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Evidence-based management of the second stage of labor
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Evidence-Based Management of the Second Stage of Labor Brock E. Polnaszek MD , Alison G. Cahill MD, MSCI PII: DOI: Reference:
S0146-0005(19)30150-8 https://doi.org/10.1016/j.semperi.2019.151213 YSPER 151213
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Seminars in Perinatology
Please cite this article as: Brock E. Polnaszek MD , Alison G. Cahill MD, MSCI , EvidenceBased Management of the Second Stage of Labor, Seminars in Perinatology (2019), doi: https://doi.org/10.1016/j.semperi.2019.151213
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TITLE PAGE Title: Evidence-Based Management of the Second Stage of Labor Authors: Brock E. Polnaszek, MD & Alison G. Cahill, MD, MSCI Washington University in Saint Louis School of Medicine, Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine. Saint Louis, MO, United States of America Corresponding Author: Brock E. Polnaszek, Department of Obstetrics and Gynecology, Washington University in Saint Louis School of Medicine, 901 Forest Park Avenue. St. Louis, MO 63108. Phone: 314-565-3765; Fax: 314-747-1490, Email: [email protected]
ABSTRACT The second stage of labor is defined as the time from complete dilation of the cervix to delivery of the fetus. The objective of this seminar is to provide a contemporary, evidence-based approach to management of the second stage of labor. This seminar reviews background maternal and fetal characteristics that impact the duration of the second stage of labor, the recommended evidence-based management (e.g. immediate pushing, manual rotation, operative vaginal delivery), and the maternal/neonatal morbidity clinicians must consider when deciding between operative delivery and a prolonged second stage of labor.
TEXT Fetopelvic proportion and Second Stage Characteristics of the maternal pelvis, fetus, and usually both may impact the progression of the second stage of labor1. Android, anthropoid, gynecoid, and platypelloid pelvic types all influence the way the fetus must progress in labor. Pelvic contractions at the inlet, midpelvis, outlet and/or a combination have been explored based on anatomical measurements. Mengert and Kaltreider showed that the incidence of difficult deliveries was increased when either the shortest anteroposterior diameter was <10 cm or the greatest transverse diameter was <12 cm2. However, no imaging or manual measurements are predictive of a failed vaginal delivery. Pelvimetry is a clinical assessment by obstetric providers that should be used throughout the second stage of labor starting with an assessment of the maternal pelvis and the birth canal the fetus must navigate. Specific fetal characteristics such as size, position, and presentation may impact the progression of the second stage of labor as well1. With an estimated fetal weight of 4,500 grams or more, a prolonged or arrest of descent during the second stage is an indication for cesarean delivery3,4. Research has consistently demonstrated an increased risk of shoulder dystocia when a macrosomic fetus is delivered using operative vaginal delivery, particularly from the midpelvis following a prolonged second stage3,4. However, less evidence is available for a fetus within the normal weight range who may be experiencing a prolonged second stage. Fetal presentation such as face, brow, or compound may also prolong the second stage of labor1. Face presentation with an adequate pelvis will usually result in vaginal delivery if mentum anterior. Fetal
position is also important in the second stage, particularly occiput posterior1. A prolonged second stage that is noted to have a deep transverse arrest is another indication for cesarean as no matter how long a woman is allowed to push, the fetus will not rotate in a way that allows for vaginal delivery1. Occiput posterior (OP) has also been shown to prolong labor. Chen et al, reported that among 20,201 vaginal deliveries, 5.4% or 1,087 neonates were delivered from OP positions5. Furthermore, the duration of second stage was approximately 60 minutes longer for nulliparous women when neonates delivered OP compared to those delivered in OA position. Importantly, this study did not look at maternal or neonatal morbidity associated with these longer durations for the second stage (see Table 3). Clinicians must consider how fetal weight, presentation, and position may impact the duration of the second stage, along with ongoing assessment of pelvimetry. Obesity and Second Stage Maternal obesity effects the first stage of labor, however, it has not been consistently shown to effect the length of the second stage of labor. A large, retrospective study of 118,978 nulliparous women revealed the time to progress from centimeter to centimeter increased with increasing body mass index6. There was no difference in second stage length for nulliparous women with or without an epidural 7. Meanwhile, the second stage length decreased as body mass increased for multiparous women6,7. Robison et al, also found in a secondary analysis of a multicenter trial of 5,341 women that increasing body mass index was not associated with second stage length8. Buhimschi et al, also showed intrauterine pressures in the second stage of labor were not different regardless of parity and body mass index9.
With a review of the maternal and fetal characteristics that may or may not impact the second stage of labor, below is a summary of the literature that supports a contemporary evidence-based management of the second stage of labor (Table 1). A central theme of this management requires clinicians to balance the immediate and long-term risks to both the women and the neonate. Table 2 highlights key maternal and neonatal morbidities associated with operative deliveries and should be used to compare with Table 3 which highlights the morbidities associated with a prolonged second stage of labor. Evidence-based management of the second stage of labor requires 1) continued progression/descent and 2) reassuring electronic fetal monitoring. If either are not occurring, the clinician must consider why the second stage is not progressing accordingly and weigh the risks-benefits of proceeding versus moving towards an operative delivery. Specific Evidence-Based Management of the Second Stage of Labor Expected Time to Delivery in the Second Stage Contemporary definition for the expected time to delivery in the second stage of labor are 3 hours for nulliparous and 2 hours for multiparous woman regardless of neuraxial analgesia. Labor curves and normality were historically based on Dr. Emanuel Friedman’s study of approximately 500 women10,11. While instrumental in our understanding of the natural progression of labor, labor curves were re-described in 2010 when Zhang et. al examined 62,414 term, spontaneous vaginal deliveries in a more contemporary obstetric population. This study redefined the active phase of labor as 6 cm and revealed a wide range of “normal” duration for labor that could result in a spontaneous vaginal delivery12. The average time for the second stage of labor was 1.1
hours for nulliparous women with an epidural and 0.6 hours without an epidural 12. Furthermore, at the 95th percentile of women who progressed to have a vaginal delivery, the second stage of labor was as long as 3.6 and 2.8 hours for nulliparous women with and without an epidural, respectively12. Similar, but shorter trends were observed among multiparous women. The expected time to delivery in the second stage of labor was stratified by parity and neuraxial analgesia (e.g. 4 and 3 hours for nulliparous women with and without an epidural respectively; 3 and 2 hours for multiparous women with and without an epidural). However, a Cochrane review of 38 randomized control trials (RCTs) including 9,658 women found that an epidural increased the second stage of labor with a mean difference of approximately 14 minutes. An RCT of 400 women by Shen et al, demonstrated that maintaining the infusion of epidural compared to placebo had no effect on duration of the second stage of labor.13 Additionally, an RCT by Wong et al, of 750 nulliparous women demonstrated a shorter duration of labor and better pain control with neuraxial analgesia compared to systemic analgesia14. Patients may benefit from turning down or up their neuraxial analgesia depending on the progression being made during the second stage (e.g. too much pain with contracted muscles may benefit from increased neuraxial analgesia versus inability to feel where to push may benefit from decreasing neuraxial analgesia). Clinicians should assess the effect of neuraxial analgesia during the second stage of labor on an individual patient basis. Immediate or delayed pushing The two most common approaches to the second stage of labor are either to allow for spontaneous descent (delayed pushing) or initiate pushing with uterine
