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Cesarean delivery outcomes after a prolonged second stage of labor
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Cesarean delivery outcomes after a prolonged second stage of labor Joyce F. Sung, MD; Kay I. Daniels, MD; Laura Brodzinsky, MD; Yasser Y. El-Sayed, MD; Aaron B. Caughey, MD, PhD; Deirdre J. Lyell, MD OBJECTIVE: We hypothesized that prolonged second stage of labor increases the incidence of unintentional hysterotomy extensions at cesarean delivery. STUDY DESIGN: A retrospective cohort of term pregnant women who underwent primary cesarean delivery after failed second stage of labor at Stanford University was assessed for hysterotomy extensions and other maternal and neonatal morbidities. Groups included second stage length of 1-3 hours and ⬎4 hours. Data were analyzed with the use of chi-square and Fisher’s exact tests.
hysterotomy extensions (40% vs 26%; P ⫽ .03), particularly to the cervix (29% vs 5%; P ⫽ .005), and with surgery that lasted ⬎90 minutes (9% vs 1%; P ⫽ .01). The incidence of hysterotomy extensions was associated positively with the length of the second stage. Other maternal and neonatal morbidities were similar between groups. CONCLUSION: Prolonged second stage of labor is associated with an increase in unintentional hysterotomy extensions at cesarean delivery and prolonged operative time. The future risk of hysterotomy extensions merits further investigation.
RESULTS: Of the 239 women who were studied, the second stage of
labor lasted 1-3 hours in 82 patients and ⬎4 hours in 157 patients. Prolonged second stage of labor was associated with unintentional
Key words: cesarean delivery, hysterotomy extension, maternal morbidity, prolonged second stage of labor
Cite this article as: Sung JF, Daniels KI, Brodzinsky L, El-Sayed YY, Caughey AB, Lyell DJ. Cesarean delivery outcomes after a prolonged second stage of labor. Am J Obstet Gynecol 2007;197:306.e1-306.e5.
T
he second stage of labor historically was limited to ⬍2 hours, based on the observations that most nulliparous patients delivered within this time period1 and that neonatal mortality rates increased when the second stage was prolonged.2 With the advent of noninvasive fetal monitoring, obstetricians allowed the second stage to last ⬎2 hours.3 As regional anesthesia became increasingly common, the limit of second stage was extended further; most nulliparous patients with regional anesthesia were found to deliver within 3 hours of second
From the Department of Obstetrics and Gynecology, Stanford University, Stanford, CA (Drs Sung, Daniels, Brodzinsky, ElSayed, and Lyell), and the Department of Obstetrics, Gynecology and Reproductive Sciences, University of California–San Francisco, San Francisco, CA (Dr Caughey). Presented at the 27th Annual Clinical Meeting of the Society for Maternal-Fetal Medicine, San Francisco, CA, Feb. 5-10, 2007. Reprints not available from the authors. 0002-9378/$32.00 © 2007 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2007.07.005
306.e1
stage vs 2 hours in those patients without regional anesthesia.4 Indeed, allowing additional time in second stage ⬎2 hours results in an increased overall vaginal delivery rate.5 A second stage lasting up to 3 hours is considered appropriate,4,6 and second stages that last ⬎4 hours are not uncommon.7-10 Although a prolonged second stage of labor does not appear to increase neonatal morbidities,6,7,11 maternal morbidities are increased and include operative vaginal delivery, anal sphincter tear, cesarean delivery, and postpartum hemorrhage.6,7,11 When compared with cesarean deliveries in the first stage of labor, cesarean deliveries in the second stage have been associated with longer surgery time,12 increased postoperative fevers,12 maternal intraoperative trauma,13 and composite maternal morbidity.14 Although 1 small study showed increased neonatal morbidity,12 larger studies have shown no differences in neonatal morbidity.13,14 We hypothesized that prolonged second stage of labor that results in cesarean delivery is associated with more frequent unintentional hysterotomy extensions, when compared with a shorter second
American Journal of Obstetrics & Gynecology SEPTEMBER 2007
stage. Further, we sought to identify whether cesarean delivery after prolonged second stage of labor is associated with increased composite maternal and neonatal morbidity and to identify any factors that may help predict increased morbidity.
M ATERIALS AND M ETHODS We analyzed a retrospective cohort of patients who underwent primary cesarean delivery during the second stage of labor at Lucile Packard Children’s Hospital at Stanford University between 2001 and 2004. This is a tertiary care academic center that includes both a private service and a faculty practice with resident involvement. All resident deliveries were supervised by a faculty physician. At our institution, the routine practice for cesarean delivery after a prolonged second stage of labor does not differ substantially from cesarean deliveries for other indications. After prolonged second stage of labor, surgeons often elevate the infant’s head vaginally before cesarean delivery. In all cesarean deliveries, patients receive antibiotic prophylaxis after cord clamp and com-
SMFM Papers
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TABLE 1
Maternal and neonatal demographics
Demographic Age (y)*
Cesarean delivery after second stage that lasted 1-3 hours (n ⴝ 82) 32.3 ⫾ 5.2
Cesarean delivery after second stage that lasted >4 hours (n ⴝ 157)
P value
30.9 ⫾ 5.7
.07
................................................................................................................................................................................................................................................................................................................................................................................
Race (n)
.34
.......................................................................................................................................................................................................................................................................................................................................................................
White (45%)
32 (40%)
76 (48%)
Hispanic (23%)
21 (26%)
34 (22%)
Asian (24%)
20 (25%)
37 (23%)
....................................................................................................................................................................................................................................................................................................................................................................... ....................................................................................................................................................................................................................................................................................................................................................................... .......................................................................................................................................................................................................................................................................................................................................................................
