Generally the gestational sac is 20mm or more from the scar, which is considered normal. If you have had uterine surgery or a cesarean section, a scar can form in the uterus. If the fertilized egg is deposited in the scar of the uterus, then this is called a keloid pregnancy, which is a type of ectopic pregnancy. In the case of a pregnancy at the scar, there is a chance that the placenta may implant, and this may result in hemorrhage. Without placenta implantation, placenta praevia may also occur, which is also prone to hemorrhage and may even cause uterine rupture. Therefore, if an ultrasound examination is done in early pregnancy and the gestational sac is found to be more than 20mm away from the scar, the possibility of pregnancy at the scar can be ruled out.