Oxytocin use in grand-multiparous patients: safety and complications.

OBJECTIVE: To determine whether the use of oxytocin for the augmentation of labor in grandmultiparous women increases the risk of peripartum complications. STUDY DESIGN: During the years 1989-97, 11 075 grand-multiparous women delivered at our institution. In 424 grand-multiparous women, intravenous oxytocin was used for augmentation of labor. The control group consisted of the other 10 651 grand-multiparous women. All women were monitored for fetal heart rate and uterine contractions. We compared the rates of maternal and perinatal complications in these two groups by using chi(2) analysis and Fisher's exact test when appropriate. RESULTS: No significant differences were found between the oxytocin and the control groups in the rates of placental abruption, intrapartum fetal death, postpartum hemorrhage, uterine rupture, fetal distress, meconium-stained amniotic fluid, an Apgar score of less than 7 at 5 min, Cesarean section, retained placenta and vaginal and cervical lacerations. In contrast, a significant increase in the rate of vacuum deliveries was observed in patients given oxytocin as compared to controls (3.5% vs. 1.4%, respectively; p = 0.001). CONCLUSIONS: The use of oxytocin in the grand-multiparous parturient was a safe procedure with no significant increase in peripartum complications. However, a higher rate of vacuum deliveries was found.     

Active-phase labor arrest: oxytocin augmentation for at least 4 hours

OBJECTIVE: To assess a labor-management protocol that mandated at least 4 hours of oxytocin augmentation before cesarean delivery for active-phase labor arrest. METHODS: We prospectively evaluated term gravidas in spontaneous labor with active-phase labor arrest (cervix at least 4 cm dilated and 1 cm or less of cervical progress in 2 hours). Exclusion criteria included nonvertex presentation, previous cesarean, multiple gestation, and a nonreassuring fetal heart rate tracing or chorioamnionitis at the time of labor arrest. After the diagnosis of active-phase arrest, oxytocin was initiated with an intent to achieve a sustained uterine contraction pattern of greater than 200 Montevideo units. Cesarean delivery was not performed for labor arrest until at least 4 hours of a sustained uterine contraction pattern of greater than 200 Montevideo units, or a minimum of 6 hours of oxytocin augmentation if this contraction pattern could not be achieved. RESULTS: Five hundred forty-two women were managed by the protocol, and 92% delivered vaginally. The subsequent vaginal delivery rate for parous women who had not progressed (1 cm of cervical dilation or less) despite 2 hours of oxytocin augmentation was 91%, and it was 74% for nulliparas. With no labor progress after 4 hours of oxytocin augmentation, the subsequent vaginal delivery rates were 88% for parous women and 56% for nulliparas. There were no severe maternal complications. One neonate had persistent fetal circulation and one had a positive blood culture, but both did well. CONCLUSION: Extending the minimum period of oxytocin augmentation for active-phase labor arrest from 2 to at least 4 hours was effective and safe.     

Uterine rupture during induced or augmented labor in gravid women with one prior cesarean delivery.

OBJECTIVE: Our purpose was to examine the risk of uterine rupture during induction or augmentation of labor in gravid women with 1 prior cesarean delivery. STUDY DESIGN: The medical records of all gravid women with history of cesarean delivery who attempted a trial of labor during a 12-year period at a single center were reviewed. The current analysis was limited to women at term with 1 prior cesarean delivery and no other deliveries. The rate of uterine rupture in gravid women within that group undergoing induction was compared with that in spontaneously laboring women. The association of oxytocin induction, oxytocin augmentation, and use of prostaglandin E(2) gel with uterine rupture was determined. Logistic regression analysis was used to examine these associations, with control for confounding factors. RESULTS: Of 2774 women in the analysis, 2214 had spontaneous onset of labor and 560 women had labor induced with oxytocin or prostaglandin E(2) gel. The overall rate of rupture among all patients with induction of labor was 2.3%, in comparison with 0.7% among women with spontaneous labor (P =.001). Among 1072 patients receiving oxytocin augmentation, the rate of uterine rupture was 1.0%, in comparison with 0.4% in nonaugmented, spontaneously laboring patients (P =.1). In a logistic regression model with control for birth weight, use of epidural, duration of labor, maternal age, year of delivery, and years since last birth, induction with oxytocin was associated with a 4.6-fold increased risk of uterine rupture compared with no oxytocin use (95% confidence interval, 1.5-14.1). In that model, augmentation with oxytocin was associated with an odds ratio of 2.3 (95% confidence interval, 0.8-7.0), and use of prostaglandin E(2) gel was associated with an odds ratio of 3.2 (95% confidence interval, 0.9-10.9). These differences were not statistically significant. CONCLUSION: Induction of labor with oxytocin is associated with an increased rate of uterine rupture in gravid women with 1 prior uterine scar in comparison with the rate in spontaneously laboring women. Although the rate of uterine rupture was not statistically increased during oxytocin augmentation, use of oxytocin in such cases should proceed with caution.     

