Predictors of shoulder dystocia at the time of operative vaginal delivery.
BACKGROUND
It remains uncertain whether clinical factors known prior to delivery can predict which women are more likely to experience shoulder dystocia in the setting of operative vaginal delivery.


OBJECTIVE
We sought to identify whether shoulder dystocia can be accurately predicted among women undergoing an operative vaginal delivery.


METHODS
This was a case-control study of women undergoing a low or outlet operative vaginal delivery from 2005 through 2014 in a single tertiary care center. Cases were defined as women who experienced a shoulder dystocia at the time of operative vaginal delivery. Controls consisted of women without a shoulder dystocia at the time of operative vaginal delivery. Variables previously identified to be associated with shoulder dystocia that could be known prior to delivery were abstracted from the medical records. Bivariable analyses and multivariable logistic regression were used to identify factors independently associated with shoulder dystocia. A receiver operating characteristic curve was created to evaluate the predictive value of the model for shoulder dystocia.


RESULTS
Of the 4080 women who met inclusion criteria, shoulder dystocia occurred in 162 (4.0%) women. In bivariable analysis, maternal age, parity, body mass index, diabetes, chorioamnionitis, arrest disorder as an indication for an operative vaginal delivery, vacuum use, and estimated fetal weight >4 kg were significantly associated with shoulder dystocia. In multivariable analysis, parity, diabetes, chorioamnionitis, arrest disorder as an indication for operative vaginal delivery, vacuum use, and estimated fetal weight >4 kg remained independently associated with shoulder dystocia. The area under the curve for the generated receiver operating characteristic curve was 0.73 (95% confidence interval, 0.69-0.77), demonstrating only a modest ability to predict shoulder dystocia before performing an operative vaginal delivery.


CONCLUSIONS
While risk factors for shoulder dystocia at the time of operative vaginal delivery can be identified, reliable prediction of shoulder dystocia in this setting cannot be attained.
Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL. Electronic address: anatlivs@gmail.com.
Anna
A
Palatnik
Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
William A
WA
Grobman
Kaiser Permanente Northern California, San Francisco, CA.
Madeline G
MG
Hellendag
Feinberg School of Medicine, Northwestern University, Chicago, IL.
Timothy M
TM
Janetos
Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
Dana R
DR
Gossett
Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
Emily S
ES
Miller
D000328:Adult; D016022:Case-Control Studies; D003661:Decision Support Techniques; D036861:Delivery, Obstetric; D004420:Dystocia / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D011247:Pregnancy; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity
forceps; operative vaginal delivery; shoulder dystocia; vacuum