Development Of A Risk Assessment Model For Cesarean Scar Pregnancy And Follow-Up Analysis Of The Reproductive Outcomes

ObjectiveCesarean scar pregnancy(CSP)is an ectopic pregnancy of special site,which is one of the long-term complications of cesarean section.If the diagnosis is delayed or misdiagnosed,it may lead to complications such as placental implantation,uterine rupture and massive bleeding,and in severe cases,hysterectomy or even life-threatening events.Therefore,early and precise identification of risk factors of cesarean scar pregnancy and timely preventive and curative measures are essential for the improvement of prognosis and the protection of fertility in patients with CSP.The purpose of this paper is to explore the clinical characteristics of CSP patients,identify high-risk factors,establish a risk prediction model of cesarean scar pregnancy,and follow up and analyze the reproductive outcomes,to be able to identify high-risk patients in an early stage and improve their prognosis.Methods1.Data acquisitionThe data of patients with cesarean scar pregnancy admitted to Changhai Hospital of Naval Medical University from January 1,2012 to December 31,2021 were analyzed retrospectively.87 patients with cesarean scar pregnancy were screened according to the inclusion criteria and exclusion criteria.A total of 174 non-CSP pregnant women with a history of cesarean section admitted in the same period were randomly selected as the control group in a ratio of 1:2.The relevant clinical data were collected through the electronic medical record system of our hospital,including age,body mass index,uterine position,gravidity times,parity times,cesarean section times,abortion times,previous history of CSP,interval between CSP and the last cesarean section,hospital grade,timing of cesarean section,and indications of cesarean section et al.2.Statistical analysisThe statistical software SPSS 26.0 and R-4.2.0 were applied to analyze the data.Chisquare test,t-test or non-parametric test were used to describe the difference of clinical characteristics and clinical variables.Variables with P < 0.05 in the univariate analysis were included in the multivariate Logistic regression model.The stepwise regression method was used to screen the factors of the risk assessment model for cesarean scar pregnancy.The Nomogram was validated internally using Bootstrap validation with 1000 repetitions of computer sampling,and additional clinical data of 60 patients were collected for external validation of the model.The Receiver Operating Characteristic Curve(ROC Curve),the Calibration Curve and Decision Curve Analysis(DCA)were used to assess the accuracy,consistency and clinical usefulness of the model.Results1.The case group included 87 cases.The median duration of menopause was 49(44,59)days.26(29.9%)patients with CSP had vaginal bleeding,3(3.4%)had abdominal pain,22(25.3%)had abdominal pain with vaginal bleeding,18(20.7%)were asymptomatic,and18(20.7%)were admitted to hospital due to failure of primary treatment.56(64.4%)patients with type I CSP,21(24.1%)with type II,and 10(11.5%)with type III CSP were included.All patients were treated.Five cases(5.7%)were treated with intramuscular MTX.41 cases(47.1%)underwent negative pressure aspiration under ultrasound guidance.37 cases(42.5%)underwent abdominal uterine scar site pregnancy lesion excision + curettage + scar repair.And 4 cases(4.6%)underwent negative pressure aspiration under ultrasound guidance and later underwent abdominal surgery due to an unsatisfactory drop in blood HCG or repeat ultrasound suggesting residual.11 patients(12.6%)underwent bilateral tubal ligation during abdominal surgery simultaneously.2.Results of the univariate analysis: the case group and the control group were significantly different in age(P=0.020),uterine position(P=0.027),gravidity times(P<0.001),parity times(P<0.001),cesarean section times(P<0.001),abortion times(P<0.001),history of abortion after cesarean section(P<0.001),interval between CSP and the last cesarean section(P<0.001)),interval between CSP and the last pregnancy(P=0.049),outcome of last pregnancy(P=0.002),timing of cesarean section(P<0.001),and whether or not entering the first stage of labor(P=0.013).3.Results of the multivariate analysis: parity times ≥2(OR=14.515,95% CI:5.911～35.643,P<0.001),abortion times ≥2(OR=4.470,95% CI: 2.305～8.670,P<0.001),elective cesarean section(OR=2.256,95% CI: 1.158～4.395,P=0.017),and breech position and cephalopelvic disproportion in indications of cesarean section(OR=3.218,95% CI:1.598～6.482,P=0.001)were independent risk factors of cesarean scar pregnancy,and cesarean section at urban and university hospitals(OR=0.403,95% CI: 0.205～0.789,P=0.008)was an independent protective factor of cesarean scar pregnancy.4.Based on the results of the multivariate analysis,the equation was constructed as follows: Y =-2.039 + 2.675 parity times + 1.497 abortion times-0.910 cesarean section at urban and university hospitals + 0.814 elective cesarean section + 1.169 breech position and cephalopelvic disproportion.The Nomogram of cesarean scar pregnancy was constructed based on the equation.Bootstrap method was used by resampling 1000 times for internal validation.The area under curve(AUC)of Nomogram for predicting the probability of cesarean scar pregnancy was 0.835(95% CI: 0.782～0.887).The ROC curve,Calibration Curve and Decision Curve Analysis all indicated that the model had a good predictive effect.Additional clinical data of 12 CSP patients and 48 non-CSP pregnant women with a history of cesarean section were collected for external validation,and the AUC was 0.720(95% CI:0.529-0.910).5.Follow-up analysis of the reproductive outcomes in patients with CSP: among 19 patients with fertility requirements,14 delivered successfully,all by elective cesarean section at full term,without serious perinatal adverse outcomes,and the full-term live birth rate was 73.7%.1 case of placental implantation occurred and the incidence of placental diseases was 5.3%.2 cases of spontaneous abortion occurred and the spontaneous abortion rate was 10.5%.2 cases of CSP occurred again and the recurrence rate of CSP was 10.5%.ConclusionsThe incidence of CSP is the result of multiple factors.Parity times ≥2,abortion times≥2,elective cesarean section,and breech position and cephalopelvic disproportion in indications of cesarean section are independent risk factors for CSP,and cesarean section at urban and university hospitals is an independent protective factor.With a CSP recurrence rate of 10.5% and a full-term live birth rate of 73.7%,this study provides some evidence for the risk of recurrence and rate of pregnancy success after CSP treatment.The incidence of CSP should be reduced by early identification of high-risk patients,strengthening management,recommending long-term and effective contraceptive measures for women without fertility requirement currently,and improving cesarean section techniques in clinical.Based on the above results,this study constructed a Nomogram for predicting the risk of CSP.The model has a good prediction effect and possesses a certain clinical value.