CONCLUSION: Several conditions of the antepartum and peripartumperiod are associated with disproportionately higher risks of amnioticfluid embolism. Given the significant mortality of AFE, extreme cau-tion should be exercised in cases demonstrating a combination ofthese morbidities and clinical signs of AFE.

784 Failure rate and delivery-related maternal morbidity invacuum delivery, forceps delivery, or a combination of bothAlex Fong1, Erica Wu1, Deyu Pan2, Dotun Ogunyemi3, JudithChung1

1University of California, Irvine, Obstetrics and Gynecology, Orange, CA,2Charles Drew University of Medicine and Science, Research SLI, Los Angeles,CA, 3University of California, Los Angeles, Obstetrics and Gynecology, LosAngeles, CAOBJECTIVE: To assess the differences in delivery-related morbidity andfailure rate when comparing vacuum delivery, forceps delivery, orcombined use of both.STUDY DESIGN: We used 2001-2007 California discharge data to iden-tify cases of forceps and vacuum delivery via ICD-9. After eliminatingcases with incomplete data, we identified 202,439 cases of vacuum,13,555 cases of forceps, and 710 cases where both were used. We usedlogistic regression to adjust for potential confounders.RESULTS: Morbidities increased in forceps compared to vacuum de-liveries included third/fourth degree lacerations (OR 2.07, 95%CI1.98-2.16), postpartum hemorrhage (OR 1.51, 95%CI 1.39-1.64),manual extraction of placenta (OR 1.35, 95%CI 1.17-1.55), pelvichematoma requiring evacuation (OR 2.05, 95%CI 1.44-2.91), andcervical laceration repair (OR 1.73, 95%CI 1.27-2.36). There was atrend towards increased risk of thromboembolic events in forcepsdeliveries (OR 2.93, 95%CI 1.00-8.62).When a combination of both instruments was used, third/fourth

degree lacerations were increased compared to both vacuum (OR2.77, 95% CI 2.36-3.26) and forceps (OR 1.39, 95% CI 1.80-1.64).Postpartum hemorrhage was increased compared to vacuum as well(OR 1.81, 95% CI 1.33-2.47). Compared to forceps deliveries, vacuumdeliveries were more associated with shoulder dystocia (OR 1.43, 95%CI 1.28-1.60).Forceps had the lowest failure rate (2.14%), followed by increased

failure rates in combined use (3.66%, OR 1.85, 95% CI 1.22-2.79) andvacuum (5.60%, OR 2.65, 95% CI 2.37-2.97).CONCLUSION: Forceps delivery is the most successful in achieving vag-inal delivery but appears to be associated with several delivery-relatedmorbidities. Combining both vacuum and forceps is more successfulthan vacuum alone, but is no better than forceps alone, and is associ-ated with even further morbidity. These results, in conjunction with

each method’s neonatal risks, should be considered prior to contem-plating use of vacuum, forceps, or both at delivery.

785 Antepartum risk factors and delivery-relatedmorbidities in cases of failed operative vaginal deliveriesAlex Fong1, Deyu Pan2, Dotun Ogunyemi3, Judith Chung1

1University of California, Irvine, Obstetrics and Gynecology, Orange, CA,2Charles Drew University of Medicine and Science, Research SLI, Los Angeles,CA, 3University of California, Los Angeles, Obstetrics and Gynecology, LosAngeles, CAOBJECTIVE: To identify antepartum clinical factors associated with anincreased risk of failed operative vaginal delivery, as well as to charac-terize differences in delivery-related morbidities.STUDY DESIGN: Using the 2001-2007 California Health Discharge Da-tabase, we identified 205,060 cases of successful operative vaginal de-livery and 17,601 cases of failed operative vaginal delivery after ex-cluding cases which were extremes of age or were missing race data.Cases were identified by ICD-9-CM coding. Adjustments were madefor potential confounders using logistic regression.RESULTS: Subjects were more likely to have failed operative vaginaldeliveries if they had pre-gestational diabetes (OR 3.51, 95% CI 3.04-4.04), chronic hypertension (OR 2.45, 95% CI 2.12-2.85), or asthma(OR 2.36, 95% CI 2.13-2.62). Obese subjects were found to have morethan a 7-fold higher (OR 7.28, 95% 6.64-7.97) odds of failed operativevaginal delivery, as were deliveries complicated by macrosomic fetuses(OR 3.45, 95% CI 3.26-3.75) and obstructed labor (OR 6.15, 95% CI5.89-6.42). Delivery-related morbidities increased in cases of failedoperative vaginal deliveries included uterine rupture (OR 11.04, 95%CI 7.27-16.78), cervical lacerations (OR 1.45, 95% CI 1.08-1.93), andhysterectomy (OR 2.76, 95% CI 1.36-5.58).CONCLUSION: Several antepartum factors appear to be independentlyassociated with an increased risk of failed operative vaginal delivery.Most notably, subjects who are obese or have an obstructed labor have

Risk factors associated withamniotic fluid embolism

Adjusted for age, race/ethnicity, insurance type, hypertensive disease,obesity (unless variable being adjusted is primary outcome).* � incidence expressed as cases per 100,000; � � Results expressed as aOR (95% confidenceinterval).

Differences in delivery-related morbidity betweenvacuum, forceps, and combined use of both

Missing value denotes insufficient cases available to calculate odds ratio.Results expressed as adjusted OR (95% CI).

