Patients with a uterine septum usually exhibit decreased fertility, an increased early spontaneous abortion rate, and an increased premature birth rate [7, 8]. The thickness of the uterine mediastinal tissue varies, and the muscle cells are arranged into nodules of different sizes. There are only a few capillaries in the muscle nodules, while the outer layer is distributed with medium-sized blood vessels . Endometrial dysplasia affects embryo implantation, development, placental function and coordination of uterine contraction, leading to adverse pregnancy outcomes.
Frank proposed the feasibility of TCRS as early as 1981 . At present, there are various methods used to treat the uterine septum, such as hysteroscopic cold scissors incision, unipolar or bipolar incision, and laser incision. Nicola Colacurci et al  proposed that there was no difference in reproductive outcomes, including the rate of premature birth or the incidence of spontaneous abortion, after unipolar, bipolar or cold-knife surgery. However, M. Cararach  proposed that cold-knife surgery had a higher pregnancy rate and delivery rate. Berta Esteban Manchado's study reported that the pregnancy rate after laser surgery was 78.9% . The surgical method did not affect the pregnancy outcome, and the purpose was to remove the septum and improve the uterine cavity environment to make the uterine cavity more normal. To the best of our knowledge, there has been no published research evaluating the postsurgical reproductive outcomes of patients with an incomplete versus those with a complete uterine septum. This study showed that the conception rate did not obviously change between the two groups after operation, possibly because the resection of the septum increases the chances of sperm entering the contralateral fallopian tube, significantly increasing the rate of pregnancy. This study concluded that TCRS can significantly reduce the rate of spontaneous abortion and embryo arrest and improve the rate of full-term delivery, consistent with the findings of most studies, and TCRS has greater value for patients with a complete uterine septum.
Some studies indicated that pregnancy after operation of the uterine septum would have a decreased risk of spontaneous abortion ; however, this paper concludes that the rate of threatened abortion (abdominal pain or a small amount of vaginal bleeding) in early pregnancy among patients with a uterine septum increases significantly after operation, but with active treatment, the pregnancy could continue, with most being delivered at full term and few being delivered preterm. The high rate of threatened abortion may be due to the short repair time for the endometrial injury caused by the operation, the lack of recovery of normal function and zygote implantation in the septum. It is not clear whether appropriately prolonging the pregnancy duration after operation would reduce the risk of threatened abortion, so more data need to be collected. Placenta previa in patients with an incomplete uterine septum operation is related mainly to the high rate of spontaneous abortion and embryo arrest, which are caused by multiple uterine operations. If the uterine septum is found by ultrasound because of multiple spontaneous abortions or embryo arrest, the septum can be actively treated to prevent an increase in pregnancy complications such as placental abnormalities and threatened abortion. No significant relationship was found between other comorbidities and whether the uterine septum was operated on.
After TCRS, the rate of cesarean section is increased , but it is not clear how septum resection increases the risk of cesarean section. In this study, abnormal fetal position, placenta previa and fetal distress increased the rate of cesarean section after the operation of incomplete uterine septum. Although these reasons may also lead to an increased rate of cesarean section among patients with a complete uterine septum, other factors affecting the rate of cesarean section (cesarean section without a medical indication) are significantly higher. A complete uterine septum has a low preoperative pregnancy rate and a long postoperative pregnancy interval and is almost combined with a vaginal mediastinum and double cervix, which increases the psychological burden for pregnant women; thus, they choose cesarean section.
The difference between the postoperative uterine septum and other types of scarred uterus is not clear. After surgery, the residual septum may lead to a weaker uterine wall, further stretching during pregnancy and an increased risk of uterine rupture. Second, there are differences between septum histology and myometrium; during labor, the differences destroy uterine polarity, resulting in uterine weakness and increased postpartum bleeding or uterine rupture due to excessive uterine contraction. To avoid related complications during vaginal delivery, which may lead to poor pregnancy outcomes, cesarean section is chosen. Although the complications can be quite serious, the probability of their occurrence appears to be low. Some investigators  reported that there was no case of uterine rupture after the operation. Additionally, Vid Jansa's study showed that only 4 cases were found to have uterine rupture during cesarean section delivery .
Therefore, the high rate of cesarean section among patients with a complete uterine septum is due mainly to associated psychological factors. We can alleviate the fears of pregnant women early on and closely monitor the safety of the mother and child during labor, to prevent an unnecessary cesarean section.
After TCRS, endometrial wound healing reaches 100% within 2 months , but no study has calculated the optimal time for postoperative natural pregnancy. Panagiotis Bakas  reported that the highest pregnancy rate was within 15 months after surgery. A retrospective cohort study by Murat Berkkanoglu et al  found no differences in the pregnancy or miscarriage rates of 282 women who underwent IVF/ICSI at <9, 10–16, or > 17 weeks after surgery. During follow-up, the pregnancy rate of the patients with incomplete uterine septum was highest at the 6th month after surgery, while that of the patients with complete uterine septum was highest at the 12th month after surgery. Complete uterine septum is treated mostly because of associated infertility, although it is combined with the vaginal mediastinum, which does not seem to affect the woman’s sex life. In this study, the longer pregnancy interval after operation may be due to the poor preoperative pregnancy outcome, with the patient refusing to have sex earlier because of her perception that the surgical trauma is high and that a long repair time is needed for complete uterine septum. Second, the conception rate of patients with complete uterine septum is low before operation, but the operation improves the pregnancy rate; however, we do not know the width or depth of the septum into the myometrium, and the lack of clarity on details regarding postoperative recovery of deep tissues may lead to a longer interval from surgery to postoperative pregnancy. Although those studies showed that mediastinal size does not affect the postoperative pregnancy outcomes of patients with incomplete uterine septum , we did not explore this effect in depth in this paper. It is not clear how many weeks there should be between operation of the uterine septum and delivery of the pregnancy. However, in this paper, we recommend that the achieving pregnancy in the 6th month after operation in patients with incomplete uterine septum and in the 12th month after operation in patients with complete uterine septum can increase pregnancy rate and avoid missing the optimal time for pregnancy. There are still adverse pregnancy outcomes, such as abortion and embryo arrest after surgery. Because there are no data on the exact time of abortion after TCRS, this study does not address the relationship between the abortion rate and postoperative pregnancy interval with the goal of avoiding an unintended pregnancy that ends in spontaneous abortion or embryo arrest.
The possible limitations of our series are the relatively small number of patients with a uterine septum, the inability to completely exclude other confounding infertility factors, and the retrospective nature of the study, which may cause some bias. This paper provides clinically useful data to assist and reveal the clinical diagnosis and determine treatment. We plan to conduct a randomized controlled trial in the future to objectively understand the impact of TCRS on reproductive outcomes. More data will be added in the future.