Obstetric risk factors and outcome of pregnancies complicated with early postpartum hemorrhage: a population-based study.

OBJECTIVE: The study was aimed to identify obstetric risk factors for early postpartum hemorrhage (PPH) in singleton gestations and to evaluate pregnancy outcome. STUDY DESIGN: A comparison between consecutive singleton deliveries with and without early PPH was performed. Deliveries occurred during the years 1988-2002 in a tertiary medical center. A multivariate logistic regression model was constructed in order to define independent risk factors for PPH. RESULTS: Postpartum hemorrhage complicated 0.4% (n = 666) of all deliveries enrolled in the study (n = 154 311). Significant risk factors for PPH, identified using a multivariable analysis, were: retained placenta (OR 3.5, 95%CI 2.1-5.8), failure to progress during the second stage of labor (OR 3.4, 95%CI 2.4-4.7), placenta accreta (OR 3.3, 95%CI 1.7-6.4), lacerations (OR 2.4, 95%CI 2.0-2.8), instrumental delivery (OR 2.3, 95%CI 1.6-3.4), large for gestational age (LGA) newborn (OR 1.9, 95%CI 1.6-2.4), hypertensive disorders (OR 1.7, 95%CI 1.2-2.1), induction of labor (OR 1.4, 95%CI 1.1-1.7) and augmentation of labor with oxytocin (OR 1.4, 95%CI 1.2-1.7). Women were assigned into three different groups according to the assessed severity of PPH, assuming that the severe cases were handled by revision of the birth canal under anesthesia, and the most severe cases required in addition treatment with blood products. A significant linear association was found between the severity of bleeding and the following factors: vacuum extraction, oxytocin augmentation, hypertensive disorders as well as perinatal mortality, uterine rupture, peripartum hysterectomy and uterine or internal iliac artery ligation (p < 0.001 for all variables). CONCLUSION: Hypertensive disorder, failure to progress during the second stage of labor, oxytocin augmentation, vacuum extraction and LGA were found to be major risk factors for severe PPH. Special attention should be given after birth to hypertensive patients, and to patients who underwent induction of labor or instrumental delivery, as well as to those delivering LGA newborns.     

Rate of uterine rupture during a trial of labor in women with one or two prior cesarean deliveries.

OBJECTIVE: We sought to determine whether there is a difference in the rate of symptomatic uterine rupture after a trial of labor in women who have had 1 versus 2 prior cesarean deliveries. STUDY DESIGN: The medical records of all women with a history of either 1 or 2 prior cesarean deliveries who elected to undergo a trial of labor during a 12-year period (July 1984-June 1996) at the Brigham and Women's Hospital were reviewed. Rates of uterine rupture were compared for these 2 groups. Potential confounding variables were controlled by using logistic regression analyses. RESULTS: Women with 1 prior cesarean delivery (n = 3757) had a rate of uterine rupture of 0.8%, whereas women with 2 prior cesarean deliveries (n = 134) had a rate of uterine rupture of 3.7% (P =.001). In a logistic regression analysis that was controlled for maternal age, use of epidural analgesia, oxytocin induction, oxytocin augmentation, the use of prostaglandin E(2) gel, birth weight, gestational age, type of prior hysterotomy, year of trial of labor, and prior vaginal delivery, the odds ratio for uterine rupture in those patients with 2 prior cesarean deliveries was 4.8 (95% confidence interval, 1.8-13. 2) CONCLUSIONS: Women with a history of 2 prior cesarean deliveries have an almost 5-fold greater risk of uterine rupture than those with only 1 prior cesarean delivery.     

