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Are there differences in mechanical fetal response between routine and shoulder dystocia deliveries?
S38 SMFM Abstracts 87
ARE THERE DIFFERENCES IN MECHANICAL FETAL RESPONSE BETWEEN ROUTINE AND SHOULDER DYSTOCIA DELIVERIES? ROBERT ALLEN1, STEPHANIE CHA1, LINDSAY KRANKER1, TARA JOHNSON1, EDITH GUREWITSCH2, 1Johns Hopkins University, Biomedical Engineering, Baltimore, Maryland, 2Johns Hopkins University, Gynecology and Obstetrics, Baltimore, Maryland OBJECTIVE: Previous simulations of shoulder dystocia (SD) explored the effect of SD itself on the mechanical response of the fetus. Our objective was to perform an experimental study to explore the variations in fetal response due to routine, unilateral SD (USD) and bilateral SD (BSD) deliveries. STUDY DESIGN: Using a biofidelic maternal model, an instrumented fetal model and a data-acquisition system, we performed 30 experiments. For routine deliveries, we engaged the fetal head and allowed it to progress through cardinal movements using typical uterine contraction forces of 20-35 lbs, stopping the delivery when the head restituted to LOA presentation. For USD deliveries, we obstructed the anterior shoulder on the symphysis pubis; for BSD, the posterior shoulder was also impacted on the sacral promontory. Fetal shoulder widths were varied from 11.5, 12.9 and 12.1 cm, respectively for routine, USD and BSD deliveries. For each delivery we continuously measured head rotation (HR), brachial plexus (BP) stretch and neck extension (NE), selecting peak values for analysis. Maximum BP stretch, NE and HR were compared among groups using ANOVA, with P!0.05 considered significant. RESULTS: The table lists mean peak BP stretch, HR and NE among routine, USD and BSD deliveries. There are no differences among the three types of delivery for anterior BP stretch, HR and NE. CONCLUSION: Quantifiable mechanical response occurs in routine and SD deliveries. Posterior BP stretch is significantly longer for routine deliveries than either USD or BSD deliveries.
89
COMPLICATION RATES IN MULTIPARAS UNDERGOING LABOR INDUCTION COMPARED TO MULTIPARAS EXPERIENCING SPONTANEOUS LABOR LEAH BATTISTA (F)1, DAVID LAGREW2, ANNA MCKEOWN1, DEBORAH WING1, 1 University of California, Irvine, OB/Gyn Maternal Fetal Medicine, Orange, California, 2Saddleback Memorial Medical Center, Maternal Fetal Medicine, Laguna Hills, California OBJECTIVE: The increased complication rates including cesarean section rates are clearly demonstrated for nulliparas undergoing labor induction compared to those experiencing spontaneous labor. The goal of this investigation is to compare complication rates in multiparas undergoing labor induction compared to multiparas experiencing spontaneous labor. STUDY DESIGN: A retrospective cohort using a quality assurance database of prospectively collected data. All multiparas with term, singleton pregnancies in vertex presentation without contraindications to labor at four hospitals from 1/2003-12/2004 undergoing labor induction and spontaneous labor were identified. The groups were compared for various complications of labor and delivery in the mothers and infants. Statistical analysis was done using c2 analysis with rate ratios to compare differences. RESULTS: There were a total of 2,416 women undergoing labor induction and 8,016 women experiencing spontaneous labor in this time period. When induced patients were compared to spontaneous labor patients, cesarean section 7.5% vs.5.4%, RR 1.4 (1.19-1.66), estimated blood loss O500cc 9.4% vs. 6.5%, RR 1.62 (1.26-1.69) and O12 hours labor duration 26.3% vs. 9.8%, RR 2.69 (2.45-2.95) were found to be significantly more common. There were no differences in vaginal/perineal lacerations, estimated blood loss greater than 1000cc, admissions to the NICU, APGAR scores, or operative vaginal delivery between the two groups. CONCLUSION: Labor induction in multiparas increased cesarean section rates, blood loss and chances for prolonged labor. These risks should be shared with paients undergoing labor induction.