African American (2.5%)
4 (5%)
2 (1%)
Pacific Islander (1.3%)
0
3 (2%)
Other (4.2%)
4 (5%)
6 (4%)
Public insurance: 25% (n)
20 (24%)
40 (25%)
Nulliparity (n)
61 (75%)
141 (89%)
Gestational age (wk)*
39.8 ⫾ 1.1
39.6 ⫾ 1.2
⬍40 (n)
32 (39%)
70 (44%)
ⱖ40 (n)
50 (61%)
88 (56%)
38 (46%)
69 (44%)
....................................................................................................................................................................................................................................................................................................................................................................... ....................................................................................................................................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................................................................................................................................................
1.00
................................................................................................................................................................................................................................................................................................................................................................................
.005
................................................................................................................................................................................................................................................................................................................................................................................
.21
....................................................................................................................................................................................................................................................................................................................................................................... .......................................................................................................................................................................................................................................................................................................................................................................
................................................................................................................................................................................................................................................................................................................................................................................
Induction of labor (n)
.78
................................................................................................................................................................................................................................................................................................................................................................................
Indication for induction of labor (n)
.07
.......................................................................................................................................................................................................................................................................................................................................................................
Diabetes mellitus
0
9 (13%)
Oligohydramnios
2 (5%)
5 (7%)
....................................................................................................................................................................................................................................................................................................................................................................... .......................................................................................................................................................................................................................................................................................................................................................................
Preeclampsia
3 (8%)
5 (7%)
Postdue date
20 (51%)
29 (41%)
Premature rupture of membranes
5 (13%)
15 (21%)
Other
9
....................................................................................................................................................................................................................................................................................................................................................................... ....................................................................................................................................................................................................................................................................................................................................................................... .......................................................................................................................................................................................................................................................................................................................................................................
8
................................................................................................................................................................................................................................................................................................................................................................................
Diabetes mellitus
4 (5%)
17 (11%)
.15
General anesthesia during cesarean delivery
1 (1%)
6 (4%)
.43
Epidural during labor
79 (96%)
154 (97%)
.69
Operative vaginal delivery attempt
17 (21%)
33 (21%)
1.00
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
Birthweight (g)*
3601 ⫾ 446
3676 ⫾ 446
.22
................................................................................................................................................................................................................................................................................................................................................................................
⬎4000 (n)
15 (18%)
45 (28%)
.12
................................................................................................................................................................................................................................................................................................................................................................................
* Data are presented as mean ⫾ SD.
pression stockings for deep venous thrombosis prophylaxis. Inclusion criteria were patients with a full-term singleton pregnancy who underwent primary cesarean delivery during the second stage of labor. Second stage of labor was defined as the time from complete dilation until delivery. Cases were patients with a second stage of ⬎4 hours (⬎240 minutes), which we refer to as “prolonged second stage”; and control subjects were patients with a second stage of labor that lasted 1-3 hours
(60-180 minutes). We chose a second stage that lasted 1-3 hours for the control group to further dichotomize any potential differences in outcomes that were based on duration of the second stage. Exclusion criteria were multiple gestation, previous myomectomy, type I diabetes mellitus, steroid-dependent disease, anticoagulation, and body mass index ⱖ40 kg/m2. All cases and control subjects were identified with the use of the Lucile Packard Children’s Hospital Perinatal Database.
The primary outcome was unintentional hysterotomy extension at cesarean delivery. This was assessed by review of the surgeon’s dictated operative notes that identified any description of an unintentional hysterotomy extension. The location and number of extensions were noted. We assumed a 22.5% incidence of hysterotomy extension when the second stage lasted 1-3 hours and a 45% incidence with a ⬎4-hour second stage of labor. To have 80% power to detect a 50% difference in hysterotomy exten-
SEPTEMBER 2007 American Journal of Obstetrics & Gynecology
306.e2
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TABLE 2
Maternal outcomes
Outcome
Cesarean delivery after second stage that lasted 1-3 hours (n ⴝ 82)
Cesarean delivery after second stage that lasted >4 hours (n ⴝ 157)
P value
Hysterotomy extension (n)
21 (26%)
63 (40%)
.03
Chorioamnionitis (n)
20 (24%)
53 (33.5%)
.18
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
Disseminated intravascular coagulation (n)
2 (2.5%)
2 (1%)
.61
Uterine atony (n)
9 (11%)
12 (8%)
.47
Length of stay ⬎4 d (n)
4 (5%)
13 (8%)
.43
14 (17%)
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
Postoperative fever (n)
30 (19%)
.73
Intensive care unit admission (n)
1 (1%)
4 (2.5%)
.66
Repeat surgery (n)
1 (1%)
0
.34
Blood transfusion (n)
3 (4%)
9 (6%)
.76
843 ⫾ 340
882 ⫾ 293
.35
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
Estimated blood loss (mL)*
................................................................................................................................................................................................................................................................................................................................................................................
7.3 ⫾ 4.0
Hematocrit drop* (%)
7.0 ⫾ 3.9
.57
................................................................................................................................................................................................................................................................................................................................................................................
Hematocrit drop ⱖ 10% (n)
23 (28%)
40 (25%)
.64
7 (8.5%)
21 (13%)
.30
................................................................................................................................................................................................................................................................................................................................................................................ †
Postoperative complications (n)
................................................................................................................................................................................................................................................................................................................................................................................
44.7 ⫾ 12.5
Operative time (min)*
51.0 ⫾ 20.7
.01
1 (1%)
15 (9%)
.01
11 (13%)
30 (19%)
.37
................................................................................................................................................................................................................................................................................................................................................................................
Operative time ⱖ90 min (n)
................................................................................................................................................................................................................................................................................................................................................................................ ‡
Composite maternal morbidity (n)
................................................................................................................................................................................................................................................................................................................................................................................