contractions once cervical dilation is complete (immediate pushing). Frasier et al, conducted a large, multicenter trial of 1,862 nulliparous women with regional anesthesia and found that compared to immediate pushing, delayed pushing of 120 minutes led to higher rates of mid-pelvic procedures, maternal fever, and low neonatal pH. Furthermore, a systematic review and meta-analysis by Royal College of Obstetrics and Gynecology found that delayed pushing was associated with reduced pushing time, but longer second stage, increased maternal fevers and decreased rates of mid-pelvic procedures (e.g. rotational forceps). Additionally, there was no difference in operative vaginal deliveries, cesarean sections, and select maternal or neonatal outcomes. Importantly when interpreting these studies, mid-pelvic operative deliveries (e.g. rotational forceps) in the United States and contemporary obstetrics are less prevalent and do not reflect current management approaches. A meta-analysis by Tuuli et al, of twelve RCTs (1,584 immediate and 1,531 delayed pushing) focused the analysis on high-quality versus low-quality studies and found that among high quality studies, there was no difference between rates of vaginal or operative deliveries15. Delayed pushing was associated with a prolonged second stage of 56.92 minutes15. Furthermore, the effects on maternal and neonatal morbidity remained unknown. These questions were answered recently by Cahill et al, in a large, multicenter RCT of 2,414 women who were randomized to delayed pushing of 60 minutes or immediate16. There was no difference in rate of spontaneous vaginal delivery but the immediate pushing group had shorter mean duration of the second stage despite a longer mean duration of active pushing, lower rates of chorioamnionitis, fewer postpartum hemorrhages, and lower rates of neonatal acidemia and confirmed or
suspected sepsis16. Therefore, while there is no difference in the rate of spontaneous vaginal delivery, immediate pushing should be performed (not delayed pushing) in order to minimize the risk of maternal and neonatal morbidity. Maternal pushing technique Literature regarding the superiority or inferiority of maternal pushing techniques (e.g. three pushes per contraction, pushing with closed glottis / Valsalva, self-directed pushing) is limited. Lemos et. al performed a Cochrane review of 20 studies with a total of 815 women with either spontaneous pushing or directed pushing and found no difference in second stage length, perineal lacerations, episiotomy, APGAR scores, or NICU admissions17. Yet interestingly, most women who are told to start pushing without coaching will do so with an open glottis, allowing the air to escape from their lungs. Schaffer et. al conducted a RCT of coached and uncoached maternal pushing in the second stage and examined pelvic floor structure and function18. They found that urge to void and bladder capacity decreased in coached women18. This is the only study that suggests a potential harm to coached pushing. Finally, a meta-analysis of three RCTs of low-risk nulliparous women without an epidural found that Valsalva or pushing with a closed glottis shortened the second stage of labor19. Due to these limited data to support superiority of a particular pushing technique, clinicians should allow for each woman to use their preferred and most effective technique that results in fetal descent and decreases the length of time in the second stage of labor. Maternal Position There are a variety of maternal positions during pushing that have been studied with limited evidence to suggest a superior approach20. Observational studies
demonstrate that woman will select many different positions during labor on their own20. A recent Cochrane meta-analysis of RCTs found that upright or lateral positions compared with supine positions are associated with fewer abnormal fetal heart patterns relative risk (RR) 0.45, (95% CI 0.22-0.93), reduction in episiotomies RR 0.75, (95% CI 0.61-0.92), and decreased operative vaginal deliveries RR 0.75 (95% CI 0.66-0.86)21. Upright positions were associated with an increased risk of second degree perineal tears RR 1.20, (95% CI 1.00-1.41) and estimated blood loss greater than 500 mL RR 1.48, (95% CI 1.10-1.98)21. A 2017 RCT of nulliparous women pushing in upright compared to lying position demonstrated fewer vaginal births among women assigned to upright positioning RR 0.86, (95% CI 0.78-0.94)22. Provided this limited evidence, frequent position changes during the second stage to enhance maternal comfort and promote optimal fetal position can be supported as long as the maternal position allows for appropriate fetal monitoring and continued progression in the second stage. Clinicians and support staff may need to help guide patients to optimize or select the best pushing position and this may change as the second stage progresses. Continuous Support Person Woman who receive continuous support in addition to regular nursing care, were less likely to have a cesarean section, operative vaginal delivery, need for analgesia, newborn with a low 5-minute Apgar score and were more likely to have a shortened duration of labor and a higher satisfaction with the overall labor process23. Support by a non-medical person also improves the rate of spontaneous vaginal birth RR 1.08, (95% CI 1.04-1.12)24. Education of a family member or friend on how to be a labor support person was shown to be beneficial in a RCT of 600 nulliparous, low-income, low-risk
women as it led to a shorter duration of labor and higher Apgar scores at 1 and 5 minutes25. Integrating trained continuous support people in addition to labor and delivery nurses, midwives, and physicians who are often caring for more than one woman is beneficial and likely has a role in the optimal management of the second stage of labor26. Manual Rotation Occiput posterior and transverse fetal positions are associated with increased neonatal morbidity and risk of cesarean delivery1. Occiput posterior and occiput transverse make up 10-20% of fetal positions in the second stage of labor1. Le Ray et al, demonstrated that manual rotation was successful in 90.1% of those attempted and among those, 76.8% went on to deliver vaginally27. Le Ray also demonstrated that manual rotation led to a decreased rate of operative vaginal delivery27. The overall failure rate was 9.7% among 796 cases, and failed rotation was more common among women who were older, had an attempted rotation prior to 10 cm and had a manual rotation performed for failure to progress in the second stage27. Schaeffer et al, demonstrated among 742 women, 549 (74%) underwent a manual rotation from occiput posterior or occiput transverse and the rate of cesarean delivery was 2% compared with 34% if rotation failed p<0.00128. Additionally, multiparity and maternal age <35 were associated with successful manual rotation28. Schaeffer et al, further studied 731 woman who underwent manual rotation compared to 2,527 women who were expectantly managed and found decreased odds of cesarean section (8.6% vs 51.5%, p<0.001), postpartum hemorrhage (22.3% vs 33.1%, p<0.001), chorioamnionitis (8.6% vs 14.4%, p=0.02) and an overall number to avert one cesarean delivery was 4
pregnant women undergoing a manual rotation attempt during the second stage of labor29. Furthermore, among the 731 who underwent a manual rotation, there were no cases of umbilical cord prolapse and no difference in birth trauma or neonatal acidemia29. There was a shorter duration of the second stage of labor (90 minutes vs 141 minutes, p<0.001). Prior to moving to an operative delivery, it is reasonable to attempt a manual rotation of the fetus after appropriate counseling of the woman. Correct fetal position must be known and ultrasound may assist in verifying fetal position and has been shown to increase the success rate of manual rotation in a RCT30. Clinicians should also consider the above maternal and fetal factors that may influence the chance of a successful manual rotation. However, if the fetus does not easily manually rotate, this may be an indication that this management in the second stage of labor should be aborted and an operative delivery may be less morbid. Additionally other fetal characteristics such as size and position should be considered during patient selection. Operative Delivery The rate of operative vaginal deliveries being performed has decreased over the last two decades31. However, operative vaginal delivery in the management of the second stage of labor remains an excellent option for experienced and well-trained clinicians3,4. Indications for operative vaginal delivery include prolonged second stage of labor, suspicion of fetal compromise, and shortening the second stage of labor for maternal benefit3. Prerequisites for operative vaginal delivery include a cervix that is fully dilated and retracted, ruptured membranes, engagement of fetal head with determined position, an estimation of the fetal weight, an adequate pelvis for vaginal
delivery, adequate anesthesia, empty maternal bladder, informed consent of the patient including agreement to risk/benefits, and firm understanding that the alternative if an operative vaginal delivery fails is a cesarean delivery3. In a retrospective cohort of 2,181 nulliparous women who had a prolonged second stage of labor, 1,476 (68%) had an operative vaginal delivery and 705 (32%) had a cesarean delivery. Operative vaginal delivery was associated with decreased rates of chorioamnionitis (23% vs 28%, p=0.012), endometritis (2% vs 12%, p<0.001), severe postpartum hemorrhage (4% vs 9%, p<0.001) and need for blood transfusion (1% vs 3%, p<0.001) compared to cesarean delivery32. Neonates delivered by operative vaginal delivery had lower rates of NICU admissions and fetal acidemia32. Table 2 compares and contrasts maternal and fetal risks/morbidity associated with both operative vaginal delivery and cesarean delivery3,4,33-37. Overall, an operative vaginal delivery with forceps or vacuum is less morbid than a cesarean delivery and should be used by well-trained clinicians under the appropriate indications. Electronic fetal monitoring Assessment of fetal well-being with electronic fetal monitoring is essential when managing the second stage of labor. Occasionally during maternal pushes, monitoring may become challenging. Furthermore, higher body mass index also impacts the ability to monitor a fetus reliably38. In a prospective study of 67 women who were monitored with both external and internal fetal monitoring simultaneously, a higher signal loss was observed with external monitoring 10% vs 4%, p<0.0139. This is further demonstrated by Neilson et al, with examples of fetal heart rate decelerations that were subsequently found to be measurements of maternal heart rate40. Additionally, switching to internal
