A nomogram to predict the risk of scar pregnancy after caesarean section

The aim of this study was to identify the high-risk factors for caesarean scar pregnancy (CSP) and establish a nomogram to predict the risk of caesarean scar pregnancy in pregnant women with a history of caesarean section. Among 1273 pregnant women with a history of caesarean section, 70% of the patients (892 patients, training sample) were randomly selected for analysis, and a prediction model was generated. The remaining patients (381 patients, validation sample) were validated for the model. Four high-risk factors for CSP were established, including: parity, number of previous abortions, uterus position, and early vaginal bleeding. The area under the curve of the nomogram for the training set was 0.867 and that for the validation set was 0.881, indicating good performance. Calibration curves for predicting CSP showed good calibrations. Decision curve analyses showed good application prospects for the model. Our results show that our nomogram for predicting CSP risks can be a practical tool to help in the early identification of CSP.Impact StatementWhat is already known on this subject? The high-risk factors for "caesarean scar pregnancy", An simple nomogram could be constructed to predict the risk of the disease through these high-risk factors.What do the results of this study add? This study can quickly predict whether the patient is a high-risk group for uterine scar pregnancy based on the patient's previous pregnancy, early vaginal bleeding and uterine position.What are the implications of these findings for clinical practice and/or further research? Caesarean scar pregnancy was secondary Long-term complications after caesarean section that with a high risk of pregnancy. In this study, we established a nomogram based on the number of cases of CSP and a control group with a history of caesarean section delivery at term, The high-risk factors were assigned a certain risk value in the early stage, if the woman contains more high-risk factors, the higher the risk of developing CSP, it should be highly valued in the early stage, and the rate of visiting a doctor should be increased.