* Data are presented as mean ⫾ SD. †
Includes wound complications, ileus, anemia, disseminated intravascular coagulation, deep venous thrombosis, and pulmonary embolism.
‡
Includes cystotomy, disseminated intravascular coagulation, transfusion, intensive care unit admission, repeat surgery, postoperative complications, and length of stay of ⬎4 days.
sions, with an alpha of .05 and a beta of .2, 74 patients per arm were needed. Secondary outcomes were composite and individual maternal morbidities, included chorioamnionitis, disseminated intravascular coagulation, uterine atony, length of stay of ⬎4 days, postoperative fever (temperature, ⬎38°C), intensive care unit admission, repeat surgery, blood transfusion, blood loss, postoperative complications (including wound seroma, ileus, anemia, disseminated intravascular coagulation, deep venous thrombosis, pulmonary embolism), and length of surgery. Neonatal outcomes included 5-minute Apgar score of ⬍7, presence of meconium, arterial cord pH ⬍7.2, neonatal intensive care unit (NICU) admission, and NICU length of stay. All patients underwent continuous electronic fetal monitoring throughout labor. Data were entered into a STATA database (Statacorp, College Station, TX). Univariate statistical tests with the chi306.e3
square test of proportions and the Fisher’s exact test were considered statistically significant if the probability value was ⬍.05. Multivariable logistic regression analysis was used to control for potential confounding variables. We received approval for this study from the Committee on Human Research at Stanford University Medical Center.
R ESULTS Two hundred forty patients met eligibility criteria; 1 patient was not included because her chart was unavailable for review. Of the 239 patients whose cases were assessed, 82 patients had a second stage of labor that lasted 1-3 hours, and 157 patients had a second stage of labor that lasted ⬎4 hours. Maternal and neonatal demographics were similar between groups (Table 1). All hysterotomies were low transverse. Prolonged second stage of labor was associated with unintentional hysterot-
American Journal of Obstetrics & Gynecology SEPTEMBER 2007
omy extensions (Table 2). The incidence of hysterotomy extensions increased with the length of the second stage (25% at 1-3 hours, 32% at 4-5 hours, and 47% at ⬎5 hours; P ⫽ .01). Prolonged second stage of labor was associated with an increase in the incidence of hysterotomy extensions to the cervix (29% vs 5%; P ⫽ .005; Table 3). By location, hysterotomy extensions occurred most frequently in the lower uterine segment, followed by the cervix, other locations, and the broad ligament (Table 3). The occurrence of ⬎1 hysterotomy extension was not more frequent with a prolonged second stage of labor. Total operative time was longer after a prolonged second stage of labor. Cesarean deliveries more frequently lasted ⬎90 minutes among women with a prolonged second stage of labor (Table 2). There were no differences in the other studied maternal morbidities between groups, nor was there a difference in composite morbidity (Table 2).
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TABLE 3
Location of hysterotomy extensions
Location
Hysterotomy extensions with cesarean delivery after second stage that lasted 1-3 hours (n ⴝ 21)
Hysterotomy extensions with cesarean delivery after second stage that lasted >4 hours (n ⴝ 63)
Lower uterine segment (n)
19 (90%)
38 (64%)
Cervix (n)
1 (5%)
17 (29%)
.005
Broad ligament (n)
0
2 (3%)
.87
Other (n)
1 (5%)
2 (3%)
P value .87
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
A multivariable logistic regression analysis was performed that controlled for potential confounding variables (Table 4). Unintentional hysterotomy extensions were ⬎2 times more frequent with a prolonged second stage of labor and 2 times more frequent when oxytocin was used during labor, independent of the length of the second stage. The other variables that were examined were not associated independently with hysterotomy extensions. Neonatal outcomes were not significantly different between groups (Table 5).
TABLE 4
Hysterotomy extensions and prolonged second stage of labor, multivariable outcomes* Variable
Odds ratio (95% CI)
⬎4-Hour second stage 2.18 (1.13-4.22) of labor
...........................................................................................................
C OMMENT In our study, cesarean delivery after a second stage of labor that lasted ⬎4 hours was associated with unintentional hysterotomy extensions, particularly to the cervix. The risk appears to increase with the duration of the second stage, because we found a positive association between the length of a prolonged second stage of labor and the incidence of extensions. Use of oxytocin during labor also conferred an independent risk of unintentional hysterotomy extensions. Both findings were independent of attempted operative vaginal delivery, obesity, and birthweight. Prolonged labor may increase attenuation of the lower uterine segment and impaction of the fetal head, giving rise to a thin, easily lacerated lower uterine segment and cervix. Oxytocin use may be a proxy for an abnormal labor or may lead to greater attenuation of the lower uterine seg-
1.0
ment. Our findings are in contrast to those of Allen et al,13 who found an association between intraoperative trauma during cesarean delivery in second stage, compared with first stage, but not when prolonged second stage of labor of ⬎4 hours was compared with second stage of ⱕ4 hours. Operative times were increased among patients with a prolonged second stage of labor, likely because of the increased time that was needed to repair hysterotomy extensions. We did not identify an increase in any of the other maternal morbidities that we examined, which included blood loss and bladder injury, but we were not powered to identify small differences. Several recent studies have shown that prolonged second stage of labor does not affect neonatal morbidity, regardless of mode of delivery.6,7,11 We assessed a limited number of neonatal outcomes and
TABLE 5
Neonatal outcomes*
Chorioamnionitis
1.67 (0.89-3.13)
Outcome
Age ⱖ35 y
0.49 (0.24-1.00)
5-Minute Apgar score ⬍7†
Parity
0.93 (0.53-1.64)
...................................................................................................................................................................................................................................... ‡
Operative vaginal delivery attempt
0.71 (0.33-1.53)
...................................................................................................................................................................................................................................... §
Body mass index ⱖ 30 kg/m2
0.78 (0.42-1.44)
Birthweight ⱖ4000 g
0.76 (0.38-1.53)
Public insurance
0.68 (0.27-1.73)
Preeclampsia
1.61 (0.33-7.74)
........................................................................................................... ........................................................................................................... ...........................................................................................................