Ripening of the uterine cervix in a post-Cesarean parturient: prostaglandin E2 versus Foley catheter

Objective: To compare the success and complication rates of prostaglandin E₂ tablets (PGE₂) and a Foley catheter for the ripening of the uterine cervix in post-Cesarean section parturients. Study design: The study population in this retrospective cohort study consisted of parturients in their second pregnancy who had undergone Cesarean section in their previous delivery and who underwent ripening of the uterine cervix by using PGE₂ (n = 55) or Foley catheter (n = 161) in the current pregnancy. The control group consisted of 1432 post-Cesarean section parturients without induction of labor. We compared the rates of placental abruption, non-reassuring fetal heart rate patterns, intrapartum fetal deaths (IPFD), uterine rupture, Apgar scores, labor dystocia, severe birth canal lacerations, vacuum deliveries and repeated Cesarean section rates in the three groups by using ANOVA, χ² analysis and Fisher's exact test when appropriate. Results: A significant increase in the rates of labor dystocia during the first stage (30.4% vs. 11.6%, p < 0.01) and repeated Cesarean deliveries (49.1% vs. 35.2%, p < 0.01) were observed in women in whom the Foley catheter was used as compared to controls, respectively. No such changes were demonstrated in the PGE₂ group as compared to the controls. No significant differences were found between the PGE₂ group and Foley catheter group as compared to the controls in rates of placental abruption, IPFD, uterine rupture, fetal distress, birth canal lacerations, vacuum deliveries and Apgar scores. Conclusions: PGE₂ was found to be superior to the Foley catheter for ripening of the uterine cervix in a post-Cesarean parturient, as demonstrated by a lower repeated Cesarean delivery rate.     

Higher rates of tachysystole among patients with clinically apparent uterine leiomyomas

OBJECTIVE: This study was undertaken to determine uterine and fetal heart rate (FHR) tracing patterns associated with clinically apparent uterine leiomyomas. STUDY DESIGN: Uterine and FHR patterns of 44 women with diagnosed uterine leiomyomas were compared with 601 tracings of controls. Tracings were interpreted during the first stage of labor, using the National Institute of Child Health and Human Development Research Planning Workshop guidelines. Stratified analysis that used the Mantel-Haenszel technique was performed to control for confounders. RESULTS: Patients with leiomyomas had higher rates of uterine tachysystole as compared with those without leiomyomas (22.7% vs 1.3%; odds ratio [OR] = 21.8, 95% CI 7.4-65.6; P < .001). No significant differences were noted between the groups regarding FHR patterns. Higher rates'of prostaglandin induction and oxytocin augmentation were noted in the uterine leiomyomas group (6.8% vs 0.8%; P = .005 and 52.3% vs 10.5%; P < .001, respectively). However, controlling for prostaglandin induction and oxytocin augmentation, with the use of the Mantel-Haenszel procedure, did not change the significant association between uterine leiomyomas and tachysystole (weighted OR 12.5, 95% CI 6.2-75.1, and weighted OR 8.7, 95% CI 3.6-43.1, respectively). CONCLUSION: Clinically apparent uterine leiomyomas, although not coupled with abnormal FHR patterns, are associated with higher rates of tachysystole.     

