duration. RESULTS: HSC_TAU detected CSD in 100% of patients, compared to 94% for TVU, 97% for MRI, and 97% for SCE_MRI. HSC_TAU measured longer CSD length (median 15.4 mm) than TVU (6.5 mm), MRI (8.0 mm), and SCE_MRI (8.2 mm) (P < 0.001). TVU measured thicker TRM (median 2.7 mm) than HSC_TAU (2.0 mm), MRI (2.0 mm), and SCE_MRI (1.8 mm) (P < 0.001). Using TRM < 2.5 mm as the threshold for severe CSD, TVU identified only 43% of cases as severe, while HSC_TAU, MRI, and SCE_MRI identified 66-77%. The linear regression analysis revealed a significant association between HSC_TAU-measured CSD length and menstrual bleeding duration (regression coefficient β = 0.24, 95% CI: 0.08-0.30, R² = 0.14, p = 0.003). CONCLUSION: HSC_TAU offers high detection rate and reliable TRM measurement. TVU tends to underestimate CSD size and overestimate TRM, which may lead to underdiagnosis of severe cases. We suggest using TVU for initial screening and HSC_TAU for preoperative evaluation in symptomatic patients.