fetal monitoring revealed decelerations in fetal heart rate not being seen previously40. While these situations are rare, they are important considerations as the majority of fetal heart rate patterns in the second stage of labor are category II tracings.41 Increasing evidence also demonstrates that not all category II tracings carry the same fetal risk 42 and internal monitoring may help guide clinicians in accurately assessing fetal status during the second stage. If a clinician is unsure of how to interpret the electronic fetal monitoring during the second stage of labor, placement of a fetal scalp electrode may be indicated and appropriate. Decreasing perineal tears Perineal management interventions in the second stage of labor have been well studied and include maternal perineal massage, manual perineal support, and warm compress43. Of these, perineal massage and warm compress have the most evidence for management in the second stage of labor. A meta-analysis of 2,147 women demonstrated perineal massage during the second stage of labor reduced third-degree and fourth-degree tears when compared with a hands off approach risk ratio 0.52, (95% CI, 0.29-0.94) but did not impact the rate of intact perineum at delivery43. Studies regarding manual support of the perineum at delivery are difficult to interpret as the specific techniques (e.g. flexion, Ritgen, etc.) used to support the perineum are poorly described and variable. A meta-analysis of three RCTs included 6,647 women to manual support compared to expectant did not reduce the rates of obstetric and anal sphincter (OASIS) rates. However, a meta-analysis of observational studies of 75,744 women show a significant reduction in OASIS tears RR 0.45, (95% CI, 0.40-0.50)44 with perineal support. Additional well designed studies that clarify the specific techniques for
manual support of the perineum are needed to clarify if there is a true benefit. A metaanalysis of warm compress during the second stage of labor in 1,525 women demonstrate a reduction in third and fourth degree lacerations RR 0.48, (95% CI, 0.280.84) but no change in having an intact perineum at delivery43. In summary, perineal massage and warm compress appear to decrease the risk of more severe (e.g. 3rd and 4th degree) lacerations but do not increase the probability of delivering with an intact perineum. Clinicians may use perineal massage and warm compress during the second stage of labor. Further research is needed to clarify if and which manual perineal support may beneficial during the second stage of labor. How long is too long for second stage? This question is difficult to assess as it requires clinicians to integrate multiple related factors and consider the risk-benefit associated with operative delivery versus a prolonged second stage of labor. More specifically, clinicians must consider if the risk of maternal and neonatal morbidity associated with a prolonged second stage of labor outweigh that of an operative delivery. Table 2 and 3 highlight the established risks based on the literature below. A recent systematic review by Gimovsky et al, of 5,350 nulliparous women with a prolonged second stage of labor (i.e. >3 hours) found that 80.2% of the study population progress to have a vaginal delivery45. Gimovsky et al, further demonstrated in a RCT of 78 nulliparous women assigned to 1 additional hour for the second stage of labor that the number needed to prevent 1 cesarean delivery was 4.2 46. While promising, thinking critically about maternal and neonatal morbidity with prolonged second stage is essential. Existing evidence does support that there is a duration where the risk of
maternal/neonatal morbidity outweigh the chance of a successful vaginal delivery, but that exact time has not been established. A secondary analysis of a multicenter randomized study of 4,126 nulliparous women showed the length of the second stage was not associated with 5-minute APGAR scores of <4, umbilical artery pH <7.0, neonatal intubation, admission to neonatal intensive care unit, or neonatal sepsis but did have increased maternal morbidity (i.e. puerperal infection, higher degree laceration and postpartum hemorrhage)47. Le Ray et. al performed a retrospective study of 1,862 nulliparous women and showed that relative to the first hour, the chance of a spontaneous vaginal delivery of a newborn without signs of asphyxia decreased significantly every hour (1 to 2 hour odds ratio OR 0.4, (95% CI, 0.3-0.6); 2 to 3 hour OR 0.1, (95% CI, 0.09-0.2); and >3 hour OR 0.03, (95% CI, 0.02-0.05))27. Furthermore, in a population-based cohort of 121,517 women by Allen at. al, there was an increased risk of maternal obstetric trauma, postpartum hemorrhage, puerperal febrile morbidity as well as low 5-minute Apgar score, birth depression, and admission to neonatal intensive care unit with prolonged second stage of labor35. Finally, Laughon et. al performed a retrospective cohort of 43,810 nulliparous and 59,605 multiparous women comparing prolonged second stage to those women with labor curves within the guidelines and found significant maternal morbidity (e.g. chorioamnionitis, 3rd and 4th degree laceration) and neonatal morbidity (sepsis, asphyxia, and perinatal mortality)48. Additionally, a retrospective of 5,158 multiparous women with a second stage of 3 hours or more had increased risk of operative delivery, peripartum morbidity, and undesirable neonatal outcomes34. After > 3 hour second stage of labor duration, only 1 in 4 nulliparous
women47 and 1 in 3 multiparous women will give birth spontaneously while 30-50% will require operative delivery to give birth vaginally once these threshold are reached 34. Collectively, longer time in the second stage is associated with increased risk of both maternal and neonatal morbidity, decreasing probability of spontaneous vaginal delivery and should be closely monitored and assessed. Figure 1 presents a proposed algorithm for clinicians to use when assessing the second stage of labor and weighing the maternal and neonatal risk associated with operative delivery and prolonged second stage of labor. Clinicians must use this information critically to manage the second stage of labor. Further research is also needed to help define other fetal or labor characteristics that may aid clinicians in deciding that the second stage of labor has gone on for too long. Key evidence-based management of the second stage of labor In summary, the literature supports several evidence-based management strategies for the second stage of labor that obstetricians may utilize (Table 1). Evidence-based management of the second stage of labor should include, immediate pushing at the start of the second stage, expected delivery within 2 hours for multiparous and 3 hours for nulliparous women in the second stage with no clear defined maximum time but established neonatal and maternal morbidities with longer duration, utilization of operative vaginal delivery and manual rotation alongside ultrasound in trained clinicians when clinically appropriate to minimize maternal and neonatal morbidity, use of warm compress and perineal massage to decrease risk for third- and fourth-degree tears, use of a continuous support person outside of regular nursing care, freedom for women to choose pushing technique and position if progress
is being made and fetal monitoring is not impeded, and finally, use of internal fetal monitoring if clinicians are unable to safely monitor the fetus. At the core of second stage management, clinicians must be assessing for both progression and descent and reassuring fetal status in an on-going manner (Figure 1). Furthermore, if the second stage of labor is not progressing, clinicians may need to individualize their management techniques to each women (e.g. trial of turning down an epidural in a women who is unable to feel where she should push) while considering the risks and benefits of continuation in the second stage, operative vaginal delivery, and cesarean delivery. DISCLOSURE STATEMENT The authors have no financial disclosures.
TABLE AND FIGURES Table 1: Summary of key evidence-based management of second stage of labor Management Recommendation Specific length of time spent in second stage of labor which all women should undergo operative delivery has not been established Immediate pushing should begin following the start of the second stage to decrease maternal and neonatal morbidity Before diagnosing arrest of labor in second stage, if maternal and fetal conditions permit, all for following: -2 hours pushing in multiparous -3 hours of pushing in nulliparous women Longer durations may be appropriate on individualized basis (e.g. epidural analgesia, fetal malposition) as long as progress is occurring Operative vaginal delivery in second stage of labor by experienced and well-trained physician should be considered safe, acceptable alternative to cesarean delivery. Training in, ongoing maintenance of the practical skills related to operative vaginal delivery should be encouraged Manual rotation of fetal occiput in setting of fetal malposition is reasonable interventions to consider before moving to operative delivery. Ultrasound should be used in conjunction to increase success rates. To safely prevent cesarean deliveries in setting of malposition, it is important to assess fetal position in second stage of labor, particularly in setting of abnormal fetal decent Warm compress and perineal massage may be used to decrease the risk of third-degree and fourth-degree lacerations; however, it has no effect on increasing the rate of an intact perineum at delivery Women may assume any birthing position and use any pushing technique they request as long as progress is being made in the second stage of labor Continuous support person in addition to regular nursing care