Emergency peripartum hysterectomy: a 9-year review

Objective: To determine the incidence, indications, risk factors, and complications of emergency peripartum hysterectomy. Study design: A retrospective study of the patients requiring an emergency peripartum hysterectomy of a 9-year period was conducted. Emergency peripartum hysterectomy was defined as one performed for hemorrhage unresponsive to other treatment less than 24 h after delivery. Demographic and clinical variables were obtained from the maternal records. Results: There were 34 emergency peripartum hysterectomies out of 117,095 deliveries for a rate of 0.29 per 1,000. Of the 16 cases that were delivered by cesarean section, seven had a previous cesarean section and 18 cases were delivered vaginally, including two using vacuum extraction. Total hysterectomy was performed in 24 patients, and subtotal hysterectomy in ten patients. The indications for hysterectomy were uterine rupture (n=12), placenta accreta (n=10), uterine atony (n=7), and hemorrhage (n=5). There were two maternal deaths, six stillbirths, and two early neonatal deaths. Conclusion: This study identified surgical deliveries, uterine rupture, placenta accreta, and uterine atony as risk factors for emergency peripartum hysterectomy. The most common reason for abnormal placental adherence was a previous cesarean section. Multiparity and oxytocin use for uterine stimulation were among the risk factors for uterine atony that necessitated emergency peripartum hysterectomy.     

A Comparison of Breast Stimulation and Intravenous Oxytocin for the Augmentation of Labor

Background: Breast stimulation to augment labor has been used for centuries in tribal societies and by midwives. In recent years it has been shown to be effective in ripening the cervix, inducing labor, and as an alternative to oxytocin for the contraction stress test. This study compared the effectiveness of breast stimulation with oxytocin infusion in augmenting labor. Methods: Women admitted to the labor ward were eligible for the study if they had inadequate labor with premature rupture of the membranes and met inclusion criteria. They were assigned to oxytocin augmentation or breast stimulation (manual or pump), and were switched to oxytocin in the event of method failure. Outcomes included time to delivery, intervention to delivery, proportion of spontaneous deliveries, and Apgar scores. One hundred participants were needed in each arm of the study to demonstrate a 2- to 3-hour difference in delivery time, with a power of 80 percent. Results: Analysis was performed on 79 women, of whom 49 were in the breast stimulation group and 30 in the oxytocin group. Sixty-five percent of the participants failed breast stimulation and were switched to oxytocin infusion. Although augmentation start to delivery was shorter for the oxytocin group ( p < 0.001), no differences in total labor time occurred between the groups. Nulliparas receiving breast stimulation had more spontaneous (relative risk 1.7, p= 0.04). and fewer instrumental deliveries than those receiving oxytocin (relative risk 0.2, p= 0.02). No significant differences in adverse fetal outcomes occurred between the study groups. Conclusions: The small number of participants and a variety of problems with the conduct of the study prevented the formulation of reliable conclusions from the results. However, the study provided important insights into the feasibility and problems of developing a high-quality randomized trial of augmentation by breast stimulation.     

The continuing effectiveness of active management of first labor, despite a doubling in overall nulliparous cesarean delivery

OBJECTIVE: The purpose of this study was to determine the continuing effectiveness of active management of labor, a protocol that involves early detection and correction of dystocia with oxytocin in spontaneous cephalic nulliparous labor, by analysis of the contribution of this cohort to a doubled overall nulliparous cesarean delivery rate. STUDY DESIGN: This was a retrospective analysis of annually collated institutional data on cesarean delivery and perinatal outcome. RESULTS: From 1989 to 2000, 81,855 women were delivered at the National Maternity Hospital, of whom 34,201 women (42%) were nulliparous; the annual proportion of nulliparous women in spontaneous labor decreased progressively from 83% to 60%; the overall nulliparous cesarean rate increased from 8.1% to 16.6%. Cesarean birth rate among nulliparous women in spontaneous labor, although showing a significant upward trend between 1989 and 2000 (2.4%-4.8%; P = .001), was stable, averaging 5% for the last 8 years (P = .705); the peripartum death rate in this group fell significantly (P = .024). Comparing results for 1989 with results for 2000, nulliparous women in spontaneous labor accounted for 14% of the overall increase in cesarean deliveries (dystocia, 5%), compared with 51% for nulliparous women with induced labor. The perinatal mortality rate in term infants was unchanged. CONCLUSION: Active management of spontaneous first labors remains an effective protocol for the promotion of vaginal delivery with low peripartum mortality rates; factors other than dystocia in spontaneous labor account for the progressive increase in the nulliparous cesarean delivery rate.     