88
PREDICTING CEPHALOPELVIC DISPROPORTION (CPD) IN LABOR UTILIZING RITA DRIGGERS1, UTERINE TOCODYNAMOMETRY JANYNE ALTHAUS (F)1, SCOTT PETERSEN1, ALICE COOTAUCO1, KARIN BLAKEMORE1, 1Johns Hopkins University, Gynecology and Obstetrics, Baltimore, Maryland OBJECTIVE: To determine if intrapartum contractions of a particular shape (rapid rise with slower return to baseline) are predictive of CPD. STUDY DESIGN: Prospective cohorts of 100 women each who underwent spontaneous vaginal delivery (SVD) vs Cesarean section (C/S) for CPD or arrest of labor were consecutively identified. Inclusion criteria included term, singleton pregnancies, nulliparity and absence of fetal anomalies. One hour of interpretable EFM was obtained in active labor. Fall to rise (F:R) ratio was calculated by measuring the time for a contraction to return to baseline from its peak (‘‘fall’’) and the time for a contraction to rise to its peak (‘‘rise’’); F:Rs were then averaged over the number of contractions. Data were analyzed using Student’s t-test, Chi-square, Fisher’s exact tests and ANOVA where appropriate. RESULTS: The average F:R ratio was 1.55 for SVD vs 1.77 for C/S (p=0.0003). ANOVA revealed this difference persists when controlling for potentially confounding factors. (Table) Increasing F:Rs were associated with higher birthweights (p=0.06). The positive predictive value (PPV) for CPD increased with increasing F:R in the study subjects: F:R = 1.2, PPV = 50%; F:R = 1.4, PPV=54%; F:R = 1.6 PPV=63%; F:R = 1.8 PPV = 70%; F:R = 2.0, PPV=73%. CONCLUSION: Our study demonstrates a uterine contraction configuration that is more common in those labors destined for C/S due to CPD. This suggests the activation of a potential feedback mechanism by the uterus as it adapts to a relative or absolute CPD.
90
FETAL SAFETY OF UTERO-VAGINAL SODIUM NITROPRUSSIDE APPLICATION IN SHEEP IMMACOLATA BLASI1, BRYAN RICHARDSON2, BRAD MATUSHEWSKI2, SHANNON HEMSTREET2, FABIO FACCHINETTI1, 1University of Modena & Reggio Emilia, Mother-infant Dept., Modena, Italy, 2University of Western Ontario, Physiology & Pharmacology, London, Ontario, Canada OBJECTIVE: The aim of this study is to evaluate the safety of Sodium Nitroprusside (SNP) administration in the cervix of near term sheep. STUDY DESIGN: Chronically catheterized pregnant sheep at w 0.9 gestation were divided into three study groups: Cerv group (n=8) received 0.1 mg/kg estimated maternal body weight of SNP gel (2%) in the extra-amniotic space near the internal os of the cervix; Plac group (n=6) received a placebo gel in a similar volume at the same site; Vag group (n=5) received SNP gel in a similar volume in the vaginal posterior fornix. SNP or placebo gel were administered at 9 am on day one of study with fetal blood gas/pH and blood pressure (FBP) monitored immediately before (time 0) and for 24 hours thereafter. RESULTS: No significant changes were induced by SNP or by Plac except a slight transient increase of fetal lactate just after SNP administration in the cervical than in vaginal group. We also recorded a decrease of fetal Base Excess. Nonetheless, they are minimal and unlikely to be of any clinical significance. FBP does increase in the SNP groups indicating a effect of the drug which is not surprising but generally well tolerated to the extent fetal blood gases and pH remain little changed. However, this may not be the case in the IUGR fetus with a compromise in placental function and oxygenation who may not tolerate so readily these cardiovascular effects if umbilical blood flow is also effected. CONCLUSION: These data demonstrate few, if any, effects of intrauterine and vaginal SNP administration on both cellular oxygenation and cardiovascular indexes. Thus, such treatment could be considered a safe procedure for fetus.
