Changes in the Uterine Scar during the First Year after a Caesarean Section: A Prospective Longitudinal Study.

Aim: To study changes in a ceasarean section (CS) scar during the first year after a CS using gel installation sonography (GIS). Methods: Proof-of-concept study, prospective cohort study. Twenty women who delivered by their first CS were evaluated by both transvaginal sonography and GIS 2 months and 1 year after CS. A niche was defined as an anechogenic space at the uterine caesarean scar with a depth >2 mm. The primary outcome was any change in the thickness of the residual myometrium (RMT) as evaluated by GIS. Results: Mean RMT changed in time from 11.9 mm at 2 months to 6.5 mm at 12 months after the CS (p < 0.001). Niche prevalence did not change. The adjacent myometrium (AM) reduced from 15 to 12.4 mm (p = 0.04). The ratio between RMT and AM with GIS decreased from 0.80 at 2 months to 0.54 at 12 months (p = 0.002). Conclusion: RMT thickness, the adjacent myometium and the ratio between the RMT and AM reduces from 2 to 12 months after a CS. The prevalence did not change. This needs to be taken into account when deciding on the timing of niche measurement and the interpretation of the RMT. (C) 2017 S. Karger AG, Basel