Rate of increase in oxytocin dose on the outcome of labor induction.

OBJECTIVE: To compare the efficacy and safety of arithmetic and geometric increases in oxytocin infusion dosage during induction of labor. METHODS: A total of 120 pregnant women requiring induction of labor at term were randomly assigned to receive oxytocin at dosages increasing arithmetically or geometrically. Maternal demographics, labor delivery data, and newborn outcomes were compared. The setting was the maternity unit of the Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria. RESULTS: The mean maximum rates of oxytocin delivery needed to achieve adequate uterine contractions were similar in the 2 groups (24.66+/-8.34 mU/min vs. 26.38+/-8.77 mU/min, P=0.24). Labor duration was significantly shorter in the geometric progression group (496.33+/-54.77 min vs. 421.34+/-63.91 min, P<0.001). There were no differences in the rates of cesarean sections, vaginal deliveries, or uterine hyperstimulation, or in neonatal outcomes. CONCLUSION: A geometric rise in the rate of oxytocin infusion delivery reduced the duration of labor without affecting the rates of cesarean sections and uterine hyperstimulation, or newborn outcomes.     

Risk factors for symptomatic uterine rupture during a trial of labor: the 1990s

The purpose of this study is to identify pregnancy and labor factors that place women at increased risk for symptomatic uterine rupture during trial of labor following cesarean section. The study population consisted of 16 women with uterine rupture after a trial of labor who were compared with 32 women without uterine rupture after a trial of labor. Using a case-control study design with a 1:2 match, we examined risk factors that might be associated with an increased risk of uterine rupture. Cases were more likely to have an induction of labor with the use of oxytocin and/or amniotomy (56 vs. 34%) and more likely to undergo augmentation with oxytocin (25 vs. 19%) in comparison with controls. In addition, cases were more likely to be given oxytocin (for either induction or augmentation) (75 vs. 50%) and cervical ripening agents (31 vs. 9%) versus controls. Neonates born after uterine rupture had a higher rate of significant acidosis (pH < 7.0, 57 vs. 0%, p = 0.0002) and lower Apgar scores. There was a significantly higher risk of maternal infection (36 vs. 3%, p = 0.003), transfusion (13 vs. 0%, p = 0.03), and longer length of stay in patients with uterine rupture. There is a trend for increased use of augmentation and induction agents to be associated with uterine rupture. Serious maternal and fetal morbidities are increased following uterine rupture.     

Delivery after previous cesarean: a risk evaluation. Swiss Working Group of Obstetric and Gynecologic Institutions

OBJECTIVE: To examine the risks of vaginal delivery after previous cesarean and to find criteria to help decide whether a trial of labor or an elective repeat cesarean should be preferred. METHODS: We evaluated 29,046 deliveries after previous cesarean registered in a pooled database of 457,825 deliveries used to assess quality control in gynecology and obstetrics departments in Switzerland. RESULTS: Among the 17,613 trial-of-labor cases logged (attempt rate 60.64%), the success rate was 73.73% (65.56% after inducing labor and 75.06% after the spontaneous onset of labor). The following complications were significantly more frequent in the previous-cesarean group: maternal febrile episodes (relative risk [RR] 2.77; 95% confidence interval [CI] 2.52, 3.05), thromboembolic events (RR 2.81; CI 2.23, 3.55), bleeding due to placenta previa during pregnancy (RR 2.06; CI 1.70, 2.49), uterine rupture (92 cases; RR 42.18; CI 31.09, 57.24), and perinatal mortality (118 cases, including six associated with uterine rupture; RR 1.33; CI 1.10, 1.62). The postcesarean group also showed a 0.28% rate of peripartum hysterectomy (81 cases; RR 6.07; CI 4.71, 7.83). There was one maternal death in the group, compared with 14 maternal deaths in the group without previous cesarean (no statistical significance). The risk of uterine rupture for patients with previous cesareans was elevated in the trial-of-labor group compared with the group without trial of labor (RR 2.07; CI 1.29, 3.30), but all other maternal risks, including peripartum hysterectomy (RR 0.36; CI 0.23, 0.56), were lower. When comparing the women having a trial of labor, the 70 with uterine rupture more often had induced labor (24.29% compared with 13.92% in the nonrupture group; P = .013), had epidural anesthesia (24.29% compared with 8.44%; P < .001), had an abnormal fetal heart rate tracing (32.86% compared with 8.53%; P < .001), and had failure to progress (21.43% compared with 7.98%; P = .001). CONCLUSION: A history of cesarean delivery significantly elevates the risks for mother and child in future deliveries. Nonetheless, a trial of labor after previous cesarean is safe. Induction of labor, epidural anesthesia, failure to progress, and abnormal fetal heart rate pattern are all associated with failure of a trial of labor and uterine rupture.     

