In classical caesarean section more chances of rupture of uterus is in:
Upper uterine segment is at more risk of rupture in case of a previous classical cesarean section. Here incision is made on the anterior uterine wall in the upper segment above the reflection of uterovesical fold of peritoneum. It is because such a scar is difficult to appose and healing is not good because of frequent contractions and retraction during puerperium. (Sheila TB of obstetrics 2nd edtn pg 338)
Upper uterine segment
Lower uterine segment
Uterocervical junction
posterior uterine segment
Abnormal labor