Aim: To compare smooth muscle cells, type I collagen, and apoptosis of the lower uterine segment of women who had/without a prior cesarean delivery.
Methods: Alpha smooth muscle actin (α-SMA), type I collagen, and nuclear apoptosis were compared between the groups from lower uterine segment. Twenty-eight controls and 82 with one prior cesarean delivery were included. The women with a prior cesarean section were classified by time since the surgery: ≤3 years, >3 and ≤5 years, >5 and ≤7 years, >7 and ≤9 years, and >9 years.
Results: Smooth muscle volume density (VD) % was significantly lower in women who had cesarean sections in first three groups than in the controls (all, P<0.01). Type I collagen VD% was similar among all groups and the controls. The number of apoptotic nuclei in the lower uterine segment of the scarred group was greater up to 3 years after surgery and less than in the control at 7-9 years. The number of non-apoptotic nuclei in the scarred group was greater than controls up to 7 years after surgery.
Conclusion: The lower uterine segment scar becomes stable at 3 years after cesarean delivery, and by 9 years, the scar is mature.
Keywords: Cesarean; collagen; scar; smooth muscle; uterus.