Sonographic assessment of post-cesarean section uterine scar in pregnant women

Purpose: To detect location of uterine cesarean scar in relation to cervix in pregnancies with previous cesarean section (CS) and to compare location between elective and emergent previous CS. Study design: Prospective study, 91 pregnant women with previous low transverse CS. Two groups: previous elective [36 (39.6%)] and emergent CS [55 (60.4%)]. Transvaginal ultrasound was performed between 14 and 16 weeks. Cervical length (CL) and distance between external oss to hypoechogenic line (EO-HL distance), which describes location of cesarean scar, were measured. Surgical incision was considered cervical when EO-HL distance was smaller than CL. Results: Mean CL and EO-HL distance: 45.4 + 7. 0 and 39.0 + 9.4 mm, respectively for all patients. No significant differences were observed in CL (45.9 + 6.2 vs. 45.1 + 8.5 mm; p = not significant [NS]) and EO-HL distance (40.7 + 9.7 vs. 37.9 + 9.1 mm; p = NS) between both groups. Sixty-four cases (70.3%) had cervical scar, eight (8.8%) at the level of the internal oss and 19 (20.9) in the lower uterine segment. No significant difference was observed between both groups regarding location of scar (cervix -72 vs. 67% emergent vs. elective, respectively; p = NS). Conclusion: CS incisions are mostly performed in cervix, in elective as well as in emergent operations.