1-3 Hours
>4 Hours
P value
2 (2)
2 (1)
.61
Meconium
29 (42)
44 (43)
1.00
Arterial cord pH ⬍7.2
20 (50)
26 (35)
.12
Neonatal intensive care unit admission储
27 (34)
58 (37)
.67
......................................................................................................................................................................................................................................
...........................................................................................................
......................................................................................................................................................................................................................................
........................................................................................................... ........................................................................................................... ...........................................................................................................
Neonatal intensive care unit admission length of stay (days)¶ # †
N ⫽ 183.
Pitocin augmentation
N ⫽ 172.
§
N ⫽ 115.
储
N ⫽ 237.
* Variables that were controlled for: chorioamnionitis, age ⱖ 35 y, parity, operative vaginal delivery attempt, body mass index ⱖ30, birthweight ⱖ4000 g, public insurance, preeclampsia, and oxytocin augmentation.
.63
* Data were not available for all patients. ‡
2.01 (1.08-3.75)
3.3 ⫾ 2.1
......................................................................................................................................................................................................................................
........................................................................................................... ...........................................................................................................
2.9 ⫾ 1.4
¶
N ⫽ 82.
#
Data are presented as mean ⫾ SD.
SEPTEMBER 2007 American Journal of Obstetrics & Gynecology
306.e4
SMFM Papers also did not identify an increase in neonatal morbidity with prolonged second stage of labor. Of note, a large number of newborn infants in our study were admitted to the NICU, likely because it is routine practice at our institution to admit all newborn infants with the diagnosis of chorioamnionitis to the NICU for evaluation. Our study was limited by its retrospective nature. The presence and details of unintentional hysterotomy extensions relied on the surgeon’s accurate dictation. Further, because this was not a randomized study, the findings may be biased because of confounding. We attempted to control for potential confounding with multivariable logistic regression; however, residual confounding may exist because of confounders that we did not consider or abstract from the medical records. Our data may be helpful in encouraging obstetricians to modify labor management and cesarean technique and with counseling patients who are considering a prolonged second stage of labor. Greater focus and education on careful technique in delivering the fetal head and shoulders through the uterine incision after a prolonged second stage of labor may be appropriate. It is our clinical experience that, with a cesarean delivery that is performed after a prolonged second stage of labor, care should be taken to place the hysterotomy slightly higher on the lower uterine segment. The significance of unintentional hysterotomy extensions, with regard to future
306.e5
www.AJOG.org uterine rupture and cervical insufficiency, is not clear and needs further study. Intentional superior and inferior hysterotomy extensions are believed anecdotally to increase the risk for uterine rupture. Unintentional hysterotomy extensions theoretically could be associated with increased uterine rupture risk as well. Cervical insufficiency has been associated both with a prolonged second stage of labor of ⬎3 hours in a previous pregnancy15 and with cervical trauma, such as conization.16 Whether cervical hysterotomy extensions at time of cesarean delivery increase the risk of future cervical insufficiency is unknown, but plausible. The increase in hysterotomy extensions may have as yet unknown effects on future pregnancies, including increased uterine rupture risk or risk for cervical insufficiency. Both of these questions deserve further investigation. f REFERENCES 1. Friedman EA. Primigravid labor: a graphicostatistical analysis. Obstet Gynecol 1955;6: 567-89. 2. Hellman LM, Prystowsky H. The duration of the second stage of labor. Am J Obstet Gynecol 1952;63:1223-33. 3. Cohen WR. Influence of the duration of second stage labor on perinatal outcome and puerperal morbidity. Obstet Gynecol 1977;49: 266-9. 4. Kilpatrick SJ, Laros RK. Characteristics of normal labor. Obstet Gynecol 1989;74:85-7. 5. Myles TD, Santolaya J. Maternal and neonatal outcomes in patients with a prolonged second stage of labor. Obstet Gynecol 2003; 102:52-8. 6. Saunders N, Paterson CM, Wadworth J. Neonatal and maternal morbidity in relation to
American Journal of Obstetrics & Gynecology SEPTEMBER 2007
the length of the second stage of labour. BJOG 1992;99:381-5. 7. Cheng YW, Hopkins LM, Caughey AB. How long is too long: does a prolonged second stage of labor in nulliparous women affect maternal and neonatal outcomes? Am J Obstet Gynecol 2004;191:933-8. 8. O’Connell MP, Hussain J, Maclennan FA, Lindow SW. Factors associated with a prolonged second stage of labour: a case-controlled study of 364 nulliparous labours. J Obstet Gynaecol 2003;23:255-7. 9. Menticoglou SM, Manning F, Harman C, Morrison I. Perinatal outcome in relation to second-stage duration. Am J Obstet Gynecol 1995;173:906-12. 10. Paterson CM, Saunders N. The characteristics of the second stage of labour in 25069 singleton deliveries in the North West Thames health region, 1988. BJOG 1992;99:377-80. 11. Janni W, Schiessl B, Peschers U, et al. The prognostic impact of a prolonged second stage of labor on maternal and fetal outcome. Acta Obstet Gynecol Scand 2002;81:214-21. 12. Cebekulu L, Buchman EJ. Complications associated with cesarean section in the second stage of labor. Int J Gynaecol Obstet 2006; 95:110-4. 13. Allen VM, O’Connell CM, Baskett TF. Maternal and perinatal morbidity of caesarean delivery at full cervical dilatation compared with caesarean delivery in the first stage of labour. BJOG 2005;112:986-90. 14. Alexander JM, Leveno, KJ, Rouse DJ, et al. Comparison of maternal and infant outcomes from primary cesarean delivery during the second compared with first stage of labor. Obstet Gynecol 2007;109:917-21. 15. Vyas NA, Vink JS, Ghidini A, et al. Risk factors for cervical insufficiency after term delivery. Am J Obstet Gynecol 2006;195:787-91. 16. Moinian M, Andersch R. Does cervix conization increase the risk of complications in subsequent pregnancies? Acta Obstet Gynecol Scand 1982;61:101-3.
