P05.01: Values of automated uterine volume scanner to predict uterine rupture and dehiscence with scar uterus

Abstract

To evaluate value of measurements of thickness of lower uterine segment in women after a previous Caesarean delivery by automate volume scanner. 200 pregnant women with previous Caesarean delivery were recruited to measure the thinnest thickness of the lower uterine segment and thickness of the plane 6 cm above the thinnest plane. Then ratio of thinnest thickness of the lower uterine segment and the thickness of that plane could be calculated. Receiver operating characteristic (ROC) curve was drawn by the thinnest thickness and the ratio respectively with the intraoperative uterus pathological state. From the ROC, the cut-off value of the thinnest thickness of lower uterine segment and ratio to predict uterine defect was obtained. Meanwhile, two groups of sensitivity, specificity, positive predictive value, negative predictive value could be calculated with the cut-off value. Furthermore, combined the thinnest thickness and ratio to predict the uterine defect was tested. The third group of data like that could be got as well. There are 14 uterine defects in all the recruited pregnant women. The area under ROC of the thinnest thickness is 0.857 (P < 0.001). Cut off points for predicting uterine defect was 2.3 mm. Sensitivity, specificity, positive predictive value, negative predictive value corresponding to cut-off value was 80.0%, 87.0%, 25.5%, 98.7% respectively. In addition, the area under ROC of the ratio is 0.868 (P < 0.001). Cut off points was 36%. Sensitivity, specificity, positive predictive value, negative predictive value was 88.0%, 80.0%, 33.3%, 98.2%. When combined the two cut-off point to predict uterine defects, the Sensitivity, specificity, positive predictive value, negative predictive value was 93.3%, 72.4%, 21.2%, 99.3%. Combined the thinnest thickness of the lower uterine segment and the ratio could obviously increase the accuracy of the prediction of uterine defects by performing the automated volume scanner. The automated volume scanner is good means to evaluate the thickness of lower uterine segment.