Induction of labor with misoprostol in pregnancies with advanced maternal age

OBJECTIVE: The objective was to compare the efficacy and complications of intravaginal misoprostol application with oxytocin infusion for induction of labor in advanced aged pregnancies with a Bishop score of < 6. STUDY DESIGN: A hundred advanced aged (> or = 35 years) pregnant patients with a Bishop score of < 6 were randomized into two groups. The first group (50 patients) received 50 microg intravaginal misoprostol four times with 4 h intervals and the second group received oxytocin infusion for induction of labor starting from 2 mIU/min and was increased every 30 min with 2 mIU/min increments up to a maximum of 40 mIU/min. The time from induction to delivery, the route of delivery, fetal outcome, and maternal complications were recorded. Statistical analyses were performed using the Mann-Whitney U, Chi-squared and t tests to determine differences between the two groups. A p value < or = 0.05 was considered significant. RESULTS: Misoprostol was superior for induction of labor in advanced aged pregnancies with Bishop score of < 6, as the mean time from induction to delivery was 9.61 +/- 4.12 h and 11.46 +/- 4.86 h in the misoprostol and oxytocin groups respectively, with a significant difference between the groups (p = 0.04). The rate of vaginal delivery was higher in the misoprostol group (84.0%) than in the oxytocin group (80.0%), but the difference did not reach significance (p = 0.60). The rates of placental abruption and postpartum hemorrhage were similar in both groups and no cases of uterine rupture occurred. The 1- and 5-min mean Apgar scores were 6.98 +/- 1.17 to 9.08 +/- 0.99 and 6.88 +/- 1.81 to 9.00 +/- 1.35 in the misoprostol and oxytocin groups respectively, with no significant differences between the groups (p = 0.74, p = 0.83). No cases of asphyxia were present. The rate of admission to the neonatal intensive care unit was similar in both groups. CONCLUSION: Intravaginal misoprostol seems to be an alternative method to oxytocin in the induction of labor in advanced aged pregnant women with low Bishop scores, as it is efficacious, cheap, and easy to use. But large studies are necessary to clarify safety with regard to the rare complications such as uterine rupture.     