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Cesarean delivery outcomes after a prolonged second stage of labor Joyce F. Sung, MD; Kay I. Daniels, MD; Laura Brodzinsky, MD; Yasser Y. El-Sayed, MD; Aaron B. Caughey, MD, PhD; Deirdre J. Lyell, MD OBJECTIVE: We hypothesized that prolonged second stage of labor increases the incidence of unintentional hysterotomy extensions at cesarean delivery. STUDY DESIGN: A retrospective cohort of term pregnant women who underwent primary cesarean delivery after failed second stage of labor at Stanford University was assessed for hysterotomy extensions and other maternal and neonatal morbidities. Groups included second stage length of 1-3 hours and ⬎4 hours. Data were analyzed with the use of chi-square and Fisher’s exact tests.
hysterotomy extensions (40% vs 26%; P ⫽ .03), particularly to the cervix (29% vs 5%; P ⫽ .005), and with surgery that lasted ⬎90 minutes (9% vs 1%; P ⫽ .01). The incidence of hysterotomy extensions was associated positively with the length of the second stage. Other maternal and neonatal morbidities were similar between groups. CONCLUSION: Prolonged second stage of labor is associated with an increase in unintentional hysterotomy extensions at cesarean delivery and prolonged operative time. The future risk of hysterotomy extensions merits further investigation.
RESULTS: Of the 239 women who were studied, the second stage of
labor lasted 1-3 hours in 82 patients and ⬎4 hours in 157 patients. Prolonged second stage of labor was associated with unintentional
Key words: cesarean delivery, hysterotomy extension, maternal morbidity, prolonged second stage of labor
Cite this article as: Sung JF, Daniels KI, Brodzinsky L, El-Sayed YY, Caughey AB, Lyell DJ. Cesarean delivery outcomes after a prolonged second stage of labor. Am J Obstet Gynecol 2007;197:306.e1-306.e5.
T
he second stage of labor historically was limited to ⬍2 hours, based on the observations that most nulliparous patients delivered within this time period1 and that neonatal mortality rates increased when the second stage was prolonged.2 With the advent of noninvasive fetal monitoring, obstetricians allowed the second stage to last ⬎2 hours.3 As regional anesthesia became increasingly common, the limit of second stage was extended further; most nulliparous patients with regional anesthesia were found to deliver within 3 hours of second
From the Department of Obstetrics and Gynecology, Stanford University, Stanford, CA (Drs Sung, Daniels, Brodzinsky, ElSayed, and Lyell), and the Department of Obstetrics, Gynecology and Reproductive Sciences, University of California–San Francisco, San Francisco, CA (Dr Caughey). Presented at the 27th Annual Clinical Meeting of the Society for Maternal-Fetal Medicine, San Francisco, CA, Feb. 5-10, 2007. Reprints not available from the authors. 0002-9378/$32.00 © 2007 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2007.07.005
306.e1
stage vs 2 hours in those patients without regional anesthesia.4 Indeed, allowing additional time in second stage ⬎2 hours results in an increased overall vaginal delivery rate.5 A second stage lasting up to 3 hours is considered appropriate,4,6 and second stages that last ⬎4 hours are not uncommon.7-10 Although a prolonged second stage of labor does not appear to increase neonatal morbidities,6,7,11 maternal morbidities are increased and include operative vaginal delivery, anal sphincter tear, cesarean delivery, and postpartum hemorrhage.6,7,11 When compared with cesarean deliveries in the first stage of labor, cesarean deliveries in the second stage have been associated with longer surgery time,12 increased postoperative fevers,12 maternal intraoperative trauma,13 and composite maternal morbidity.14 Although 1 small study showed increased neonatal morbidity,12 larger studies have shown no differences in neonatal morbidity.13,14 We hypothesized that prolonged second stage of labor that results in cesarean delivery is associated with more frequent unintentional hysterotomy extensions, when compared with a shorter second
American Journal of Obstetrics & Gynecology SEPTEMBER 2007
stage. Further, we sought to identify whether cesarean delivery after prolonged second stage of labor is associated with increased composite maternal and neonatal morbidity and to identify any factors that may help predict increased morbidity.
M ATERIALS AND M ETHODS We analyzed a retrospective cohort of patients who underwent primary cesarean delivery during the second stage of labor at Lucile Packard Children’s Hospital at Stanford University between 2001 and 2004. This is a tertiary care academic center that includes both a private service and a faculty practice with resident involvement. All resident deliveries were supervised by a faculty physician. At our institution, the routine practice for cesarean delivery after a prolonged second stage of labor does not differ substantially from cesarean deliveries for other indications. After prolonged second stage of labor, surgeons often elevate the infant’s head vaginally before cesarean delivery. In all cesarean deliveries, patients receive antibiotic prophylaxis after cord clamp and com-
SMFM Papers
www.AJOG.org
TABLE 1
Maternal and neonatal demographics
Demographic Age (y)*
Cesarean delivery after second stage that lasted 1-3 hours (n ⴝ 82) 32.3 ⫾ 5.2
Cesarean delivery after second stage that lasted >4 hours (n ⴝ 157)
P value
30.9 ⫾ 5.7
.07
................................................................................................................................................................................................................................................................................................................................................................................
