Early postpartum sonographic evaluation of cesarean scar following vaginal birth after cesarean section: a prospective cohort study.

PURPOSE: To evaluate cesarean scar morphology following vaginal birth after cesarean section (VBAC) and to examine associations of scar parameters with labor and clinical parameters.

MATERIALS AND

METHODS

In a prospective cohort study at a single tertiary center, women who had undergone one prior low-transverse cesarean section and delivered vaginally underwent two transvaginal ultrasound examinations: one immediately after delivery and one 24-48 hours postpartum. Scar depth and width, adjacent myometrial thickness (AMT), and residual myometrial thickness (RMT) were measured. Correlations with clinical and labor variables were analyzed.

RESULTS

50 women were included. The mean maternal age was 30.7 ± 4.8 years and the mean BMI was 30.3 ± 4.4 kg/m². 41 women completed both examinations. Between the two ultrasound examinations, the mean scar depth and width decreased (15.8 ± 6.7 mm vs. 13.1 ± 4.1 mm; p = 0.009 and 16.8 ± 9.6 mm vs. 12.2 ± 5.8 mm; p = 0.007, respectively), while the AMT and RMT remained unchanged (p > 0.7). Non-spontaneous labor onset was associated with deeper scars (p = 0.027), and spontaneous rupture of membranes correlated with a greater RMT (p = 0.041). Women with a BMI ≥30 kg/m² had a thinner AMT and RMT (p = 0.022 and 0.025, respectively) and more frequent labor augmentation (p = 0.006). No uterine ruptures or major maternal and neonatal complications occurred.

CONCLUSION

Immediate postpartum ultrasound after VBAC elucidated early remodeling of the previous cesarean scar. Non-spontaneous labor onset and a higher BMI were associated with a less favorable scar morphology, though without adverse short-term maternal or neonatal outcomes.