Maternal demographics
Age (yrs) Gestational age (wks) Race (%white) Diabetes (%) Magnesium in labor (%) Epidural (%) Pitocin (%) Induction (%) IUPC (%) ROM (%) Chorioamnionitis Birthweight (g) F:R
SVD
C/S
p-value
23.5 39.3 23 3 4 89 77 45 38 79 8 3218 1.55
25.6 40.0 30 2 5 96 88 65 59 87 23 3562 1.77
0.032 !0.001 0.226 1.00 1.00 0.105 0.041 0.003 0.005 0.132 0.003 !0.0001 0.00003
(data reported as mean D/ÿ SEM, * [ p! 0.05 vs baseline) Lactate
FBP
Time
Cerv
Vag
Plac
Cerv
Vag
Plac
0 0.45 2.5 6 11 24
.8G.1 .9G.1* .8G.1 .8G.1 .8G.1 1G.2
1G0.1 1.2G0.2 1.1G0.1 1.1G0.1 1.4G0.2* 1.2G0.2
.7G.2 1G.6 .9G.3 .8G.2 1.1G.7 1G.3
35G5.6 39G2.3* 38G6.9 38G4.5 43G9.3 46G11.2
40G5 45G3* 43G3 45G3* 45G3 48G5
38G6.5 39G5.6 32G9.3 35G7.8 36G8.6 41G11
ARE THERE DIFFERENCES IN MECHANICAL FETAL RESPONSE BETWEEN ROUTINE AND SHOULDER DYSTOCIA DELIVERIES? ROBERT ALLEN1, STEPHANIE CHA1, LINDSAY KRANKER1, TARA JOHNSON1, EDITH GUREWITSCH2, 1Johns Hopkins University, Biomedical Engineering, Baltimore, Maryland, 2Johns Hopkins University, Gynecology and Obstetrics, Baltimore, Maryland OBJECTIVE: Previous simulations of shoulder dystocia (SD) explored the effect of SD itself on the mechanical response of the fetus. Our objective was to perform an experimental study to explore the variations in fetal response due to routine, unilateral SD (USD) and bilateral SD (BSD) deliveries. STUDY DESIGN: Using a biofidelic maternal model, an instrumented fetal model and a data-acquisition system, we performed 30 experiments. For routine deliveries, we engaged the fetal head and allowed it to progress through cardinal movements using typical uterine contraction forces of 20-35 lbs, stopping the delivery when the head restituted to LOA presentation. For USD deliveries, we obstructed the anterior shoulder on the symphysis pubis; for BSD, the posterior shoulder was also impacted on the sacral promontory. Fetal shoulder widths were varied from 11.5, 12.9 and 12.1 cm, respectively for routine, USD and BSD deliveries. For each delivery we continuously measured head rotation (HR), brachial plexus (BP) stretch and neck extension (NE), selecting peak values for analysis. Maximum BP stretch, NE and HR were compared among groups using ANOVA, with P!0.05 considered significant. RESULTS: The table lists mean peak BP stretch, HR and NE among routine, USD and BSD deliveries. There are no differences among the three types of delivery for anterior BP stretch, HR and NE. CONCLUSION: Quantifiable mechanical response occurs in routine and SD deliveries. Posterior BP stretch is significantly longer for routine deliveries than either USD or BSD deliveries.
89
COMPLICATION RATES IN MULTIPARAS UNDERGOING LABOR INDUCTION COMPARED TO MULTIPARAS EXPERIENCING SPONTANEOUS LABOR LEAH BATTISTA (F)1, DAVID LAGREW2, ANNA MCKEOWN1, DEBORAH WING1, 1 University of California, Irvine, OB/Gyn Maternal Fetal Medicine, Orange, California, 2Saddleback Memorial Medical Center, Maternal Fetal Medicine, Laguna Hills, California OBJECTIVE: The increased complication rates including cesarean section rates are clearly demonstrated for nulliparas undergoing labor induction compared to those experiencing spontaneous labor. The goal of this investigation is to compare complication rates in multiparas undergoing labor induction compared to multiparas experiencing spontaneous labor. STUDY DESIGN: A retrospective cohort using a quality assurance database of prospectively collected data. All multiparas with term, singleton pregnancies in vertex presentation without contraindications to labor at four hospitals from 1/2003-12/2004 undergoing labor induction and spontaneous labor were identified. The groups were compared for various complications of labor and delivery in the mothers and infants. Statistical analysis was done using c2 analysis with rate ratios to compare differences. RESULTS: There were a total of 2,416 women undergoing labor induction and 8,016 women experiencing spontaneous labor in this time period. When induced patients were compared to spontaneous labor patients, cesarean section 7.5% vs.5.4%, RR 1.4 (1.19-1.66), estimated blood loss O500cc 9.4% vs. 6.5%, RR 1.62 (1.26-1.69) and O12 hours labor duration 26.3% vs. 9.8%, RR 2.69 (2.45-2.95) were found to be significantly more common. There were no differences in vaginal/perineal lacerations, estimated blood loss greater than 1000cc, admissions to the NICU, APGAR scores, or operative vaginal delivery between the two groups. CONCLUSION: Labor induction in multiparas increased cesarean section rates, blood loss and chances for prolonged labor. These risks should be shared with paients undergoing labor induction.
88
PREDICTING CEPHALOPELVIC DISPROPORTION (CPD) IN LABOR UTILIZING RITA DRIGGERS1, UTERINE TOCODYNAMOMETRY JANYNE ALTHAUS (F)1, SCOTT PETERSEN1, ALICE COOTAUCO1, KARIN BLAKEMORE1, 1Johns Hopkins University, Gynecology and Obstetrics, Baltimore, Maryland OBJECTIVE: To determine if intrapartum contractions of a particular shape (rapid rise with slower return to baseline) are predictive of CPD. STUDY DESIGN: Prospective cohorts of 100 women each who underwent spontaneous vaginal delivery (SVD) vs Cesarean section (C/S) for CPD or arrest of labor were consecutively identified. Inclusion criteria included term, singleton pregnancies, nulliparity and absence of fetal anomalies. One hour of interpretable EFM was obtained in active labor. Fall to rise (F:R) ratio was calculated by measuring the time for a contraction to return to baseline from its peak (‘‘fall’’) and the time for a contraction to rise to its peak (‘‘rise’’); F:Rs were then averaged over the number of contractions. Data were analyzed using Student’s t-test, Chi-square, Fisher’s exact tests and ANOVA where appropriate. RESULTS: The average F:R ratio was 1.55 for SVD vs 1.77 for C/S (p=0.0003). ANOVA revealed this difference persists when controlling for potentially confounding factors. (Table) Increasing F:Rs were associated with higher birthweights (p=0.06). The positive predictive value (PPV) for CPD increased with increasing F:R in the study subjects: F:R = 1.2, PPV = 50%; F:R = 1.4, PPV=54%; F:R = 1.6 PPV=63%; F:R = 1.8 PPV = 70%; F:R = 2.0, PPV=73%. CONCLUSION: Our study demonstrates a uterine contraction configuration that is more common in those labors destined for C/S due to CPD. This suggests the activation of a potential feedback mechanism by the uterus as it adapts to a relative or absolute CPD.
90
FETAL SAFETY OF UTERO-VAGINAL SODIUM NITROPRUSSIDE APPLICATION IN SHEEP IMMACOLATA BLASI1, BRYAN RICHARDSON2, BRAD MATUSHEWSKI2, SHANNON HEMSTREET2, FABIO FACCHINETTI1, 1University of Modena & Reggio Emilia, Mother-infant Dept., Modena, Italy, 2University of Western Ontario, Physiology & Pharmacology, London, Ontario, Canada OBJECTIVE: The aim of this study is to evaluate the safety of Sodium Nitroprusside (SNP) administration in the cervix of near term sheep. STUDY DESIGN: Chronically catheterized pregnant sheep at w 0.9 gestation were divided into three study groups: Cerv group (n=8) received 0.1 mg/kg estimated maternal body weight of SNP gel (2%) in the extra-amniotic space near the internal os of the cervix; Plac group (n=6) received a placebo gel in a similar volume at the same site; Vag group (n=5) received SNP gel in a similar volume in the vaginal posterior fornix. SNP or placebo gel were administered at 9 am on day one of study with fetal blood gas/pH and blood pressure (FBP) monitored immediately before (time 0) and for 24 hours thereafter. RESULTS: No significant changes were induced by SNP or by Plac except a slight transient increase of fetal lactate just after SNP administration in the cervical than in vaginal group. We also recorded a decrease of fetal Base Excess. Nonetheless, they are minimal and unlikely to be of any clinical significance. FBP does increase in the SNP groups indicating a effect of the drug which is not surprising but generally well tolerated to the extent fetal blood gases and pH remain little changed. However, this may not be the case in the IUGR fetus with a compromise in placental function and oxygenation who may not tolerate so readily these cardiovascular effects if umbilical blood flow is also effected. CONCLUSION: These data demonstrate few, if any, effects of intrauterine and vaginal SNP administration on both cellular oxygenation and cardiovascular indexes. Thus, such treatment could be considered a safe procedure for fetus.
Maternal demographics
Age (yrs) Gestational age (wks) Race (%white) Diabetes (%) Magnesium in labor (%) Epidural (%) Pitocin (%) Induction (%) IUPC (%) ROM (%) Chorioamnionitis Birthweight (g) F:R
SVD
C/S
p-value
23.5 39.3 23 3 4 89 77 45 38 79 8 3218 1.55
25.6 40.0 30 2 5 96 88 65 59 87 23 3562 1.77
0.032 !0.001 0.226 1.00 1.00 0.105 0.041 0.003 0.005 0.132 0.003 !0.0001 0.00003
(data reported as mean D/ÿ SEM, * [ p! 0.05 vs baseline) Lactate
FBP
Time
Cerv
Vag
Plac
Cerv
Vag
Plac
0 0.45 2.5 6 11 24
.8G.1 .9G.1* .8G.1 .8G.1 .8G.1 1G.2
1G0.1 1.2G0.2 1.1G0.1 1.1G0.1 1.4G0.2* 1.2G0.2
.7G.2 1G.6 .9G.3 .8G.2 1.1G.7 1G.3
35G5.6 39G2.3* 38G6.9 38G4.5 43G9.3 46G11.2
40G5 45G3* 43G3 45G3* 45G3 48G5
38G6.5 39G5.6 32G9.3 35G7.8 36G8.6 41G11