Race (n)
.34
.......................................................................................................................................................................................................................................................................................................................................................................
White (45%)
32 (40%)
76 (48%)
Hispanic (23%)
21 (26%)
34 (22%)
Asian (24%)
20 (25%)
37 (23%)
....................................................................................................................................................................................................................................................................................................................................................................... ....................................................................................................................................................................................................................................................................................................................................................................... .......................................................................................................................................................................................................................................................................................................................................................................
African American (2.5%)
4 (5%)
2 (1%)
Pacific Islander (1.3%)
0
3 (2%)
Other (4.2%)
4 (5%)
6 (4%)
Public insurance: 25% (n)
20 (24%)
40 (25%)
Nulliparity (n)
61 (75%)
141 (89%)
Gestational age (wk)*
39.8 ⫾ 1.1
39.6 ⫾ 1.2
⬍40 (n)
32 (39%)
70 (44%)
ⱖ40 (n)
50 (61%)
88 (56%)
38 (46%)
69 (44%)
....................................................................................................................................................................................................................................................................................................................................................................... ....................................................................................................................................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................................................................................................................................................
1.00
................................................................................................................................................................................................................................................................................................................................................................................
.005
................................................................................................................................................................................................................................................................................................................................................................................
.21
....................................................................................................................................................................................................................................................................................................................................................................... .......................................................................................................................................................................................................................................................................................................................................................................
................................................................................................................................................................................................................................................................................................................................................................................
Induction of labor (n)
.78
................................................................................................................................................................................................................................................................................................................................................................................
Indication for induction of labor (n)
.07
.......................................................................................................................................................................................................................................................................................................................................................................
Diabetes mellitus
0
9 (13%)
Oligohydramnios
2 (5%)
5 (7%)
....................................................................................................................................................................................................................................................................................................................................................................... .......................................................................................................................................................................................................................................................................................................................................................................
Preeclampsia
3 (8%)
5 (7%)
Postdue date
20 (51%)
29 (41%)
Premature rupture of membranes
5 (13%)
15 (21%)
Other
9
....................................................................................................................................................................................................................................................................................................................................................................... ....................................................................................................................................................................................................................................................................................................................................................................... .......................................................................................................................................................................................................................................................................................................................................................................
8
................................................................................................................................................................................................................................................................................................................................................................................
Diabetes mellitus
4 (5%)
17 (11%)
.15
General anesthesia during cesarean delivery
1 (1%)
6 (4%)
.43
Epidural during labor
79 (96%)
154 (97%)
.69
Operative vaginal delivery attempt
17 (21%)
33 (21%)
1.00
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
Birthweight (g)*
3601 ⫾ 446
3676 ⫾ 446
.22
................................................................................................................................................................................................................................................................................................................................................................................
⬎4000 (n)
15 (18%)
45 (28%)
.12
................................................................................................................................................................................................................................................................................................................................................................................
* Data are presented as mean ⫾ SD.
pression stockings for deep venous thrombosis prophylaxis. Inclusion criteria were patients with a full-term singleton pregnancy who underwent primary cesarean delivery during the second stage of labor. Second stage of labor was defined as the time from complete dilation until delivery. Cases were patients with a second stage of ⬎4 hours (⬎240 minutes), which we refer to as “prolonged second stage”; and control subjects were patients with a second stage of labor that lasted 1-3 hours
(60-180 minutes). We chose a second stage that lasted 1-3 hours for the control group to further dichotomize any potential differences in outcomes that were based on duration of the second stage. Exclusion criteria were multiple gestation, previous myomectomy, type I diabetes mellitus, steroid-dependent disease, anticoagulation, and body mass index ⱖ40 kg/m2. All cases and control subjects were identified with the use of the Lucile Packard Children’s Hospital Perinatal Database.
The primary outcome was unintentional hysterotomy extension at cesarean delivery. This was assessed by review of the surgeon’s dictated operative notes that identified any description of an unintentional hysterotomy extension. The location and number of extensions were noted. We assumed a 22.5% incidence of hysterotomy extension when the second stage lasted 1-3 hours and a 45% incidence with a ⬎4-hour second stage of labor. To have 80% power to detect a 50% difference in hysterotomy exten-
SEPTEMBER 2007 American Journal of Obstetrics & Gynecology
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TABLE 2
Maternal outcomes
Outcome
Cesarean delivery after second stage that lasted 1-3 hours (n ⴝ 82)
Cesarean delivery after second stage that lasted >4 hours (n ⴝ 157)
P value
Hysterotomy extension (n)
21 (26%)
63 (40%)
.03
Chorioamnionitis (n)
20 (24%)
53 (33.5%)
.18
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
Disseminated intravascular coagulation (n)
2 (2.5%)
2 (1%)
.61
Uterine atony (n)
9 (11%)
12 (8%)
.47
Length of stay ⬎4 d (n)
4 (5%)
13 (8%)
.43
14 (17%)
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
Postoperative fever (n)
30 (19%)
.73
Intensive care unit admission (n)
1 (1%)
4 (2.5%)
.66
Repeat surgery (n)
1 (1%)
0
.34
Blood transfusion (n)
3 (4%)
9 (6%)
.76
843 ⫾ 340
882 ⫾ 293
.35
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
Estimated blood loss (mL)*
................................................................................................................................................................................................................................................................................................................................................................................
7.3 ⫾ 4.0
Hematocrit drop* (%)
7.0 ⫾ 3.9
.57
................................................................................................................................................................................................................................................................................................................................................................................
