A Study On The Analysis Of Clinical Characteristics And Establishment Of Prediction Model Regarding To Uterine Rupture Of Unscarred Uterus During Perinatal Period

Objective To retrospectively analyze the clinical characteristics of uterine rupture between scarred uterus and unscarred uterus,to screen the high-risk factors in association with uterine rupture of unscarred uterus,and to establish a prediction model to predict uterine rupture of unscarred uterus during perinatal period.Methods This is a multi-center study.All participants were collected from the following medical units:Women’s hospital Zhejiang University School of Medicine(from January 1999 to December 2021),**Maternal and Child Health Hospital(January 2015 to December 2021),The Fourth affiliated Hospital Zhejiang University School of Medicine(from January 2018 to December 2021),Hangzhou Maternity and Children Hospital(from January 2004 to December 2021)and Yiwu Central Hospital(January 2005 to December 2021).Consequently,fifty-two patients were recruited in the current study.All of the Fifty-two patients were then divided into two groups according to previous history of uterine surgery:the experiment group included 28 patients without previous history of uterine surgery and the control group included 24 patients with previous history of uterine surgery.The differences between the two groups were statistically compared,and the following factors were included for further analysis:1)general clinical characteristics:participants’ age,gestational age,gestational weeks,previous history of dilation and curettage(D&C);2)clinical manifestation:abdominal pain,abdominal distension,nausea,vomiting,vaginal bleeding;3)high risk factors:previous history of induced labor,previous history of cesarean section,previous history of other operations on uterus,uterine malformation,macrosomia,multiple pregnancy,prolonged labor,and obstructed labor;4)therapeutic strategies:hysterectomy or conservative operation,intraoperative bleeding,hemodynamic instability,placenta percreta,location and size of uterine rupture;5)prognosis of mothers and infants,neonatal Apgar scores;5)imaging examinations:the consistency and thickness of the lower uterine segment according to ultrasonography before delivery.In order to further analyze the data,subgroup analysis was carried out in this study,and the protocols were as follows:1)the scarred uterus group were divided into three subgroups,such as full-term pregnancy group versus non-full-term group,<28 weeks group versus ≥28 weeks group,maternal age≥35 group versus maternal age<35 group;2)the unscarred uterus group were also divided into three subgroups,namely,gravidity≤1 group versus gravidity ≥2 group,primipara group versus multipara group,D&C<1 group versus D&C≥1 time group.In order to establish a prediction model of unscarred uterine rupture during perinatal period,we selected normal vaginal delivery population as normal controls according to the principle of 1:2 using the random number table method,and Logistic binary regression analysis was conducted to build the mathematical formula.Results The clinical manifestations of uterine rupture regarding to unscarred uterus were less typical than that of scarred uterus,therefore,it was more difficult for the clinicians to make a timely diagnosis and easier to delay the diagnosis or misdiagnosis.Consequently,the complications were much more severe than that of uterine rupture in scarred uterus.The specific statistical results of this study were as follows:Perinatal mortality of fetuses and infants,maternal shock rate and hysterectomy rate were as high as 50%,32.1%and 25%in the unscarred uterine rupture group,while the corresponding data were significantly reduced in the scarred uterine rupture group,namely 33.33%,16.67%and 29.17%.In the unscarred uterine rupture group,the history of gravidity≥2 was the high-risk factor.In Comparison with gravidity≤1 group,the history of D&C and balloon catheter induction of labor were the high risk factors.In aspect of previous history of D&C,61.1%(11/18)of participants received treatment for labor induction in ≥1 D&C group)while 40%(4/10)had no treatment of labor induction in<1 D&C group.Consequently,a significant statistical difference was noted between the two groups(P=0.021),indicating that a previous history of D&C and labor induction for the present pregnancy was the high-risk factor of unscarred uterine rupture.Moreover,the amount of bleeding,risk of massive blood loss and risk of hysterectomy were significantly higher in patients with unscarred uterine rupture who had a history of D&C and received labor induction for the current pregnancy than those without a history of D&C.The relevant data were as follows:1)amount of bleeding,1000± 1436ml versus 2138± 1281ml(D&C<1 group versus D&C≥1 group,P=0.040);2)risk of massive blood loss,30%(3/10)versus 83.3%(15/18)(D&C<1 group versus D&C ≥1 group,P=0.005);3)risk of hysterectomy,0 versus 38.9%(D&C<1 group versus D&C≥1 group,P=0.030).The above-mentioned data also demonstrated that the previous history of abortion was a high-risk factor for unscarred uterine rupture.The prediction model of uterine rupture in unscarred uterus constructed using Logistic binary regression analysis in this study was as follows:Logit(P)=-9.112+(-0.199)× maternal age+0.374 × gestational age+1.720 × parity+(-1.162)× number of previous D&C.Conclusions The high-risk factors of unscarred uterine rupture were as follows:1)a previous history of D&C;2)balloon catheter induction of labor for the present pregnancy;3)a previous history of D&C and administration of labor induction for the current pregnancy.The risk of unscarred uterine rupture was predictable.We encourage the clinicians employ the prediction model developed by the current study to screen the high-risk population and take precautious measurements to prevent uterine rupture in unscarred uterus.