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ORIGINAL RESEARCH |
From the Departments of Obstetrics and Gynecology and Anesthesiology, Northwestern University, Chicago, Illinois.
Address reprint requests to: Beth A. Plunkett, MD, Department of Obstetrics and Gynecology, 333 East Superior Street, Suite 410, Chicago, IL 60611; E-mail: p-beth{at}northwestern.edu.
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ABSTRACT |
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METHODS: Nulliparas with standardized patient-controlled epidural analgesia (0.0625% bupivacaine with fentanyl 2 µg/mL) were randomly assigned to pushing immediately upon complete cervical dilatation (n = 85) or waiting for a strong urge to push (n = 117). Urge to push and patient satisfaction were quantified on 100-mm visual analogue scales. Duration of pushing and total duration of the second stage were analyzed as survival time data.
RESULTS: Women who delayed pushing and those who pushed immediately were similar with respect to maternal characteristics. Women who delayed pushing had a stronger urge to push (P < .01) and a longer second stage (P < .05) than women who pushed immediately. There was no significant difference in the time spent pushing (median 57 versus 62 minutes, respectively) or the median level of patient satisfaction (80 mm for both groups). There were no significant differences in the overall rates of cesarean delivery (6% versus 12%, respectively), cesarean delivery during the second stage (2% in each group), spontaneous vaginal delivery (70% versus 69%, respectively), or neonatal or maternal morbidity.
CONCLUSION: In nulliparas with continuous low-concentration epidural analgesia, delaying pushing until a strong urge is felt does not reduce the duration of pushing in the second stage of labor.
Optimal management of the second stage of labor in women with epidural analgesia remains a matter of debate among many physicians. In the presence of epidural analgesia and concomitant sensory blockade, a parturient may not appreciate a strong urge to push upon reaching the second stage of labor. Some clinicians believe that parturients should begin pushing immediately upon reaching complete cervical dilatation to decrease the length of the second stage and the potential for infectious morbidity, whereas others argue that waiting for a strong urge to push maximizes the efficiency of pushing efforts and reduces the risk of maternal exhaustion and operative delivery. Although several studies have addressed these issues,1–6 results are contradictory as to the benefit to the mother and neonate of delaying pushing efforts. Some studies indicate that waiting for a strong urge to push reduces the total time spent pushing,1,5,6 decreases difficult operative deliveries,1 and reduces maternal fatigue.5 Other studies indicate that waiting for a strong urge to push does not reduce the duration of pushing,2,4 may increase the rate of operative deliveries,4 and increases the incidence of intrapartum fever.1 We hypothesized that delaying pushing efforts until the parturient appreciates a strong urge to push would significantly decrease the duration of pushing as compared with pushing immediately upon reaching complete cervical dilatation. The aim of this study was to determine if waiting for a strong urge to push reduces total pushing time in nulliparas with continuous low-concentration epidural analgesia.
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MATERIALS AND METHODS |
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Participants were randomized to pushing immediately upon reaching complete dilatation or to delaying pushing efforts until feeling a strong urge to push. Randomized assignments were determined through the use of a computer-generated random numbers table. Assignments were kept in opaque envelopes until after patient consent was obtained. Participants underwent serial cervical examinations every 2 hours until reaching 8-cm dilatation. Hourly examinations were performed subsequently until complete dilatation was achieved. Women in the immediate pushing group were encouraged to begin pushing efforts upon reaching complete dilatation. Women in the delayed pushing group were instructed to wait until they appreciated a strong urge to push, defined as 50 mm or greater on an unmarked 100-mm visual analogue scale. The limits of the scale were verbally defined as no urge to push (0 mm) and an overwhelming urge to push (100 mm). If participants did not feel a strong urge to push after 90 minutes, they were asked to start pushing without an urge. In both groups, the urge to push was recorded on the visual analogue scale at the time pushing began. The length of the second stage was measured from the time of reaching complete dilatation to the time of delivery. The length of the pushing stage was measured from initiation of pushing to delivery.
Immediately after delivery, satisfaction with the management of the second stage was quantified using an unmarked 100-mm visual analogue scale. The limits of the scale were verbally defined as unsatisfied (0 mm) and maximally satisfied (100 mm). Pertinent demographic and obstetric characteristics were recorded. Intrapartum fever was defined as a temperature elevation during labor of 100.4F or greater. Maternal hemorrhage was defined as greater than 500 mL of estimated blood loss after a vaginal delivery. All medical records were subsequently reviewed for accuracy of the data.