Clinicians should consider a fetal scalp electrode or internal monitoring if they are unable to reliably monitor the fetus during the second stage of labor
Grade of recommendation 1C Strong recommendation, lowquality evidence 1B Strong recommendation, moderate-quality evidence 1B Strong recommendation, moderate-quality evidence
1B Strong recommendation, moderate-quality evidence
1B Strong recommendation, moderate-quality evidence
1B Strong recommendation, moderate-quality evidence 1C Strong recommendation, lowquality evidence 1C Strong recommendation, lowquality evidence 2C Weak recommendation, low quality evidence
Use of pelvimetry to assess progression in the second stage
2C Weak recommendation, lo quality evidence
Table 2: Maternal and neonatal morbidities by operative delivery
Outcome Maternal Morbidity3 Short-term risks
Long-term risk
Operative Delivery Vaginal operative delivery
Increased risk of third- or fourth-degree tears, highest with forceps-assisted Increases risk of anal incontinence at 6 weeks No difference in bowel/urinary dysfunction at 5 years postpartum compared to vaginal delivery
Neonatal Morbidity33,37 Brachial plexus 0.17-0.43% vacuum injury 0.25-0.56% forceps Facial injury
0.05% vacuum
Cesarean delivery
Hemorrhage Infection Prolonged healing Venous thrombosis
Increased risk for repeat cesarean delivery Increased risk of placental abnormalities Increased health care costs 0.01-0.04%
0.03-0.05%
0.45% forceps
Mechanical ventilation Shoulder dystocia Intracranial hemorrhage Neurologic complications Combined neurologic
Forceps associated with an increased relative risk 5.10, (95% CI, 1.12-23.25) 0.39% vacuum
0.71-1.03%
0.45% forceps 1-2%4
0%
1:664-860
N/A
1:220-385
N/A
0.45% vacuum
0.44%
(seizure, IVH, subdural hemorrhage)
5-minute Apgar score <7 Death
0.26% forceps Forceps-assisted vaginal delivery reduced risk odds ratio 0.60, (95% CI, 0.40-0.90) compared to vacuum-assisted or cesarean delivery 0.76% vacuum 0.98% 0.43% forceps 0.3:1000 vacuum
0.8:1000
0.5:1000 forceps
Table 3. Summarization of maternal and neonatal morbidity associated with prolonged second stage of labor Summary: Increasing maternal and neonatal morbidity, regardless of parity, with prolonged second stage of labor Study, type Maternal Outcomes Neonatal Outcomes and sample size Rouse et. al47 Decreasing rate of spontaneous Increased odds of admission to NICU OR (FOX trial) vaginal delivery as duration 1.4 Retrospective increased (85% <1 hour vs 9% > 5 Increased odds of brachial plexus injury analysis, hours) OR 1.78 (95% CI, 1.08-2.78) 4126 women Increasing rate of chorioamnionitis who reached 3.9% second stage Increasing rate of third- or fourthof labor degree lacerations 8.7% Increasing rate of uterine atony 3.9% Le Ray et. al Compared to 1 hour, increased risk Compared to first hour, chance of a 27 (PEOPLE spontaneous vaginal delivery of infant of postpartum hemorrhage trial) 2-3 hours aOR 1.6 (95% CI, 1.0-2.5) without signs of asphyxia decreased every Secondary > 3 hours aOR 2.5 (95% CI, 1.5-4.1) hour analysis of 1-2 hour aOR 0.4 (95% CI, 0.3-0.6) Intrapartum fever randomized 2-3 hour aOR 0.1 (95% CI, 0.09-0.2) <1 hour 3.3% control trial, >3 hour aOR 0.03 (95% CI, 0.02-0.05) 1-2 hr 6.3%
1,862 women Allen et. al35 Populationbased cohort, 121,517 women
2-3 h 8.8% >3 hours 12.3% 30-fold increased risk of operative delivery if pushing >3 hours Increased risk maternal obstetric trauma 2-3 hours aRR 1.45 (95% CI, 1.321.60) 3-4 hours aRR 1.84 (95% CI, 1.652.06) 4-5 hours aRR 2.07 (95% CI, 1.822.36) >5 hours aRR 2.18 (95% CI, 1.902.50) for nulliparous women and 1-2 hours aRR 1.30 (95% CI, 1.051.62) 2-3 hours aRR 2.01 (95% CI, 1.512.68) >3 hours aRR 1.96 (95% CI, 1.452.67) for multiparous women Postpartum hemorrhage 2-3 hours aRR 1.30 (95% CI, 1.191.43) 3-4 hours aRR 1.53 (95% CI, 1.371.72), 4-5 hours aRR 1.59 (95% CI, 1.391.82), and >5 hours aRR 1.75 (95% CI, 1.522.02) for nulliparous women and 1-2 hours aRR 1.18 (95% CI, 1.021.35), 2-3 hours aRR 1.07 (95% CI, 0.831.37), and >3 hours aRR 1.37 (95% CI, 1.061.77) for multiparous women Puerperal febrile morbidity 2-3 hours aRR 1.30 (95% CI, 1.131.50), 3-4 hours aRR 1.63 (95% CI, 1.391.92), 4-5 hours aRR 1.51 (95% CI, 1.251.83), >5 hours aRR 1.49 (95% CI, 1.21-
Low 5-minute Apgar score 2-3 hours aRR 1.33 (95% CI, 1.07-1.64), 3-4 hours aRR 1.36 (95% CI, 1.04-1.77) for neonates of nulliparous women and 1-2 hours aRR 1.75 (95% CI, 1.23-2.51), 2-3 hours aRR 2.64 (95% CI, 1.59-4.37), and >3 hours aRR 2.24 (95% CI, 1.25-4.0) for neonates of multiparous women Birth depression 2-3 hours aRR 1.68 (95% CI, 1.43-1.98), 3-4 hours aRR 1.59 (95% CI, 1.29-1.97), 4-5 hours aRR 1.93 (95% CI, 1.51-2.47), and >5 hours aRR 1.96 (95% CI, 1.51-2.55) for neonates of nulliparous women and 1-2 hours aRR 1.27 (95% CI, 0.95-1.70), 2-3 hours aRR 1.76 (95% CI, 1.15-2.71), and >3 hours aRR 1.68 (95% CI, 1.05-2.70) for neonates born to multiparous women Admission to neonatal intensive care unit 2-3 hours aRR 1.43 (95% CI, 1.30-1.57), 3-4 hours aRR 1.94 (95% CI, 1.74-2.16), 4-5 hours aRR 2.10 (95% CI, 1.84-2.40), and >5 hours aRR 1.99 (95% CI, 1.72-2.30) for neonates born to nulliparous women and 1-2 hours aRR 1.35 (95% CI, 1.17-1.56), 2-3 hours aRR 1.50 (95% CI, 1.19-1.90) and >3 hours aRR 1.55 (95% CI, 1.20-2.0) for neonates born to multiparous women Composite perinatal morbidity 2-3 hours 1.52 (95% CI, 1.41-1.64), 3-4 hours 1.74 (95% CI, 1.59-1.91), 4-5 hours 1.94 (95% CI, 1.74-2.17), and >5 hours 1.85 (95% CI, 1.64-2.08) for neonates born to nulliparous women and
Laughon et. 48 al Retrospective cohort, 43,810 nuliparous & 59,605 multiparous singleton deliveries
1.84) for nulliparous women and 1-2 hours aRR 1.78 (95% CI, 1.382.29), 2-3 hours aRR 1.73 (95% CI, 1.152.58) and >3 hours aRR 3.17 (95% CI, 2.194.58) for multiparous women Composite maternal morbidity 2-3 hours aRR 1.82 (95% CI, 1.721.94), 3-4 hours aRR2.51 (95% CI, 2.332.70), 4-5 hours aRR 2.94 (95% CI, 2.693.22), and >5 hours RR 3.29 (95% CI, 2.99-3.61) for nulliparous women and 1-2 hours aRR 1.28 (95% CI, 1.141.43), 2-3 hours aRR 1.46 (95% CI, 1.221.75), and >3 hours aRR 1.73 (95% CI, 1.442.10) for multiparous women Composite maternal morbidity higher nulliparous women with an epidural with prolonged second stage aOR 1.42 (95% CI, 1.25-1.62) Increased rates of chorioamnionitis aOR 3.01 (95% CI, 2.65-3.43) nullips with epidural & aOR 3.18 (95% CI, 2.34-4.33) nullips without epidural aOR 4.78 (95% CI, 3.46-6.61) & aOR 2.34 (95% CI, 1.16-4.72) for multips with and without epidural Endometritis nullips with epidural aOR 3.21 (95% CI, 2.25-4.57) Wound separation nullips with epidural aOR 12.13 (95% CI, 3.6340.46) Postpartum hemorrhage nullips with epidural aOR 1.50 (95% CI, 1.27-1.78) Increased rates of third- or fourthdegree lacerations
1-2 hours 1.38 (95% CI, 1.23-1.56), 2-3 hours 1.64 (95% CI, 1.35-1.98), and >3 hours 1.42 (95% CI, 1.14-1.76) for women born to multiparous women
Sepsis nulliparous women with epidural aOR 2.08 (95% CI, 1.60-2.70) and without epidural aOR 2.34 (95% CI, 1.28-4.27) Asphyxia nulliparous with epidural aOR 2.39 (95% CI, 1.22-4.66) Perinatal mortality nulliparous women without epidural aOR 5.92 (95% CI, 1.4324.51) and aOR 6.34 (95% CI, 1.32-30.34) multiparous women
aOR 1.80 (95% CI, 1.58-2.05) nullips with epidural and aOR 1.78 (95% CI, 1.43-2.22) nullips without epidural, aOR 3.85 (95% CI, 2.65-5.60) & aOR 3.20 (95% CI, 1.71-5.99) multips with and without epidural
Figure 1: Second stage management algorithm
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Evidence-Based Management of the Second Stage of Labor Brock E. Polnaszek MD , Alison G. Cahill MD, MSCI PII: DOI: Reference:
S0146-0005(19)30150-8 https://doi.org/10.1016/j.semperi.2019.151213 YSPER 151213
To appear in:
Seminars in Perinatology
Please cite this article as: Brock E. Polnaszek MD , Alison G. Cahill MD, MSCI , EvidenceBased Management of the Second Stage of Labor, Seminars in Perinatology (2019), doi: https://doi.org/10.1016/j.semperi.2019.151213
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TITLE PAGE Title: Evidence-Based Management of the Second Stage of Labor Authors: Brock E. Polnaszek, MD & Alison G. Cahill, MD, MSCI Washington University in Saint Louis School of Medicine, Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine. Saint Louis, MO, United States of America Corresponding Author: Brock E. Polnaszek, Department of Obstetrics and Gynecology, Washington University in Saint Louis School of Medicine, 901 Forest Park Avenue. St. Louis, MO 63108. Phone: 314-565-3765; Fax: 314-747-1490, Email: [email protected]
ABSTRACT The second stage of labor is defined as the time from complete dilation of the cervix to delivery of the fetus. The objective of this seminar is to provide a contemporary, evidence-based approach to management of the second stage of labor. This seminar reviews background maternal and fetal characteristics that impact the duration of the second stage of labor, the recommended evidence-based management (e.g. immediate pushing, manual rotation, operative vaginal delivery), and the maternal/neonatal morbidity clinicians must consider when deciding between operative delivery and a prolonged second stage of labor.
TEXT Fetopelvic proportion and Second Stage Characteristics of the maternal pelvis, fetus, and usually both may impact the progression of the second stage of labor1. Android, anthropoid, gynecoid, and platypelloid pelvic types all influence the way the fetus must progress in labor. Pelvic contractions at the inlet, midpelvis, outlet and/or a combination have been explored based on anatomical measurements. Mengert and Kaltreider showed that the incidence of difficult deliveries was increased when either the shortest anteroposterior diameter was <10 cm or the greatest transverse diameter was <12 cm2. However, no imaging or manual measurements are predictive of a failed vaginal delivery. Pelvimetry is a clinical assessment by obstetric providers that should be used throughout the second stage of labor starting with an assessment of the maternal pelvis and the birth canal the fetus must navigate. Specific fetal characteristics such as size, position, and presentation may impact the progression of the second stage of labor as well1. With an estimated fetal weight of 4,500 grams or more, a prolonged or arrest of descent during the second stage is an indication for cesarean delivery3,4. Research has consistently demonstrated an increased risk of shoulder dystocia when a macrosomic fetus is delivered using operative vaginal delivery, particularly from the midpelvis following a prolonged second stage3,4. However, less evidence is available for a fetus within the normal weight range who may be experiencing a prolonged second stage. Fetal presentation such as face, brow, or compound may also prolong the second stage of labor1. Face presentation with an adequate pelvis will usually result in vaginal delivery if mentum anterior. Fetal
position is also important in the second stage, particularly occiput posterior1. A prolonged second stage that is noted to have a deep transverse arrest is another indication for cesarean as no matter how long a woman is allowed to push, the fetus will not rotate in a way that allows for vaginal delivery1. Occiput posterior (OP) has also been shown to prolong labor. Chen et al, reported that among 20,201 vaginal deliveries, 5.4% or 1,087 neonates were delivered from OP positions5. Furthermore, the duration of second stage was approximately 60 minutes longer for nulliparous women when neonates delivered OP compared to those delivered in OA position. Importantly, this study did not look at maternal or neonatal morbidity associated with these longer durations for the second stage (see Table 3). Clinicians must consider how fetal weight, presentation, and position may impact the duration of the second stage, along with ongoing assessment of pelvimetry. Obesity and Second Stage Maternal obesity effects the first stage of labor, however, it has not been consistently shown to effect the length of the second stage of labor. A large, retrospective study of 118,978 nulliparous women revealed the time to progress from centimeter to centimeter increased with increasing body mass index6. There was no difference in second stage length for nulliparous women with or without an epidural 7. Meanwhile, the second stage length decreased as body mass increased for multiparous women6,7. Robison et al, also found in a secondary analysis of a multicenter trial of 5,341 women that increasing body mass index was not associated with second stage length8. Buhimschi et al, also showed intrauterine pressures in the second stage of labor were not different regardless of parity and body mass index9.
With a review of the maternal and fetal characteristics that may or may not impact the second stage of labor, below is a summary of the literature that supports a contemporary evidence-based management of the second stage of labor (Table 1). A central theme of this management requires clinicians to balance the immediate and long-term risks to both the women and the neonate. Table 2 highlights key maternal and neonatal morbidities associated with operative deliveries and should be used to compare with Table 3 which highlights the morbidities associated with a prolonged second stage of labor. Evidence-based management of the second stage of labor requires 1) continued progression/descent and 2) reassuring electronic fetal monitoring. If either are not occurring, the clinician must consider why the second stage is not progressing accordingly and weigh the risks-benefits of proceeding versus moving towards an operative delivery. Specific Evidence-Based Management of the Second Stage of Labor Expected Time to Delivery in the Second Stage Contemporary definition for the expected time to delivery in the second stage of labor are 3 hours for nulliparous and 2 hours for multiparous woman regardless of neuraxial analgesia. Labor curves and normality were historically based on Dr. Emanuel Friedman’s study of approximately 500 women10,11. While instrumental in our understanding of the natural progression of labor, labor curves were re-described in 2010 when Zhang et. al examined 62,414 term, spontaneous vaginal deliveries in a more contemporary obstetric population. This study redefined the active phase of labor as 6 cm and revealed a wide range of “normal” duration for labor that could result in a spontaneous vaginal delivery12. The average time for the second stage of labor was 1.1
hours for nulliparous women with an epidural and 0.6 hours without an epidural 12. Furthermore, at the 95th percentile of women who progressed to have a vaginal delivery, the second stage of labor was as long as 3.6 and 2.8 hours for nulliparous women with and without an epidural, respectively12. Similar, but shorter trends were observed among multiparous women. The expected time to delivery in the second stage of labor was stratified by parity and neuraxial analgesia (e.g. 4 and 3 hours for nulliparous women with and without an epidural respectively; 3 and 2 hours for multiparous women with and without an epidural). However, a Cochrane review of 38 randomized control trials (RCTs) including 9,658 women found that an epidural increased the second stage of labor with a mean difference of approximately 14 minutes. An RCT of 400 women by Shen et al, demonstrated that maintaining the infusion of epidural compared to placebo had no effect on duration of the second stage of labor.13 Additionally, an RCT by Wong et al, of 750 nulliparous women demonstrated a shorter duration of labor and better pain control with neuraxial analgesia compared to systemic analgesia14. Patients may benefit from turning down or up their neuraxial analgesia depending on the progression being made during the second stage (e.g. too much pain with contracted muscles may benefit from increased neuraxial analgesia versus inability to feel where to push may benefit from decreasing neuraxial analgesia). Clinicians should assess the effect of neuraxial analgesia during the second stage of labor on an individual patient basis. Immediate or delayed pushing The two most common approaches to the second stage of labor are either to allow for spontaneous descent (delayed pushing) or initiate pushing with uterine
contractions once cervical dilation is complete (immediate pushing). Frasier et al, conducted a large, multicenter trial of 1,862 nulliparous women with regional anesthesia and found that compared to immediate pushing, delayed pushing of 120 minutes led to higher rates of mid-pelvic procedures, maternal fever, and low neonatal pH. Furthermore, a systematic review and meta-analysis by Royal College of Obstetrics and Gynecology found that delayed pushing was associated with reduced pushing time, but longer second stage, increased maternal fevers and decreased rates of mid-pelvic procedures (e.g. rotational forceps). Additionally, there was no difference in operative vaginal deliveries, cesarean sections, and select maternal or neonatal outcomes. Importantly when interpreting these studies, mid-pelvic operative deliveries (e.g. rotational forceps) in the United States and contemporary obstetrics are less prevalent and do not reflect current management approaches. A meta-analysis by Tuuli et al, of twelve RCTs (1,584 immediate and 1,531 delayed pushing) focused the analysis on high-quality versus low-quality studies and found that among high quality studies, there was no difference between rates of vaginal or operative deliveries15. Delayed pushing was associated with a prolonged second stage of 56.92 minutes15. Furthermore, the effects on maternal and neonatal morbidity remained unknown. These questions were answered recently by Cahill et al, in a large, multicenter RCT of 2,414 women who were randomized to delayed pushing of 60 minutes or immediate16. There was no difference in rate of spontaneous vaginal delivery but the immediate pushing group had shorter mean duration of the second stage despite a longer mean duration of active pushing, lower rates of chorioamnionitis, fewer postpartum hemorrhages, and lower rates of neonatal acidemia and confirmed or