Hematocrit drop ⱖ 10% (n)
23 (28%)
40 (25%)
.64
7 (8.5%)
21 (13%)
.30
................................................................................................................................................................................................................................................................................................................................................................................ †
Postoperative complications (n)
................................................................................................................................................................................................................................................................................................................................................................................
44.7 ⫾ 12.5
Operative time (min)*
51.0 ⫾ 20.7
.01
1 (1%)
15 (9%)
.01
11 (13%)
30 (19%)
.37
................................................................................................................................................................................................................................................................................................................................................................................
Operative time ⱖ90 min (n)
................................................................................................................................................................................................................................................................................................................................................................................ ‡
Composite maternal morbidity (n)
................................................................................................................................................................................................................................................................................................................................................................................
* Data are presented as mean ⫾ SD. †
Includes wound complications, ileus, anemia, disseminated intravascular coagulation, deep venous thrombosis, and pulmonary embolism.
‡
Includes cystotomy, disseminated intravascular coagulation, transfusion, intensive care unit admission, repeat surgery, postoperative complications, and length of stay of ⬎4 days.
sions, with an alpha of .05 and a beta of .2, 74 patients per arm were needed. Secondary outcomes were composite and individual maternal morbidities, included chorioamnionitis, disseminated intravascular coagulation, uterine atony, length of stay of ⬎4 days, postoperative fever (temperature, ⬎38°C), intensive care unit admission, repeat surgery, blood transfusion, blood loss, postoperative complications (including wound seroma, ileus, anemia, disseminated intravascular coagulation, deep venous thrombosis, pulmonary embolism), and length of surgery. Neonatal outcomes included 5-minute Apgar score of ⬍7, presence of meconium, arterial cord pH ⬍7.2, neonatal intensive care unit (NICU) admission, and NICU length of stay. All patients underwent continuous electronic fetal monitoring throughout labor. Data were entered into a STATA database (Statacorp, College Station, TX). Univariate statistical tests with the chi306.e3
square test of proportions and the Fisher’s exact test were considered statistically significant if the probability value was ⬍.05. Multivariable logistic regression analysis was used to control for potential confounding variables. We received approval for this study from the Committee on Human Research at Stanford University Medical Center.
R ESULTS Two hundred forty patients met eligibility criteria; 1 patient was not included because her chart was unavailable for review. Of the 239 patients whose cases were assessed, 82 patients had a second stage of labor that lasted 1-3 hours, and 157 patients had a second stage of labor that lasted ⬎4 hours. Maternal and neonatal demographics were similar between groups (Table 1). All hysterotomies were low transverse. Prolonged second stage of labor was associated with unintentional hysterot-
American Journal of Obstetrics & Gynecology SEPTEMBER 2007
omy extensions (Table 2). The incidence of hysterotomy extensions increased with the length of the second stage (25% at 1-3 hours, 32% at 4-5 hours, and 47% at ⬎5 hours; P ⫽ .01). Prolonged second stage of labor was associated with an increase in the incidence of hysterotomy extensions to the cervix (29% vs 5%; P ⫽ .005; Table 3). By location, hysterotomy extensions occurred most frequently in the lower uterine segment, followed by the cervix, other locations, and the broad ligament (Table 3). The occurrence of ⬎1 hysterotomy extension was not more frequent with a prolonged second stage of labor. Total operative time was longer after a prolonged second stage of labor. Cesarean deliveries more frequently lasted ⬎90 minutes among women with a prolonged second stage of labor (Table 2). There were no differences in the other studied maternal morbidities between groups, nor was there a difference in composite morbidity (Table 2).
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TABLE 3
Location of hysterotomy extensions
Location
Hysterotomy extensions with cesarean delivery after second stage that lasted 1-3 hours (n ⴝ 21)
Hysterotomy extensions with cesarean delivery after second stage that lasted >4 hours (n ⴝ 63)
Lower uterine segment (n)
19 (90%)
38 (64%)
Cervix (n)
1 (5%)
17 (29%)
.005
Broad ligament (n)
0
2 (3%)
.87
Other (n)
1 (5%)
2 (3%)
P value .87
................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................................................................................................................
A multivariable logistic regression analysis was performed that controlled for potential confounding variables (Table 4). Unintentional hysterotomy extensions were ⬎2 times more frequent with a prolonged second stage of labor and 2 times more frequent when oxytocin was used during labor, independent of the length of the second stage. The other variables that were examined were not associated independently with hysterotomy extensions. Neonatal outcomes were not significantly different between groups (Table 5).
TABLE 4
Hysterotomy extensions and prolonged second stage of labor, multivariable outcomes* Variable
Odds ratio (95% CI)
⬎4-Hour second stage 2.18 (1.13-4.22) of labor
...........................................................................................................
C OMMENT In our study, cesarean delivery after a second stage of labor that lasted ⬎4 hours was associated with unintentional hysterotomy extensions, particularly to the cervix. The risk appears to increase with the duration of the second stage, because we found a positive association between the length of a prolonged second stage of labor and the incidence of extensions. Use of oxytocin during labor also conferred an independent risk of unintentional hysterotomy extensions. Both findings were independent of attempted operative vaginal delivery, obesity, and birthweight. Prolonged labor may increase attenuation of the lower uterine segment and impaction of the fetal head, giving rise to a thin, easily lacerated lower uterine segment and cervix. Oxytocin use may be a proxy for an abnormal labor or may lead to greater attenuation of the lower uterine seg-
1.0
ment. Our findings are in contrast to those of Allen et al,13 who found an association between intraoperative trauma during cesarean delivery in second stage, compared with first stage, but not when prolonged second stage of labor of ⬎4 hours was compared with second stage of ⱕ4 hours. Operative times were increased among patients with a prolonged second stage of labor, likely because of the increased time that was needed to repair hysterotomy extensions. We did not identify an increase in any of the other maternal morbidities that we examined, which included blood loss and bladder injury, but we were not powered to identify small differences. Several recent studies have shown that prolonged second stage of labor does not affect neonatal morbidity, regardless of mode of delivery.6,7,11 We assessed a limited number of neonatal outcomes and
TABLE 5
Neonatal outcomes*
Chorioamnionitis
1.67 (0.89-3.13)
Outcome
Age ⱖ35 y
0.49 (0.24-1.00)
5-Minute Apgar score ⬍7†
Parity
0.93 (0.53-1.64)
...................................................................................................................................................................................................................................... ‡
Operative vaginal delivery attempt
0.71 (0.33-1.53)
...................................................................................................................................................................................................................................... §
Body mass index ⱖ 30 kg/m2
0.78 (0.42-1.44)
Birthweight ⱖ4000 g
0.76 (0.38-1.53)
Public insurance
0.68 (0.27-1.73)
Preeclampsia
1.61 (0.33-7.74)
........................................................................................................... ........................................................................................................... ...........................................................................................................