Statistical analyses were completed using Student t test, 
2 analysis, and Fisher exact test, where appropriate. For variables that were not normally distributed, the Mann–Whitney U test was applied. Duration of pushing and total duration of the second stage were analyzed as survival time data. Kaplan–Meier survival curves were generated, and differences between the groups were compared using the log rank test. All data were analyzed initially by intention to treat. A post-hoc analysis was subsequently performed comparing the group of women who felt a strong urge to push with those women who did not. All tests were two sided, and statistical significance was defined as P < .05. Data analysis was performed using Minitab 13 (Minitab Inc, State College, PA) and Stata 6 (Stata Corp, College Station, TX).
A power analysis was performed for the primary outcome of interest, ie, duration of pushing during the second stage of labor. If women in the pushing immediately group pushed for 1.4 ±1.0 hours,7 81 patients in each group would be needed to demonstrate a difference of 30 minutes between the two groups with 80% power at an 
= 0.05.
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RESULTS |
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). There were no significant differences between the groups with respect to maternal demographic factors such as age, gestational age, body mass index, race, or insurance status (Table 1). Labor characteristics were similar with respect to dilatation at the time of epidural placement, fetal station at the time of complete dilatation, and position at the time of delivery (Table 2). There were more labor inductions in the pushing immediately group than in the delayed pushing group (P < .05).
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). The number of patients receiving anesthesia-administered bolus doses during the first or second stage of labor (48% in the delayed pushing group and 41% in the immediate pushing group) was not significantly different between the two groups. Twelve individuals in the delayed pushing group (11%) and five in the immediate pushing group (6%) had the basal infusion rate decreased during the labor course, with no significant difference between the groups. All epidural catheters in each group were functional during the second stage.
Labor outcomes were similar between the delayed pushing and the immediate pushing groups (Table 3). There was no difference with respect to the overall rate of cesarean delivery (6% versus 12%, respectively), cesarean deliveries during the second stage of labor (2% in each group), spontaneous vaginal delivery (70% versus 69%, respectively), or operative vaginal delivery (24% versus 19%, respectively). Maternal complication rates were similar with respect to intrapartum fever, hemorrhage, and third- and fourth-degree perineal lacerations. Fetal outcomes were similar as measured by 5-minute Apgar scores, cord blood pH, and neonatal intensive care unit admissions.
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). However, there was no significant difference in the total time spent pushing (median 57 minutes, interquartile range 34–126 minutes in the delayed group versus median 62 minutes, interquartile range 33–112 minutes in the push immediately group; P > .05, log rank test, Figure 3). Maternal satisfaction with the second stage of labor was similar between groups (median 80 mm for both groups).
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DISCUSSION |
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Although our findings are consistent with two studies that showed an increase in the length of the second stage of labor without a decrease in the duration of pushing,2,4 our analgesic management strategy was quite different from either of these studies. In these earlier reports, women who "delayed" pushing were encouraged to delay for 2 hours or until the fetal head was visible at the perineum. Serial bolus epidural doses were given to augment analgesia and suppress a parturient’s urge to push. We do not believe that this approach accurately reflects current-day clinical management of the second stage.
In contrast to our findings, Fraser et al1 in a large (n = 1862) randomized, multicenter, controlled trial found a decreased pushing interval in the delayed pushing group. In their study, women in the "delayed pushing" group were encouraged to delay pushing efforts until they experienced an "irresistible urge" or the fetal head was present on the perineum. Of note, parturients in Fraser et al’s1 study experienced a considerably longer second stage in both the delayed pushing group (median 187 minutes) and the immediate pushing group (median 123 minutes) as compared with our study (median 99 and 69 minutes, respectively). We believe that this marked difference in outcome is a result of the analgesia used. In their study, participants received neuraxial analgesia with fentanyl and 0.125% bupivicaine as compared with the lower anesthetic concentration (0.0625% bupivicaine) used in our study. This lower anesthetic concentration has been shown to significantly decrease the frequency and severity of motor blockade as compared with the higher concentration8 and does not prolong the second stage of labor relative to women without regional analgesia.9 Thus, we believe that using this low-concentration epidural analgesic regimen that is associated with decreased motor blockade eliminates any benefit that may be gained by a strategy of delaying pushing efforts until the patient perceives a strong urge to push.
Several limitations to this study should be considered. Despite computer-generated randomization, the pushing immediately group included 85 patients compared with the 117 patients in the delayed pushing group. Because of the imbalance in the distribution, we reexamined the randomization process for evidence of improper enrollment and found none. We concluded that the uneven distribution between groups did not represent a breach in the randomization process but rather the reality that even chance allows for the occurrence of an unequal distribution.
Similarly, despite randomization, more women in the immediate pushing group underwent induction of labor. This difference could potentially impact both the management and outcomes of the first and the second stage of labor. Induction of labor could increase the risk of cesarean delivery in the first stage of labor.10 However, in our study, the rates of cesarean delivery in both the first and the second stage of labor were similar between the groups, making it unlikely that the uneven distribution of labor inductions played a significant role. Additionally, labor induction could influence the management of the second stage of labor as women who begin their labor course with oxytocin may be more likely to continue oxytocin treatment throughout the second stage of labor. However, at our institution, both the first and second stage of labor are typically managed actively, and oxytocin is used throughout the labor course in the substantial majority of individuals with epidural analgesia.
Also, our study was not blinded. Both the patient and the practitioner were aware of the group assignment before the start of the second stage. This knowledge may have influenced physician management of the second stage of labor, and it may have influenced patient perception with respect to experiencing an urge to push.
Additionally, not all women in the delayed pushing group experienced a strong urge to push before beginning pushing efforts. These women may have begun pushing prematurely because of fetal indications or preferences of the patient or the obstetrician. The intention-to-treat analysis compares the two management approaches of pushing immediately versus delayed pushing and recognizes that strict adherence to either protocol may not be possible in every clinical scenario. The additional analysis of women who did in fact experience a strong urge to push compared with those who did not feel an urge to push showed no significant difference in the duration of pushing and does not alter the findings of the study.
Finally, our study demonstrates that despite randomization to different management strategies in the second stage of labor, the clinical experience was not profoundly different between the two groups. Women in the delayed pushing group waited for only 10 more minutes before beginning pushing efforts than those in the push immediately group, not a clinically important difference. We believe that this reflects the actual clinical circumstances of parturients with low-concentration continuous epidural analgesia and that the conclusions regarding the differing strategies remain valid for women under these clinical conditions. Thus, we conclude that in nulliparous women with low-concentration neuraxial analgesia, delaying pushing efforts until the parturient perceives a strong urge to push provides no benefit with respect to duration of pushing in the second stage of labor.
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Footnotes |
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doi:10.1016/S0029-7844(03)00479-4
Received December 6, 2002. Received in revised form January 27, 2003. Accepted March 5, 2003.
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REFERENCES |
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2. Maresh M, Choong KH, Beard RW. Delayed pushing with lumbar epidural analgesia in labour. Br J Obstet Gynaecol 1983;90:623–7.[Medline]
3. Mayberry LJ, Hammer R, Kelly C, True-Drier B, De A. Use of delayed pushing with epidural anesthesia: Findings from a randomized, controlled trial. J Perinat 1999;19: 26–30.
4. Manyonda IT, Shaw DE, Drife JO. The effect of delayed pushing in the second stage of labor with continuous lumbar epidural analgesia. Acta Obstet Gynecol Scand 1990;69:291–5.[Medline]
5. Hansen SL, Clark SL, Foster JC. Active pushing versus passive fetal descent in the second stage of labor: A randomized controlled trial. Obstet Gynecol 2002;99:29–34.
6. Vause S, Congdon HM, Thornton JG. Immediate and delayed pushing in the second stage of labour for nulliparous women with epidural analgesia: A randomized controlled trial. Br J Obstet Gynaecol 1998;105:186–8.[Medline]
7. Lopez-Zeno JA, Peaceman AM, Adashek JA, Socol ML. A controlled trial of a program for the active management of labor. N Engl J Med 1992;326:450–4.[Abstract]
8. Russell R, Reynolds R. Epidural infusion of low dose bupivacaine and opioid in labour. Anaesthesia 1996;51: 266–73.[Medline]
9. Chestnut DH, Laszewski LJ, Pollack KL, Bates JN, Manago NK, Choi WW. Continuous epidural infusion of 0.0625% bupivacaine-.0002% fentanyl during the second stage of labour. Anesthesiology 1990;72:613–8.[Medline]
10. Seyb ST, Berka RJ, Socol ML, Dooley SL. Risk of cesarean delivery with elective induction of labor at term in nulliparous women. Obstet Gynecol 1999;94:600–7.
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