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Evaluation of fetal anthropometric measures to predict the risk for shoulder dystocia
Author(s) -
Burkhardt T.,
Schmidt M.,
Kurmanavicius J.,
Zimmermann R.,
Schäffer L.
Publication year - 2014
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.12560
Subject(s) - medicine , receiver operating characteristic , shoulder dystocia , obstetrics , anthropometry , odds ratio , fetal head , retrospective cohort study , predictive value of tests , area under the curve , positive predicative value , fetus , pregnancy , predictive value , surgery , genetics , biology
Objective To evaluate the quality of anthropometric measures to improve the prediction of shoulder dystocia by combining different sonographic biometric parameters . Methods This was a retrospective cohort study of 12 794 vaginal deliveries with complete sonographic biometry data obtained within 7 days before delivery. Receiver–operating characteristics ( ROC ) curves of various combinations of the biometric parameters, namely, biparietal diameter ( BPD ), occipitofrontal diameter (OFD), head circumference, abdominal diameter ( AD ), abdominal circumference (AC) and femur length were analyzed. The influences of independent risk factors were calculated and their combination used in a predictive model . Results The incidence of shoulder dystocia was 1.14%. Different combinations of sonographic parameters showed comparable ROC curves without advantage for a particular combination. The difference between AD and BPD ( AD – BPD ) (area under the curve ( AUC ) = 0.704) revealed a significant increase in risk (odds ratio ( OR ) 7.6 (95% CI 4.2–13.9), sensitivity 8.2%, specificity 98.8%) at a suggested cut‐off ≥ 2.6 cm. However, the positive predictive value ( PPV ) was low (7.5%). The AC as a single parameter ( AUC = 0.732) with a cut‐off ≥ 35 cm performed worse ( OR 4.6 (95% CI 3.3–6.5), PPV 2.6%). BPD/OFD (a surrogate for fetal cranial shape) was not significantly different between those with and those without shoulder dystocia. The combination of estimated fetal weight, maternal diabetes, gender and AD – BPD provided a reasonable estimate of the individual risk . Conclusion Sonographic fetal anthropometric measures appear not to be a useful tool to screen for the risk of shoulder dystocia due to a low PPV . However, AD – BPD appears to be a relevant risk factor. While risk stratification including different known risk factors may aid in counseling, shoulder dystocia cannot effectively be predicted. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd .