///2017 Abstract Details
2017 Abstract Details2019-08-02T15:54:53-06:00

A retrospective cohort assessment of the impact of an anesthetic intervention during the second stage of labor

Abstract Number: T-53
Abstract Type: Original Research

Allana M Munro BScPharm MD FRCPC1 ; Victoria M Allen MD MSc FRCSC2; Ronald B George MD FRCPC3


Adverse maternal and perinatal outcomes increase with prolonged duration of the second stage of labor.(1) An anesthetic intervention known as a “top-up” may be used to optimize labor analgesia, especially in the second stage of labor, to reduce the rate of cesarean deliveries, mid-pelvic procedures, and high degree perineal tears seen with sub-optimal pain control.(2) The first study objective was to define population characteristics of nulliparous patients who received a labor epidural and had a second stage longer than one hour. The second objective was to estimate the incidence of top-ups that occur and the final objective was to describe population characteristics of women who received a top-up compared to women who did not.


A population-based cohort analysis was performed using data derived from a provincial perinatal database from January 2013 to December 2014. With institutional ethics board approval, obstetrical and anesthetic databases identified women who met inclusion criteria. The provincial protocol for linking charts was followed to match patients who received a top-up with predetermined clinical outcomes. Outcomes between groups were evaluated using χ2 or Student’s t-test, as appropriate. Logistic regression was used to address potential confounders between variables. Significance was set at p<0.05.


There were 1462 women eligible for study inclusion. The mean maternal age in this nulliparous group was 29±5, and most women were Caucasian (79%), non-smokers (83%), and had post-secondary education (77%). Augmentation or induction of labor was required for 77%. Cesarean delivery and assisted vaginal delivery rates were 12% and 19%, respectively. Most women received a standard epidural (70%); while 30% had a combined spinal epidural. Seven percent (106/1462) of women required a top-up during the second stage of labor; these women were more likely to be Caucasian (90% vs 78%, p=0.02), non-smoking (90% vs 83%, p=0.08), to have augmentation or induction of labor (88% vs 76%, p<0.01), to have larger weight infants (3635g vs 3459g, p <0.001), to have a longer second stage of labor (301 min vs. 171 min, p<0.00), and to undergo assisted vaginal (41% vs 17%, p<0.001) or cesarean delivery (26% vs 11%, p<0.001), compared to women without a top-up. When controlling for potential covariates, top-ups and augmentation/induction were strongly associated with the risk of cesarean delivery (OR 4.3, 95% CI 2.5-7.5; OR 3.5, 95% CI 1.9-6.6, respectively).


Seven percent of women required a top-up in the second stage of labor. These women had a longer second stage of labor and were more likely to require a cesarean or assisted vaginal delivery. Women requiring top-ups were more likely to have predictors of difficult labor such as medical augmentation and larger weight infants but were still more likely to have spontaneous vaginal delivery overall.

1 Obstet Gynecol 2009:113(6)1248-58

2 AJOG 2008:199(5)500e1-6

SOAP 2017