PREDICTORS OF SUCCESSFUL EXTERNAL CEPHALIC VERSION AT TERM - A PROSPECTIVE-STUDY

Objective To investigate clinical and ultrasonographic predictors of o utcome of external cephalic version at term. Design Prospective observ ational study. Setting University obstetric unit. Population All exter nal cephalic versions performed over two years (n = 243). Methods Nine teen different clinical and ultrasonographic variables were recorded b efore each procedure. The ability of each of the 19 variables to predi ct the success or failure of external cephalic version was assessed by univariate analysis. The study population was then divided into two s ubgroups of 129 and 114 patients by random allocation using computer g enerated numbers. Logistic regression was performed in each subgroup t o assess the relative importance and independence of the important var iables. The derived regression models were then applied to the other s ubgroup of patients to assess accuracy and reproducibility. Results Th e overall success rate of the procedure was 69.5%. Both regression mod els identified the same three variables as independent predictors of f ailed versions: 1. presenting part engaged; 2. difficult to palpate th e fetal head, and 3. a tense uterus on palpation. The two models corre ctly predicted 75.2% and 84.2% of outcomes in the other subgroup. If u terine tone, which was assessed after administration of tocolytic, was excluded from the analysis, the other two factors remained in the mod els, with the addition of nulliparity as a significant predictor of fa iled external cephalic version. The chance of success of external ceph alic version in the original 243 women was found to be <20% if two of these variables were present, 0% if all three were present, and 94% if none were present. Conclusions The outcome of external cephalic versi on can be predicted by easily available clinical parameters.