How long after a cesarean section can I get pregnant? Usually, we make a point of instructing our cesarean section patients on their discharge summary that they should not get pregnant again until 2 years after the operation. In the outpatient clinic, we often come across patients who are pregnant again less than 2 years after cesarean section and ask for abortion or medical abortion because of the fear of uterine rupture in late pregnancy. I remember 6 years ago, a familiar friend, the first child due to primary infertility for many years to do in vitro fertilization, after all the hard work to get pregnant, and ultimately because of the precious child for cesarean section. She was surprised and delighted that she got pregnant 8 months after the operation. She also sought my advice on the retention of the fetus, and I said that if you want this baby very much, you have to take some risks yourself, control your weight during pregnancy, monitor closely, and go to the hospital as soon as possible if you have abdominal pain and other symptoms. This friend was very opinionated and insisted on continuing the pregnancy with twins. She had a safe pregnancy and chose to have another cesarean section at 38 weeks of pregnancy, delivering two healthy babies. The uterine scar was well healed and showed no signs of rupture. For example, Hong Kong treats cesarean section as normal delivery and there is no special restriction on repeat pregnancy. How reliable is ultrasound for measuring uterine scar thickness Both doctors and patients habitually turn to ultrasound to try to get a reliable indicator of uterine scar thickness. I will tell you that ultrasound does not accurately identify the boundary between the lower uterine scar and the myometrium in mid- to late-term pregnancy, and therefore cannot correctly measure the thickness of the scar. Of course some patients will show their obstetrician the ultrasound results and it says that the thickness of the lower uterine scar is 2mm or 3mm, so is it true that the smaller the number the more likely it is to rupture? There is no scientific basis for determining whether there is a risk of rupture based on this result alone, as a few millimeters of error in ultrasound measurement is too easy. What does it depend on whether a scarred uterus will rupture or not? It is the strength of the scar and the tension the scar is under, not the thickness, which is something that prenatal and ultrasound assessments cannot do. What we can do is to pay close attention to the scar incision for any tearing pain and any pressure at the scar, if there is none it is safe. So there is no need to ask the sonographer to measure the scar thickness. Is it true that ultrasound has no diagnostic value for uterine scar thickness anymore, not really. If the patient has symptoms, i.e. pain in the lower part of the uterus, then an ultrasound can be requested. If the ultrasound suggests that there is a continuous interruption of the echoes at the uterine scar, it needs to be treated with caution, suggesting that there is a possibility of incomplete uterine rupture. The doctor will make a comprehensive judgment based on the week of pregnancy, the presence of contractions and the presence of pressure pain at the uterine incision to decide whether a cesarean section is needed. Do I always have to have another cesarean section if I have a second pregnancy after a cesarean section? Not necessarily. What are the circumstances under which a trial of labor is possible? An obstetrician may recommend VBAC (vaginal birth after cesarean section) for a second pregnancy in a patient who is pregnant again, who has been examined for cephalopelvic proportionality, who has had a previous cesarean section with a transverse incision of the lower uterine segment (not an abdominal incision) and no other uterine surgical scar, and who does not have any tenderness over the uterine incisional scar in the current pregnancy. Close monitoring is required during labor and emergency management plans for uterine rupture are in place. The risk of uterine rupture during labor has been reported in the literature to be about 0.52%, and the success rate of their vaginal delivery has been reported to be up to 50-80%. What are the risk factors for uterine rupture? According to the literature, uterine rupture in a second pregnancy with a scarred uterus occurs most often in patients undergoing classical cesarean section (i.e., after uterine corpus cesarean section), after laparoscopic myomectomy, after radiofrequency ablation of uterine fibroids, and after myomectomy of larger uterine fibroids. Keloid uteri with a history of larger myomectomy are more prone to rupture than keloid uteri with a history of cesarean section and should be of clinical concern. The short interval between pregnancies and deliveries, the type of suture used for cesarean delivery (single layer suture), and large fetal weight are also high risk factors. Therefore, there is no clear and effective prediction method to assess the possibility of uterine rupture in a second pregnancy with scarred uterus with a history of cesarean section and myomectomy. Routine ultrasound measurement of lower uterine segment thickness is not recommended to avoid unnecessary clinical confusion. Care should be taken to closely monitor the uterine scar for pain for early management.