suspected sepsis16. Therefore, while there is no difference in the rate of spontaneous vaginal delivery, immediate pushing should be performed (not delayed pushing) in order to minimize the risk of maternal and neonatal morbidity. Maternal pushing technique Literature regarding the superiority or inferiority of maternal pushing techniques (e.g. three pushes per contraction, pushing with closed glottis / Valsalva, self-directed pushing) is limited. Lemos et. al performed a Cochrane review of 20 studies with a total of 815 women with either spontaneous pushing or directed pushing and found no difference in second stage length, perineal lacerations, episiotomy, APGAR scores, or NICU admissions17. Yet interestingly, most women who are told to start pushing without coaching will do so with an open glottis, allowing the air to escape from their lungs. Schaffer et. al conducted a RCT of coached and uncoached maternal pushing in the second stage and examined pelvic floor structure and function18. They found that urge to void and bladder capacity decreased in coached women18. This is the only study that suggests a potential harm to coached pushing. Finally, a meta-analysis of three RCTs of low-risk nulliparous women without an epidural found that Valsalva or pushing with a closed glottis shortened the second stage of labor19. Due to these limited data to support superiority of a particular pushing technique, clinicians should allow for each woman to use their preferred and most effective technique that results in fetal descent and decreases the length of time in the second stage of labor. Maternal Position There are a variety of maternal positions during pushing that have been studied with limited evidence to suggest a superior approach20. Observational studies
demonstrate that woman will select many different positions during labor on their own20. A recent Cochrane meta-analysis of RCTs found that upright or lateral positions compared with supine positions are associated with fewer abnormal fetal heart patterns relative risk (RR) 0.45, (95% CI 0.22-0.93), reduction in episiotomies RR 0.75, (95% CI 0.61-0.92), and decreased operative vaginal deliveries RR 0.75 (95% CI 0.66-0.86)21. Upright positions were associated with an increased risk of second degree perineal tears RR 1.20, (95% CI 1.00-1.41) and estimated blood loss greater than 500 mL RR 1.48, (95% CI 1.10-1.98)21. A 2017 RCT of nulliparous women pushing in upright compared to lying position demonstrated fewer vaginal births among women assigned to upright positioning RR 0.86, (95% CI 0.78-0.94)22. Provided this limited evidence, frequent position changes during the second stage to enhance maternal comfort and promote optimal fetal position can be supported as long as the maternal position allows for appropriate fetal monitoring and continued progression in the second stage. Clinicians and support staff may need to help guide patients to optimize or select the best pushing position and this may change as the second stage progresses. Continuous Support Person Woman who receive continuous support in addition to regular nursing care, were less likely to have a cesarean section, operative vaginal delivery, need for analgesia, newborn with a low 5-minute Apgar score and were more likely to have a shortened duration of labor and a higher satisfaction with the overall labor process23. Support by a non-medical person also improves the rate of spontaneous vaginal birth RR 1.08, (95% CI 1.04-1.12)24. Education of a family member or friend on how to be a labor support person was shown to be beneficial in a RCT of 600 nulliparous, low-income, low-risk
women as it led to a shorter duration of labor and higher Apgar scores at 1 and 5 minutes25. Integrating trained continuous support people in addition to labor and delivery nurses, midwives, and physicians who are often caring for more than one woman is beneficial and likely has a role in the optimal management of the second stage of labor26. Manual Rotation Occiput posterior and transverse fetal positions are associated with increased neonatal morbidity and risk of cesarean delivery1. Occiput posterior and occiput transverse make up 10-20% of fetal positions in the second stage of labor1. Le Ray et al, demonstrated that manual rotation was successful in 90.1% of those attempted and among those, 76.8% went on to deliver vaginally27. Le Ray also demonstrated that manual rotation led to a decreased rate of operative vaginal delivery27. The overall failure rate was 9.7% among 796 cases, and failed rotation was more common among women who were older, had an attempted rotation prior to 10 cm and had a manual rotation performed for failure to progress in the second stage27. Schaeffer et al, demonstrated among 742 women, 549 (74%) underwent a manual rotation from occiput posterior or occiput transverse and the rate of cesarean delivery was 2% compared with 34% if rotation failed p<0.00128. Additionally, multiparity and maternal age <35 were associated with successful manual rotation28. Schaeffer et al, further studied 731 woman who underwent manual rotation compared to 2,527 women who were expectantly managed and found decreased odds of cesarean section (8.6% vs 51.5%, p<0.001), postpartum hemorrhage (22.3% vs 33.1%, p<0.001), chorioamnionitis (8.6% vs 14.4%, p=0.02) and an overall number to avert one cesarean delivery was 4
pregnant women undergoing a manual rotation attempt during the second stage of labor29. Furthermore, among the 731 who underwent a manual rotation, there were no cases of umbilical cord prolapse and no difference in birth trauma or neonatal acidemia29. There was a shorter duration of the second stage of labor (90 minutes vs 141 minutes, p<0.001). Prior to moving to an operative delivery, it is reasonable to attempt a manual rotation of the fetus after appropriate counseling of the woman. Correct fetal position must be known and ultrasound may assist in verifying fetal position and has been shown to increase the success rate of manual rotation in a RCT30. Clinicians should also consider the above maternal and fetal factors that may influence the chance of a successful manual rotation. However, if the fetus does not easily manually rotate, this may be an indication that this management in the second stage of labor should be aborted and an operative delivery may be less morbid. Additionally other fetal characteristics such as size and position should be considered during patient selection. Operative Delivery The rate of operative vaginal deliveries being performed has decreased over the last two decades31. However, operative vaginal delivery in the management of the second stage of labor remains an excellent option for experienced and well-trained clinicians3,4. Indications for operative vaginal delivery include prolonged second stage of labor, suspicion of fetal compromise, and shortening the second stage of labor for maternal benefit3. Prerequisites for operative vaginal delivery include a cervix that is fully dilated and retracted, ruptured membranes, engagement of fetal head with determined position, an estimation of the fetal weight, an adequate pelvis for vaginal
delivery, adequate anesthesia, empty maternal bladder, informed consent of the patient including agreement to risk/benefits, and firm understanding that the alternative if an operative vaginal delivery fails is a cesarean delivery3. In a retrospective cohort of 2,181 nulliparous women who had a prolonged second stage of labor, 1,476 (68%) had an operative vaginal delivery and 705 (32%) had a cesarean delivery. Operative vaginal delivery was associated with decreased rates of chorioamnionitis (23% vs 28%, p=0.012), endometritis (2% vs 12%, p<0.001), severe postpartum hemorrhage (4% vs 9%, p<0.001) and need for blood transfusion (1% vs 3%, p<0.001) compared to cesarean delivery32. Neonates delivered by operative vaginal delivery had lower rates of NICU admissions and fetal acidemia32. Table 2 compares and contrasts maternal and fetal risks/morbidity associated with both operative vaginal delivery and cesarean delivery3,4,33-37. Overall, an operative vaginal delivery with forceps or vacuum is less morbid than a cesarean delivery and should be used by well-trained clinicians under the appropriate indications. Electronic fetal monitoring Assessment of fetal well-being with electronic fetal monitoring is essential when managing the second stage of labor. Occasionally during maternal pushes, monitoring may become challenging. Furthermore, higher body mass index also impacts the ability to monitor a fetus reliably38. In a prospective study of 67 women who were monitored with both external and internal fetal monitoring simultaneously, a higher signal loss was observed with external monitoring 10% vs 4%, p<0.0139. This is further demonstrated by Neilson et al, with examples of fetal heart rate decelerations that were subsequently found to be measurements of maternal heart rate40. Additionally, switching to internal