Minimum oxytocin dose requirement after cesarean delivery for labor arrest

OBJECTIVE: To estimate the minimum effective intravenous dose of oxytocin required for adequate uterine contraction after cesarean delivery for labor arrest. METHODS: A randomized single-blinded study was undertaken in 30 parturients undergoing cesarean deliveries under epidural anesthesia for labor arrest despite intravenous oxytocin augmentation. Oxytocin was administered as a slow intravenous bolus immediately after delivery of the infant, according to a biased coin up-down sequential allocation scheme. After assisted spontaneous delivery of the placenta, the obstetrician, blinded to the oxytocin dose, assessed uterine contraction as either satisfactory or unsatisfactory. Additional boluses of oxytocin were administered as required, followed by a maintenance infusion. Data were interpreted and analyzed by a logistic regression model at 95% confidence intervals. RESULTS: All patients received oxytocin infusions at a mean +/- standard deviation of 9.8 +/- 6.3 hours before cesarean delivery (maximum infusion dose 10.3 +/- 8.2 mU/min). The minimum effective dose of oxytocin required to produce adequate uterine response in 90% of women (ED90) was estimated to be 2.99 IU (95% confidence interval 2.32-3.67). The estimated blood loss was 1,178 +/- 716 mL. CONCLUSION: Women requiring cesarean delivery for labor arrest after oxytocin augmentation require approximately 3 IU rapid intravenous infusion of oxytocin to achieve effective uterine contraction after delivery. This dose is 9 times more than previously reported after elective cesarean delivery in nonlaboring women at term, suggesting oxytocin receptor desensitization from exogenous oxytocin administration during labor. Therefore, alternative uterotonic agents, rather than additional oxytocin, may achieve superior uterine contraction and control of blood loss during cesarean delivery for labor arrest. LEVEL OF EVIDENCE: I.     

Oxytocin augmentation in grandmultiparous parturients: to give or not to give?

Objective  The present editorial was aimed to determine policies toward the use of oxytocin for labor augmentation among grandmultiparous (above 5 deliveries) parturients (GMPs). Study design  A questionnaire regarding attitudes toward oxytocin augmentation during labor among GMPs was distributed to all chairpersons of Ob/Gyn departments throughout the country; 20/23 chairpersons responded to the national survey. Results  In all, 85% (17/20) of the chairpersons allowed the use of oxytocin for augmentation of labor in GMPs. Those answering positively to this question did not choose to limit the use of oxytocin for any level of parity. Moreover, 58% (11/19) of them did not obligate the concurrent use of intrauterine pressure catheter while using oxytocin augmentation in these patients. Only 22% (4/18) of the medical centers surveyed limited the maximal dose of Oxytocin among GMPs. The limited dose of oxytocin ranged from 8 to 16 μ/min. Alternatives for oxytocin augmentation in GMPs were breast stimulation (30%), and surgical induction (15%). Nevertheless, 50% of the chairpersons found no other suitable alternative for labor augmentation among GMPs. Conclusion  Oxytocin seems like an accepted method for labor augmentation among grandmultiparous women. Moreover, the vast majority of chairpersons did not mandate additional safety measures such as internal uterine catheter or limited dose regimens in these patients.     

Uterine contraction pressures with oxytocin induction/augmentation

Uterine contraction pressures were quantified (in Montetevideo units) in 109 women at term gestation who received oxytocin for induction or augmentation of labor and whose labor resulted in a spontaneous vaginal delivery. Newborn five-minute Apgar scores were greater than or equal to 8 in 108 of the 109 neonates, and no immediate neonatal morbidity was attributable to the oxytocin stimulation of labor. Women undergoing oxytocin induction had significantly greater uterine contraction pressures than those with oxytocin augmentation. During oxytocin induction 91% of women achieved at least 200 to 224 Montevideo Units and 40% at least 300 Montevideo units versus 77 and 7.7%, respectively, during augmentation of labor. With concurrent fetal monitoring these levels of uterine activity should be sought before consideration of a cesarean delivery because of presumed cephalopelvic disproportion or failure to progress.     

