Introduction
In 1995, Morris first identified a poorly muscular healing scar on the uterine incision, now called the previous cesarean scar defect (CSD), of patients who developed postmenstrual abnormal uterine bleeding(PAUB) after a cesarean section (C-section) (Figure 1A-1C). The incidence of CSD ranges from 50% to 84% in random populations of women with a history of cesarean section1.
Because many scholars consider that reducing the rate of the cesarean section can reduce the occurrence of CSD, CSD has not received widespread attention. However, women with CSD suffer from a series of symptoms, all of which affect the patient’s quality of life. PAUB can affect a couple’s sex life and the couple’s relationship. It can also cause genital tract inflammation, vulva pruritus, and chronic abdominal pain2,3. Additionally, with the implementation of China’s three-child policy, women of childbearing age who have a history of C-section will face subsequent pregnancy, and research has shown that CSD size and the TRM are significantly correlated with subsequent infertility, it also significantly reduces the success rate of frozen embryo transfer4-5. It has also shows that CSD is associated with cesarean scar pregnancy, placenta previa with placenta accreta, and even uterine rupture6,7.
The treatment approaches for CSD are usually divided into durgs and surgery, but there are no treatment guidelines. Drugs mainly include oral contraceptives, which can improve the symptom of PAUB during medication, but it may relapse after stopping drugs8. Common surgical procedures can be broadly categorized as reconstructive surgery and surgery for improved PAUB symptoms. Reconstructive surgical techniques, such as laparoscopic(LP)and vaginal repair(VR), involve isthmocele resection and resuture. Surgery for improving PAUB symptoms, such as hysteroscopic electroresection (HP), HP involves the removal of the fibrous tissue flap from the bottom of the defect and cauterizes the remaining scar tissue by using a wire loop9-11. Hysteroscopic resection surgery can improve PAUB symptoms but will lead to thinning of the myometrial tissue around the CSD, increasing the risk of the subsequent pregnancy12. In patients with severe pelvic adhesions, attempt to repair the CSD through vaginal surgery may be difficult in entering the abdomen, leading to the risk of bladder injury or surgical failure. We use vaginal repair assisted by single-port laparoscopy to reduce the risk of bladder injury (Figure 1D, E, F). Therefore, a good preoperative evaluation can help to formulate a more suitable treatment to improve prognosis. It is particularly important to recognize that not all diverticula require surgery and that not all surgeries can improve the diverticulum.
Our surgical team has treated more than 1500 CSD patients from 17 provinces and cities across China, Australia, and the United States since 2013. More than 1200 cases of CSD through VR have been successfully carried out, and it is the largest CSD treatment cohort known nationally and internationally. Our previous study screened 607 women with a history of C-section by transvaginal ultrasound(TVS) and found that when the mean TRM is more than 5.39 mm, these women without PAUB symptoms (menstrual durations less than 7 days) 14. This TRM size is similar to that of Glavind’s study, whose research shows the TRM of 5.8 mm will be helpful for symptom control post-operatively13. According to this result, we define a menstruation duration of no more than 7 days and a TRM of no less than 5.39 mm after vaginal repair as optimal healing.
Our previous studies indicated that CSD disappeared in 64.52% of CSD patients after VR and that 60.0% of patients reached ≤7 days of menstruation15. However, the factors affected healing were not defined, so a model for predicting the outcome of repair surgery is urgently needed. This study retrospectively analyzed 1015 cases of transvaginal repair of CSD to develop a prediction model for the first time. The findings of this study will be used to form an evidence-based proposal for patient selection.