297: In women with shouder dystocia, what additional factors increase risk of BPI?

additional factors increase risk of BPI? Katherine A Volpe, Yvonne W Cheng, Jonathan Snowden, Keenan E Yanit, Rachel Pilliod, Aaron Caughey Oregon Health & Science University, Department of Obstetrics and Gynecology, Portland, OR, University of California, San Francisco, Department of Obstetrics, Gynecology & Reproductive Sciences, San Francisco, CA, Oregon Health and Science University, Department of Obstetrics and Gynecology, Portland, OR OBJECTIVE: To examine birthweight and other predictors of brachial plexus injury (BPI) in women with shoulder dystocia. STUDY DESIGN: A retrospective cohort study of term pregnancies complicated by shoulder dystocia in California. Birthweight was the primary predictor examined. Univariate and multivariate analysis were performed on the relationship between birthweight and BPI, controlling for maternal race/ethnicity, age, parity, gestational diabetes and operative vaginal delivery. RESULTS: This study included 5,702 deliveries complicated by shoulder dystocia, of which 258(4.5%) resulted in BPI. The incidence of BPI with shoulder dystocia was 0% in neonates 25002999g, 2.8% in neonates 30003499g, 3.5% in neonates 35003999g, 5.4% in neonates 40004499g, 8.1% in neonates 45004999g and 12.8% in neonates 5000g (p 0.001). The association beween birthweight and BPI in women with a shoulder dystocia remained significant regardless of advanced maternal age (p 0.001), nulliparity(p 0.004) and operative delivery(p 0.009). Table 1 depicts a multivariate analyses of race, birtweight, and clinical risk factors for BPI in women with shoulder dystocia (n 5227). When controlling for potential confounders, increasing birthweight was associated with an increasing risk of BPI in women with a shoulder dystocia when compared to 3000-3499g birthweight (4000-4499, AOR 4.22, 95% CI 2.35-7.55, 4500-4999g AOR 6.51, 95% CI 3.41-12.41, 5000g AOR 8.92 95% CI 3.49-22.77). CONCLUSION: Increasing birthweight increases the risk of BPI in women with a shoulder dystocia independent of advanced maternal age, race, parity, induction of labor or operative vaginal delivery. 298 Factors influencing the accuracy of clinical estimation of fetal weight in term pregnancies Katherine Goetzinger, Anthony Odibo, Anthony Shanks, Kimberly Roehl, Alison Cahill Washington University in St. Louis, Department of Obstetrics and Gynecology, St. Louis, MO OBJECTIVE: The inherent subjective element of Leopold maneuvers for estimating fetal weight weakens it as a clinical tool. Clinical factors such as maternal discomfort in labor and progressive descent of the fetal head with advancing gestational age (GA) may further differentially impact the accuracy of clinical estimation of fetal weight (EFW). We aimed to evaluate whether clinical characteristics at the time of admission further reduce the accuracy of clinical EFW in term pregnancies. STUDY DESIGN: A retrospective cohort study of consecutive patients who presented for labor at 37 weeks gestation over a 4 year time period. Clinical EFW was performed using Leopold maneuvers at the time of admission. Patients with an ultrasound EFW were excluded. A Pearson correlation coefficient (r) was used to evaluate the linear relationship between clinical EFW and actual birth weight (BW). GA, fetal station, and admission diagnoses of spontaneous labor v. induction of labor (IOL) were evaluated with respect to their impact on clinical EFW. The primary outcome was defined as an absolute error between clinical EFW and actual BW 500 grams. Secondary outcomes included overall absolute error, absolute percent error [(EFWBW)/BW*100], and absolute percent error 10%. RESULTS: Of 4,121 patients, 3,797 (92.1%) had a clinical EFW performed at the time of admission. The overall correlation between clinical EFW and actual BW was weak. (r 0.4) The proportion fetal weight estimates with an absolute error 500 grams significantly decreased with increasing GA with a nadir at 40 weeks gestation (p10%. There was no difference in absolute error 500 grams when comparing patients admitted with spontaneous labor v. IOL (24.1% v. 26.3%; p 0.15) and comparing patients with fetal station 0 and 0 at the time of admission (24.8% v. 24.3%; p 0.84). CONCLUSION: The predictive value of Leopold estimates of fetal weight has a J-shaped relationship with increasing GA, reaching its best accuracy at 40 weeks. Despite this finding, the overall predictive value remains disappointing. www.AJOG.org Diabetes, Labor, Medical-Surgical-Disease, Obstetric Quality & Safety, Prematurity, Ultrasound-Imaging Poster Session II