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Supplement to JANUARY 2013 American Journal of Obstetrics & Gynecology S329

a 6 to 7-fold higher odds. Failed operative vaginal deliveries are alsoassociated with several highly morbid delivery-related risk factors(e.g. hysterectomy). This information may help identify and assist incounseling subjects at extremely high risk of failed operative vaginaldelivery, especially when weighing the potential maternal and neona-tal risks of failed operative vaginal deliveries.

786 Predictors of prolonged skin incision to delivery intervalin cesarean: the relative impact of obesityAndrea Edlow1, Rachel Villalon2, Betul Sisman2, Michael House1

1Tufts Medical Center, Department of Obstetrics and Gynecology, Division ofMaternal-Fetal Medicine, Boston, MA, 2Tufts Medical Center, Department ofObstetrics and Gynecology, Boston, MAOBJECTIVE: Obesity is an independent risk factor for cesarean delivery(CD). Obstetricians’ concern about the ability to perform a rapid CDmay contribute to the increased risk of CD in obese patients. However,multiple other factors may affect the skin incision to delivery interval(SKTDINT) in cesarean. We sought to assess risk factors for prolongedSKTDINT in a cohort of women at a single academic institution.STUDY DESIGN: A retrospective cohort study was conducted. Patientsundergoing CD between 2010 and 2012 at our tertiary care centerwere identified. Women with multiple gestations, and those lackinginformation about delivery interval or predictors of prolonged SKT-DINT were excluded. Prolonged SKTDINT was defined as � 10 min-utes. Obesity was defined as delivery BMI � 35. Computerized med-ical records were used to obtain demographic and obstetricalhistories. Statistical analyses were performed using Chi square andunivariate logistic regression. Associations of interest were adjustedfor potential confounders using multivariable logistic regression.RESULTS: 582 women were identified who met study criteria. 409 hadSKTDINT � 10 mins. Mean SKTDINT was 3.7 minutes longer inobese women, compared to those with BMI � 35 (15.9 vs 12.2 min,p�0.001). However, in women undergoing emergent CD, BMI was

not significantly associated with SKTDINT � 10 mins (p�0.8). In amultivariable logistic regression model, BMI had the lowest impact onSKTDINT � 10 mins, while experience of primary surgeon, prior CD,and less urgent indication for CD were associated with the greatestodds of longer delivery time (Table 1).CONCLUSION: Obesity is associated with a significantly longer timefrom skin incision to delivery, even after controlling for confounders.However, when emergent delivery was necessary, BMI did not signif-icantly impact SKTDINT. Obstetricians should weigh prior surgeriesand surgeon experience, in addition to BMI, when making clinicaldecisions about how rapidly CD can be performed.

787 Prediction of successful trial of labor after cesareandelivery: a validation study in the upper MidwestAngelica Garrett1, Sherif El Nashar1, Todd Stanhope1,Adrianne Racek1, Myra Wick1, Jennifer Tessmer-Tuck1,Mary Marnach1, Abimbola Famuyide1

1Mayo Clinic, Obstetrics and Gynecology, Rochester, MNOBJECTIVE: Despite its wide use, only one study to date has validatedthe model published by Grobman and colleagues for predicting suc-cessful trial of labor after Cesarean delivery (TOLAC). The objectiveof this study is to validate the Grobman model in a tertiary institutionin the Midwest.STUDY DESIGN: This historical cohort study includes women who at-tempted TOLAC at a single Midwestern tertiary center over an elevenyear period (2000-2010). Data collected included baseline demo-graphics, intrapartum variables including progression of labor, ma-ternal complications, and neonatal outcomes. The primary outcomewas successful TOLAC. Univariate and multivariate logistic regres-sion models were used to identify predictors of successful TOLAC andto compare the resultant model with the Grobman model (JMP 9.0,SAS Inc Carey, NJ).RESULTS: Of 852 women who attempted TOLAC, 637 were successful(77.7%, 95% CI 74.7, 80.4%). Relevant baseline characteristics arepresented in the Table. After univariate analyses, prior vaginal deliv-ery, prior successful TOLAC and no prior Cesarean delivery for ab-normal labor were significantly associated with successful TOLACwith unadjusted odds ratios (OR) of 4.46, 7.03, and 1.82, respectively.Multivariate analysis suggested age �30 years, prior vaginal delivery,and prior successful TOLAC were independent predictors of success-ful TOLAC with adjusted ORs of 1.47, 2.31 and 3.59, respectively(Table). A model including all Grobman variables revealed ROC-AUC 0.73 compared with 0.75 in the original publication. When di-vided by decile, there was a strong correlation between predicted andobserved success rates in our cohort (Figure). Finally, Grobmanmodel accurately predicted TOLAC success rate as 76.1% (95%CI75.0,77.2%) which is very close to observed success rate of 77.7%.CONCLUSION: The Grobman model was a reliable predictor of success-ful TOLAC in our cohort. Age �30 years, prior vaginal delivery, and

Incidence of delivery-related morbidities in failedvs. successful operative vaginal deliveries

Adjusted for age, race/ethnicity, insurance type, hypertensive disease.*� Expressed as cases per 1000.

Risk factors for prolonged skin incision todelivery interval in cesarean section

CD, cesarean delivery; N/A, not applicable; REF, reference.

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S330 American Journal of Obstetrics & Gynecology Supplement to JANUARY 2013