Active phase labor arrest: revisiting the 2-hour minimum

OBJECTIVE: To generate contemporary uterine activity and labor progress data for oxytocin-augmented labor, and assess whether 2 hours of active phase labor arrest with at least 200 Montevideo units justifies cesarean delivery. METHODS: Five hundred and one consecutive spontaneously laboring term women with abnormally progressive labor were managed by a standardized protocol: oxytocin and intrauterine pressure catheter with an intent to sustain at least 200 Montevideo units for 4 hours or more before cesarean for labor arrest. Uterine activity was measured, and maternal and neonatal outcomes were evaluated. With a sample of this size, the upper 95% confidence interval limit for an event with an observed rate of 1% is below 3%. RESULTS: During oxytocin augmentation, nulliparas who were delivered vaginally dilated at a median rate of 1.4 cm/hour versus 1.8 cm/hour for parous women. In both groups, the 5th percentile of cervical dilation rate was 0.5 cm/hour. Thirty-eight women experienced labor arrest for over 2 hours despite at least 200 sustained Montevideo units; 23 (61%) achieved a vaginal delivery. Rates of chorioamnionitis and endometritis for the 38 women were 26%. None of their infants sustained a serious complication, including brachial plexus injury, even though three of the 23 vaginal deliveries (13%) were complicated by shoulder dystocia. CONCLUSION: These data demonstrate that oxytocin-augmented labor proceeds at substantially slower rates than spontaneous labor, and support our previous contention that the criteria of labor arrest for 2 hours, despite at least 200 sustained Montevideo units, are insufficiently rigorous for the performance of cesarean.     

Oxytocin dose and the risk of uterine rupture in trial of labor after cesarean

OBJECTIVE: To examine the association between uterine rupture and oxytocin use in trial of labor after cesarean. METHODS: A case-control study was performed. Cases were all women with uterine ruptures who received oxytocin during a trial of labor after a single cesarean delivery within a 12-year period (n = 24). Four controls undergoing trial of labor after a single cesarean delivery were matched to each case by 500 g birth weight category, year of birth, and by induction or augmentation (n = 96). The study had an 80% power to detect a 40% increase in oxytocin duration or a 65% increase in total oxytocin dose. RESULTS: No significant differences were seen in initial oxytocin dose, maximum dose, or time to maximum dose. Although women with uterine ruptures had higher exposure to oxytocin as measured by mean total oxytocin dose (544 mU higher) and oxytocin duration (54 minutes longer), these differences were not statistically significant. Women with uterine rupture who received oxytocin were more likely to have experienced an episode of uterine hyperstimulation (37.5% compared with 20.8%, P =.05). However, the positive predictive value of hyperstimulation for uterine rupture was only 2.8%. CONCLUSION: Although no significant differences in exposure to oxytocin were detected between cases of uterine rupture and controls, the rarity of uterine rupture limited our power to detect small differences in exposure. In women receiving oxytocin, uterine rupture is associated with an increase in uterine hyperstimulation, but the clinical value of hyperstimulation for predicting uterine rupture is limited.     

A comparison of orally administered misoprostol to intravenous oxytocin for labor induction in women with favorable cervical examinations

OBJECTIVE: The purpose of this study was to compare orally administered misoprostol with intravenous oxytocin infusion for labor induction in women with favorable cervical examinations (defined as a Bishop score of 6 or more). STUDY DESIGN: One hundred ninety-eight women with indications for labor induction and favorable cervical examinations were assigned randomly to receive oral misoprostol or oxytocin induction. Misoprostol, 100 mg, was administered every 4 hours up to 6 doses, or intravenous oxytocin was administered by standardized protocol. RESULTS: One hundred ten (55.6%) women received misoprostol; 88 (44.4%) received intravenous oxytocin. There was no statistically significant difference in the average interval from start of induction to vaginal delivery, being longer in the misoprostol group (789.4 +/- 510.2 minutes) than in the oxytocin group (654.0 +/- 338.2 minutes, P=.19, log-transformed data). Two women had tachysystole develop in each treatment group. More women in the misoprostol group experienced hyperstimulation (7/110, 6.4%) than in the oxytocin group (0/88, P=.02, Fisher exact test). Nine (8.1%) misoprostol-treated women and 8 (9.1%) oxytocin-treated women underwent cesarean deliveries (P=.82). There was a presumed uterine rupture in a misoprostol-treated multipara women. There were no statistically significant differences in neonatal outcomes between the groups. CONCLUSION: Oral misoprostol offers no benefit over intravenous oxytocin for labor induction in women with favorable cervical examinations. It is associated with a higher likelihood of uterine hyperstimulation and may increase the risk of uterine rupture.