A comparison between the oils Wax (n82) Enriched oil (n82) P value Nulliparas .......................................................................................................................................................................................... 1 15.8% 14.6% .......................................................................................................................................................................................... Perineal tear (grade,%) 2 8.5% 9.7% 0.94 .......................................................................................................................................................................................... 3 1.2% 1.2% .......................................................................................................................................................................................... Suturing time (minSD) 10.76.2 12.26.3 0.38 .......................................................................................................................................................................................... Multiparas .......................................................................................................................................................................................... 1 9.7% 8.5% .......................................................................................................................................................................................... Perineal tear (grade,%) 2 8.5% 3.6% 0.40 .......................................................................................................................................................................................... 3 - - .......................................................................................................................................................................................... Suturing time (minSD) 10.95.2 11.43.9 0.88 .......................................................................................................................................................................................... 0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.335 321 Cervical ripening with hyaluronidase: effect on myometrial contractility in vivo and in vitro Nima Goharkhay 1 , Benjamin Byers 1 , Ancizar Betancourt 1 , Phyllis Orise 1 , George Saade 1 , Egle Bytautiene 1 1 University of Texas Medical Branch, Galveston, Texas OBJECTIVE: We have shown that intracervical injection of hyaluroni- dase can induce cervical ripening and accelerate parturition after in- duction of labor in rats. Hyaluronidase also affects the biophysical properties of the rat cervix consistent with augmented ripening. A common issue using cervical ripening agents is their concomitant effect on uterine activity. The objective of this study was to determine whether hyaluronidase causes an increase in uterine contractility. STUDY DESIGN: Timed pregnant Sprague-Dawley rats were injected intracervically with 100 I.U. of hyaluronidase or saline on day 18 of pregnancy (n=7 or 8 per group). All rats were euthanized at term. Uterine rings were isolated for isometric tension experiments. Cumu- lative dose response curves to oxytocin and hyaluronidase, as well as the maximum contractile response to KCl (60 mM) were obtained and compared between the two groups. RESULTS: There was no difference in the contractile response of rat myometrium to oxytocin between hyaluronidase treated animals and controls (figure). Similarly, exposure of the myometrium to increas- ing doses of hyaluronidase did not cause uterine contractions in either of the study groups (figure). There was no signifiacnt variation in the maximal myometrial response to KCl between groups. CONCLUSION: Despite its effect on cervical maturation, the use of hy- aluronidase is not associated with an increase in uterine contractions or myometrial sensitivity to oxytocin. This makes hyaluronidase a potentially superior agent for pre-induction cervical ripening as com- pared to currently available agents. It may be a safer alternative in women with a history of a previous cesarean delivery, or a candidate for use in outpatient settings. 0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.336 322 Safety of prolonged retention of a sustained-release dinoprostone vaginal insert for labor induction Matthew Brennan 1 , Leo Pevzner 2 , Barbara Powers 3 , Deborah Wing 2 , William Rayburn 1 1 University of New Mexico School of Medicine, Obstetrics and Gynecology, Albuquerque, New Mexico, 2 University of California, Irvine, Obstetrics and Gynecology, Orange, California, 3 Cytokine PharmaSciences, Inc., King of Prussia, Pennsylvania OBJECTIVE: To determine whether there are additional risks when a sustained-release dinoprostone vaginal insert is left in place beyond 12 hours during an induction of labor. STUDY DESIGN: This investigation is a secondary analysis of data col- lected during a large, multi-institutional randomized trial comparing the efficacy and safety of three different sustained-release prostaglan- din vaginal inserts for labor induction. We report here on the subset of subjects who received a vaginal insert releasing dinoprostone at a 0.3 mg/hr rate (Cervidil) and delivered during that hospitalization. Out- comes were compared between those cases in which the insert was removed within 12 hours or kept in place for 12-24 hours. RESULTS: A total of 423 subjects were treated with dinoprostone, and the insert was removed during the first 12 hours in 204 (48.2%) cases and between 12 and 24 hours in 219 (51.8%) cases. Subjects who had the insert in place beyond 12 hours had an increased need for oxytocin and a more prolonged time to delivery but were less likely to have the insert removed due to fetal or maternal complications. Six cases (1.4%) had a failed induction with no labor by 24 hours. The need for cesarean delivery, especially for nonreassuring fetal heart rate pat- terns, did not increase when the insert remained in place beyond 12 hours. Treatment for suspected chorioamnionitis in 15 (6.8%) cases was associated with delayed removal of the insert and prolonged la- bor. Newborn outcomes were favorable, with the small percentage of infants requiring intensive care being similar for the early and delayed removal groups (6.4% vs. 8.7%). CONCLUSION: When the sustained-release dinoprostone vaginal insert was in place for 12-24 hours, there were fewer complications requiring insert removal and no increased risk of cesarean delivery or adverse neonatal events. 0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.337 323 Medio-lateral episiotomy may be protective against anal sphincter injury among primiparas Noah Zafran 1 , Raed Salim 1 , Gali Garmi 1 , Zohar Nachum 1 , Eliezer Shalev 1 1 HaEmek Medical Center, OB&GYN, Afula, Israel OBJECTIVE: To investigate whether a selective medio-lateral episiot- omy affect the incidence of anal sphincter injury (ASI). STUDY DESIGN: Data between the years 1999-2001 (era A) were routine medio-lateral episiotomy was applied were compared with the years 2004-2008 (era B) were restricted medio-lateral episiotomy was im- plemented. Cesarean deliveries, preterm deliveries and multiple ges- tations were excluded from the analysis. Data regarding maternal ob- stetric and demographic characteristics, mode of delivery, rate of episiotomy, perineal tears and neonatal weight and gender were col- lected. Stepwise logistic regression was used in order to estimate the attributed risk for ASI. RESULTS: A total of 24,960 deliveries were included in the analysis. Obstetric and demographic data of all women are presented in table 1. The rate of episiotomy was 30.7% and 10.1% in era A and B respec- tively (P0.01). The rate of ASI was 0.1% and 0.4% in era A and B respectively (P0.01). Using logistic regression for calculating the attributed risks for ASI between the two eras revealed that low parity was the only factor that increased the risk of ASI (OR 2.86 CI 1.96- 4.17). Analyzing the attributed risk among primiparas in era B only revealed that medio-lateral episiotomy was associated with a reduced risk of ASI (OR 0.45 CI 0.20-0.99). Poster Session II Diabetes, Doppler, Labor, Ultrasound-Imaging www.AJOG.org S128 American Journal of Obstetrics & Gynecology Supplement to DECEMBER 2009