The thickness of the uterine scar is determined by the recovery of the uterus. After cesarean section or myomectomy, there is a scar on the uterus, which normally heals gradually after surgery. If the scar heals well, it may reach the thickness of normal uterine muscle, which is 2-3 cm, but if the scar is poorly healed, such as a diverticulum in the scar, the thickness of the scar may decrease, sometimes to a few millimeters. If pregnancy occurs in a scarred uterus, as the pregnancy progresses, the fetus grows and the uterus enlarges, the thickness of the uterine scar becomes progressively thinner, sometimes as little as 0.3 cm in the late stages of pregnancy.