First-trimester uterine scar assessment by transvaginal ultrasound.

Abstract

The objective of the study was to describe the assessment of lower segment uterine scar (LSCS) by transvaginal ultrasound (TVUS) during a first-trimester scan. Patients with a history of LSCS were prospectively enrolled over a 6 month period. Four groups were defined: type 1A, thin scar within cervicoisthmic canal (CIC); type 1B, thin above the internal os (IO); type 2A, dehiscent within the CIC; type 2B, dehiscent above the IO. Accuracy of first-trimester TVUS was investigated by blind testing a panel of 14 operators over a web-based dataset. The scar was visualized in 122 of 123 patients enrolled. Types 1A, 1B, 2A, and 2B occurred in 49.2%, 3.3%, 38.3%, and 9.2%, respectively. When blind tested, fetal medicine specialists achieved a median sensitivity of 82% and specificity of 100% for the detection of a scar. These were 83% and 87% for nonspecialists. First-trimester uterine scar assessment may become a valuable tool in early recognition of patients at risk of subsequent perinatal complications.