fetal monitoring revealed decelerations in fetal heart rate not being seen previously40. While these situations are rare, they are important considerations as the majority of fetal heart rate patterns in the second stage of labor are category II tracings.41 Increasing evidence also demonstrates that not all category II tracings carry the same fetal risk 42 and internal monitoring may help guide clinicians in accurately assessing fetal status during the second stage. If a clinician is unsure of how to interpret the electronic fetal monitoring during the second stage of labor, placement of a fetal scalp electrode may be indicated and appropriate. Decreasing perineal tears Perineal management interventions in the second stage of labor have been well studied and include maternal perineal massage, manual perineal support, and warm compress43. Of these, perineal massage and warm compress have the most evidence for management in the second stage of labor. A meta-analysis of 2,147 women demonstrated perineal massage during the second stage of labor reduced third-degree and fourth-degree tears when compared with a hands off approach risk ratio 0.52, (95% CI, 0.29-0.94) but did not impact the rate of intact perineum at delivery43. Studies regarding manual support of the perineum at delivery are difficult to interpret as the specific techniques (e.g. flexion, Ritgen, etc.) used to support the perineum are poorly described and variable. A meta-analysis of three RCTs included 6,647 women to manual support compared to expectant did not reduce the rates of obstetric and anal sphincter (OASIS) rates. However, a meta-analysis of observational studies of 75,744 women show a significant reduction in OASIS tears RR 0.45, (95% CI, 0.40-0.50)44 with perineal support. Additional well designed studies that clarify the specific techniques for
manual support of the perineum are needed to clarify if there is a true benefit. A metaanalysis of warm compress during the second stage of labor in 1,525 women demonstrate a reduction in third and fourth degree lacerations RR 0.48, (95% CI, 0.280.84) but no change in having an intact perineum at delivery43. In summary, perineal massage and warm compress appear to decrease the risk of more severe (e.g. 3rd and 4th degree) lacerations but do not increase the probability of delivering with an intact perineum. Clinicians may use perineal massage and warm compress during the second stage of labor. Further research is needed to clarify if and which manual perineal support may beneficial during the second stage of labor. How long is too long for second stage? This question is difficult to assess as it requires clinicians to integrate multiple related factors and consider the risk-benefit associated with operative delivery versus a prolonged second stage of labor. More specifically, clinicians must consider if the risk of maternal and neonatal morbidity associated with a prolonged second stage of labor outweigh that of an operative delivery. Table 2 and 3 highlight the established risks based on the literature below. A recent systematic review by Gimovsky et al, of 5,350 nulliparous women with a prolonged second stage of labor (i.e. >3 hours) found that 80.2% of the study population progress to have a vaginal delivery45. Gimovsky et al, further demonstrated in a RCT of 78 nulliparous women assigned to 1 additional hour for the second stage of labor that the number needed to prevent 1 cesarean delivery was 4.2 46. While promising, thinking critically about maternal and neonatal morbidity with prolonged second stage is essential. Existing evidence does support that there is a duration where the risk of
maternal/neonatal morbidity outweigh the chance of a successful vaginal delivery, but that exact time has not been established. A secondary analysis of a multicenter randomized study of 4,126 nulliparous women showed the length of the second stage was not associated with 5-minute APGAR scores of <4, umbilical artery pH <7.0, neonatal intubation, admission to neonatal intensive care unit, or neonatal sepsis but did have increased maternal morbidity (i.e. puerperal infection, higher degree laceration and postpartum hemorrhage)47. Le Ray et. al performed a retrospective study of 1,862 nulliparous women and showed that relative to the first hour, the chance of a spontaneous vaginal delivery of a newborn without signs of asphyxia decreased significantly every hour (1 to 2 hour odds ratio OR 0.4, (95% CI, 0.3-0.6); 2 to 3 hour OR 0.1, (95% CI, 0.09-0.2); and >3 hour OR 0.03, (95% CI, 0.02-0.05))27. Furthermore, in a population-based cohort of 121,517 women by Allen at. al, there was an increased risk of maternal obstetric trauma, postpartum hemorrhage, puerperal febrile morbidity as well as low 5-minute Apgar score, birth depression, and admission to neonatal intensive care unit with prolonged second stage of labor35. Finally, Laughon et. al performed a retrospective cohort of 43,810 nulliparous and 59,605 multiparous women comparing prolonged second stage to those women with labor curves within the guidelines and found significant maternal morbidity (e.g. chorioamnionitis, 3rd and 4th degree laceration) and neonatal morbidity (sepsis, asphyxia, and perinatal mortality)48. Additionally, a retrospective of 5,158 multiparous women with a second stage of 3 hours or more had increased risk of operative delivery, peripartum morbidity, and undesirable neonatal outcomes34. After > 3 hour second stage of labor duration, only 1 in 4 nulliparous
women47 and 1 in 3 multiparous women will give birth spontaneously while 30-50% will require operative delivery to give birth vaginally once these threshold are reached 34. Collectively, longer time in the second stage is associated with increased risk of both maternal and neonatal morbidity, decreasing probability of spontaneous vaginal delivery and should be closely monitored and assessed. Figure 1 presents a proposed algorithm for clinicians to use when assessing the second stage of labor and weighing the maternal and neonatal risk associated with operative delivery and prolonged second stage of labor. Clinicians must use this information critically to manage the second stage of labor. Further research is also needed to help define other fetal or labor characteristics that may aid clinicians in deciding that the second stage of labor has gone on for too long. Key evidence-based management of the second stage of labor In summary, the literature supports several evidence-based management strategies for the second stage of labor that obstetricians may utilize (Table 1). Evidence-based management of the second stage of labor should include, immediate pushing at the start of the second stage, expected delivery within 2 hours for multiparous and 3 hours for nulliparous women in the second stage with no clear defined maximum time but established neonatal and maternal morbidities with longer duration, utilization of operative vaginal delivery and manual rotation alongside ultrasound in trained clinicians when clinically appropriate to minimize maternal and neonatal morbidity, use of warm compress and perineal massage to decrease risk for third- and fourth-degree tears, use of a continuous support person outside of regular nursing care, freedom for women to choose pushing technique and position if progress
is being made and fetal monitoring is not impeded, and finally, use of internal fetal monitoring if clinicians are unable to safely monitor the fetus. At the core of second stage management, clinicians must be assessing for both progression and descent and reassuring fetal status in an on-going manner (Figure 1). Furthermore, if the second stage of labor is not progressing, clinicians may need to individualize their management techniques to each women (e.g. trial of turning down an epidural in a women who is unable to feel where she should push) while considering the risks and benefits of continuation in the second stage, operative vaginal delivery, and cesarean delivery. DISCLOSURE STATEMENT The authors have no financial disclosures.
TABLE AND FIGURES Table 1: Summary of key evidence-based management of second stage of labor Management Recommendation Specific length of time spent in second stage of labor which all women should undergo operative delivery has not been established Immediate pushing should begin following the start of the second stage to decrease maternal and neonatal morbidity Before diagnosing arrest of labor in second stage, if maternal and fetal conditions permit, all for following: -2 hours pushing in multiparous -3 hours of pushing in nulliparous women Longer durations may be appropriate on individualized basis (e.g. epidural analgesia, fetal malposition) as long as progress is occurring Operative vaginal delivery in second stage of labor by experienced and well-trained physician should be considered safe, acceptable alternative to cesarean delivery. Training in, ongoing maintenance of the practical skills related to operative vaginal delivery should be encouraged Manual rotation of fetal occiput in setting of fetal malposition is reasonable interventions to consider before moving to operative delivery. Ultrasound should be used in conjunction to increase success rates. To safely prevent cesarean deliveries in setting of malposition, it is important to assess fetal position in second stage of labor, particularly in setting of abnormal fetal decent Warm compress and perineal massage may be used to decrease the risk of third-degree and fourth-degree lacerations; however, it has no effect on increasing the rate of an intact perineum at delivery Women may assume any birthing position and use any pushing technique they request as long as progress is being made in the second stage of labor Continuous support person in addition to regular nursing care
Clinicians should consider a fetal scalp electrode or internal monitoring if they are unable to reliably monitor the fetus during the second stage of labor
Grade of recommendation 1C Strong recommendation, lowquality evidence 1B Strong recommendation, moderate-quality evidence 1B Strong recommendation, moderate-quality evidence
1B Strong recommendation, moderate-quality evidence
1B Strong recommendation, moderate-quality evidence
1B Strong recommendation, moderate-quality evidence 1C Strong recommendation, lowquality evidence 1C Strong recommendation, lowquality evidence 2C Weak recommendation, low quality evidence
Use of pelvimetry to assess progression in the second stage
2C Weak recommendation, lo quality evidence
Table 2: Maternal and neonatal morbidities by operative delivery
Outcome Maternal Morbidity3 Short-term risks
Long-term risk
Operative Delivery Vaginal operative delivery
Increased risk of third- or fourth-degree tears, highest with forceps-assisted Increases risk of anal incontinence at 6 weeks No difference in bowel/urinary dysfunction at 5 years postpartum compared to vaginal delivery
Neonatal Morbidity33,37 Brachial plexus 0.17-0.43% vacuum injury 0.25-0.56% forceps Facial injury
0.05% vacuum
Cesarean delivery
Hemorrhage Infection Prolonged healing Venous thrombosis
Increased risk for repeat cesarean delivery Increased risk of placental abnormalities Increased health care costs 0.01-0.04%
0.03-0.05%
0.45% forceps
Mechanical ventilation Shoulder dystocia Intracranial hemorrhage Neurologic complications Combined neurologic
Forceps associated with an increased relative risk 5.10, (95% CI, 1.12-23.25) 0.39% vacuum
0.71-1.03%
0.45% forceps 1-2%4
0%
1:664-860
N/A
1:220-385
N/A
0.45% vacuum
0.44%
(seizure, IVH, subdural hemorrhage)
5-minute Apgar score <7 Death
0.26% forceps Forceps-assisted vaginal delivery reduced risk odds ratio 0.60, (95% CI, 0.40-0.90) compared to vacuum-assisted or cesarean delivery 0.76% vacuum 0.98% 0.43% forceps 0.3:1000 vacuum
0.8:1000
0.5:1000 forceps
Table 3. Summarization of maternal and neonatal morbidity associated with prolonged second stage of labor Summary: Increasing maternal and neonatal morbidity, regardless of parity, with prolonged second stage of labor Study, type Maternal Outcomes Neonatal Outcomes and sample size Rouse et. al47 Decreasing rate of spontaneous Increased odds of admission to NICU OR (FOX trial) vaginal delivery as duration 1.4 Retrospective increased (85% <1 hour vs 9% > 5 Increased odds of brachial plexus injury analysis, hours) OR 1.78 (95% CI, 1.08-2.78) 4126 women Increasing rate of chorioamnionitis who reached 3.9% second stage Increasing rate of third- or fourthof labor degree lacerations 8.7% Increasing rate of uterine atony 3.9% Le Ray et. al Compared to 1 hour, increased risk Compared to first hour, chance of a 27 (PEOPLE spontaneous vaginal delivery of infant of postpartum hemorrhage trial) 2-3 hours aOR 1.6 (95% CI, 1.0-2.5) without signs of asphyxia decreased every Secondary > 3 hours aOR 2.5 (95% CI, 1.5-4.1) hour analysis of 1-2 hour aOR 0.4 (95% CI, 0.3-0.6) Intrapartum fever randomized 2-3 hour aOR 0.1 (95% CI, 0.09-0.2) <1 hour 3.3% control trial, >3 hour aOR 0.03 (95% CI, 0.02-0.05) 1-2 hr 6.3%
1,862 women Allen et. al35 Populationbased cohort, 121,517 women
2-3 h 8.8% >3 hours 12.3% 30-fold increased risk of operative delivery if pushing >3 hours Increased risk maternal obstetric trauma 2-3 hours aRR 1.45 (95% CI, 1.321.60) 3-4 hours aRR 1.84 (95% CI, 1.652.06) 4-5 hours aRR 2.07 (95% CI, 1.822.36) >5 hours aRR 2.18 (95% CI, 1.902.50) for nulliparous women and 1-2 hours aRR 1.30 (95% CI, 1.051.62) 2-3 hours aRR 2.01 (95% CI, 1.512.68) >3 hours aRR 1.96 (95% CI, 1.452.67) for multiparous women Postpartum hemorrhage 2-3 hours aRR 1.30 (95% CI, 1.191.43) 3-4 hours aRR 1.53 (95% CI, 1.371.72), 4-5 hours aRR 1.59 (95% CI, 1.391.82), and >5 hours aRR 1.75 (95% CI, 1.522.02) for nulliparous women and 1-2 hours aRR 1.18 (95% CI, 1.021.35), 2-3 hours aRR 1.07 (95% CI, 0.831.37), and >3 hours aRR 1.37 (95% CI, 1.061.77) for multiparous women Puerperal febrile morbidity 2-3 hours aRR 1.30 (95% CI, 1.131.50), 3-4 hours aRR 1.63 (95% CI, 1.391.92), 4-5 hours aRR 1.51 (95% CI, 1.251.83), >5 hours aRR 1.49 (95% CI, 1.21-
Low 5-minute Apgar score 2-3 hours aRR 1.33 (95% CI, 1.07-1.64), 3-4 hours aRR 1.36 (95% CI, 1.04-1.77) for neonates of nulliparous women and 1-2 hours aRR 1.75 (95% CI, 1.23-2.51), 2-3 hours aRR 2.64 (95% CI, 1.59-4.37), and >3 hours aRR 2.24 (95% CI, 1.25-4.0) for neonates of multiparous women Birth depression 2-3 hours aRR 1.68 (95% CI, 1.43-1.98), 3-4 hours aRR 1.59 (95% CI, 1.29-1.97), 4-5 hours aRR 1.93 (95% CI, 1.51-2.47), and >5 hours aRR 1.96 (95% CI, 1.51-2.55) for neonates of nulliparous women and 1-2 hours aRR 1.27 (95% CI, 0.95-1.70), 2-3 hours aRR 1.76 (95% CI, 1.15-2.71), and >3 hours aRR 1.68 (95% CI, 1.05-2.70) for neonates born to multiparous women Admission to neonatal intensive care unit 2-3 hours aRR 1.43 (95% CI, 1.30-1.57), 3-4 hours aRR 1.94 (95% CI, 1.74-2.16), 4-5 hours aRR 2.10 (95% CI, 1.84-2.40), and >5 hours aRR 1.99 (95% CI, 1.72-2.30) for neonates born to nulliparous women and 1-2 hours aRR 1.35 (95% CI, 1.17-1.56), 2-3 hours aRR 1.50 (95% CI, 1.19-1.90) and >3 hours aRR 1.55 (95% CI, 1.20-2.0) for neonates born to multiparous women Composite perinatal morbidity 2-3 hours 1.52 (95% CI, 1.41-1.64), 3-4 hours 1.74 (95% CI, 1.59-1.91), 4-5 hours 1.94 (95% CI, 1.74-2.17), and >5 hours 1.85 (95% CI, 1.64-2.08) for neonates born to nulliparous women and
Laughon et. 48 al Retrospective cohort, 43,810 nuliparous & 59,605 multiparous singleton deliveries
1.84) for nulliparous women and 1-2 hours aRR 1.78 (95% CI, 1.382.29), 2-3 hours aRR 1.73 (95% CI, 1.152.58) and >3 hours aRR 3.17 (95% CI, 2.194.58) for multiparous women Composite maternal morbidity 2-3 hours aRR 1.82 (95% CI, 1.721.94), 3-4 hours aRR2.51 (95% CI, 2.332.70), 4-5 hours aRR 2.94 (95% CI, 2.693.22), and >5 hours RR 3.29 (95% CI, 2.99-3.61) for nulliparous women and 1-2 hours aRR 1.28 (95% CI, 1.141.43), 2-3 hours aRR 1.46 (95% CI, 1.221.75), and >3 hours aRR 1.73 (95% CI, 1.442.10) for multiparous women Composite maternal morbidity higher nulliparous women with an epidural with prolonged second stage aOR 1.42 (95% CI, 1.25-1.62) Increased rates of chorioamnionitis aOR 3.01 (95% CI, 2.65-3.43) nullips with epidural & aOR 3.18 (95% CI, 2.34-4.33) nullips without epidural aOR 4.78 (95% CI, 3.46-6.61) & aOR 2.34 (95% CI, 1.16-4.72) for multips with and without epidural Endometritis nullips with epidural aOR 3.21 (95% CI, 2.25-4.57) Wound separation nullips with epidural aOR 12.13 (95% CI, 3.6340.46) Postpartum hemorrhage nullips with epidural aOR 1.50 (95% CI, 1.27-1.78) Increased rates of third- or fourthdegree lacerations
1-2 hours 1.38 (95% CI, 1.23-1.56), 2-3 hours 1.64 (95% CI, 1.35-1.98), and >3 hours 1.42 (95% CI, 1.14-1.76) for women born to multiparous women
Sepsis nulliparous women with epidural aOR 2.08 (95% CI, 1.60-2.70) and without epidural aOR 2.34 (95% CI, 1.28-4.27) Asphyxia nulliparous with epidural aOR 2.39 (95% CI, 1.22-4.66) Perinatal mortality nulliparous women without epidural aOR 5.92 (95% CI, 1.4324.51) and aOR 6.34 (95% CI, 1.32-30.34) multiparous women
aOR 1.80 (95% CI, 1.58-2.05) nullips with epidural and aOR 1.78 (95% CI, 1.43-2.22) nullips without epidural, aOR 3.85 (95% CI, 2.65-5.60) & aOR 3.20 (95% CI, 1.71-5.99) multips with and without epidural
Figure 1: Second stage management algorithm
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