1-3 Hours
>4 Hours
P value
2 (2)
2 (1)
.61
Meconium
29 (42)
44 (43)
1.00
Arterial cord pH ⬍7.2
20 (50)
26 (35)
.12
Neonatal intensive care unit admission储
27 (34)
58 (37)
.67
......................................................................................................................................................................................................................................
...........................................................................................................
......................................................................................................................................................................................................................................
........................................................................................................... ........................................................................................................... ...........................................................................................................
Neonatal intensive care unit admission length of stay (days)¶ # †
N ⫽ 183.
Pitocin augmentation
N ⫽ 172.
§
N ⫽ 115.
储
N ⫽ 237.
* Variables that were controlled for: chorioamnionitis, age ⱖ 35 y, parity, operative vaginal delivery attempt, body mass index ⱖ30, birthweight ⱖ4000 g, public insurance, preeclampsia, and oxytocin augmentation.
.63
* Data were not available for all patients. ‡
2.01 (1.08-3.75)
3.3 ⫾ 2.1
......................................................................................................................................................................................................................................
........................................................................................................... ...........................................................................................................
2.9 ⫾ 1.4
¶
N ⫽ 82.
#
Data are presented as mean ⫾ SD.
SEPTEMBER 2007 American Journal of Obstetrics & Gynecology
306.e4
SMFM Papers also did not identify an increase in neonatal morbidity with prolonged second stage of labor. Of note, a large number of newborn infants in our study were admitted to the NICU, likely because it is routine practice at our institution to admit all newborn infants with the diagnosis of chorioamnionitis to the NICU for evaluation. Our study was limited by its retrospective nature. The presence and details of unintentional hysterotomy extensions relied on the surgeon’s accurate dictation. Further, because this was not a randomized study, the findings may be biased because of confounding. We attempted to control for potential confounding with multivariable logistic regression; however, residual confounding may exist because of confounders that we did not consider or abstract from the medical records. Our data may be helpful in encouraging obstetricians to modify labor management and cesarean technique and with counseling patients who are considering a prolonged second stage of labor. Greater focus and education on careful technique in delivering the fetal head and shoulders through the uterine incision after a prolonged second stage of labor may be appropriate. It is our clinical experience that, with a cesarean delivery that is performed after a prolonged second stage of labor, care should be taken to place the hysterotomy slightly higher on the lower uterine segment. The significance of unintentional hysterotomy extensions, with regard to future
306.e5
www.AJOG.org uterine rupture and cervical insufficiency, is not clear and needs further study. Intentional superior and inferior hysterotomy extensions are believed anecdotally to increase the risk for uterine rupture. Unintentional hysterotomy extensions theoretically could be associated with increased uterine rupture risk as well. Cervical insufficiency has been associated both with a prolonged second stage of labor of ⬎3 hours in a previous pregnancy15 and with cervical trauma, such as conization.16 Whether cervical hysterotomy extensions at time of cesarean delivery increase the risk of future cervical insufficiency is unknown, but plausible. The increase in hysterotomy extensions may have as yet unknown effects on future pregnancies, including increased uterine rupture risk or risk for cervical insufficiency. Both of these questions deserve further investigation. f REFERENCES 1. Friedman EA. Primigravid labor: a graphicostatistical analysis. Obstet Gynecol 1955;6: 567-89. 2. Hellman LM, Prystowsky H. The duration of the second stage of labor. Am J Obstet Gynecol 1952;63:1223-33. 3. Cohen WR. Influence of the duration of second stage labor on perinatal outcome and puerperal morbidity. Obstet Gynecol 1977;49: 266-9. 4. Kilpatrick SJ, Laros RK. Characteristics of normal labor. Obstet Gynecol 1989;74:85-7. 5. Myles TD, Santolaya J. Maternal and neonatal outcomes in patients with a prolonged second stage of labor. Obstet Gynecol 2003; 102:52-8. 6. Saunders N, Paterson CM, Wadworth J. Neonatal and maternal morbidity in relation to
American Journal of Obstetrics & Gynecology SEPTEMBER 2007
the length of the second stage of labour. BJOG 1992;99:381-5. 7. Cheng YW, Hopkins LM, Caughey AB. How long is too long: does a prolonged second stage of labor in nulliparous women affect maternal and neonatal outcomes? Am J Obstet Gynecol 2004;191:933-8. 8. O’Connell MP, Hussain J, Maclennan FA, Lindow SW. Factors associated with a prolonged second stage of labour: a case-controlled study of 364 nulliparous labours. J Obstet Gynaecol 2003;23:255-7. 9. Menticoglou SM, Manning F, Harman C, Morrison I. Perinatal outcome in relation to second-stage duration. Am J Obstet Gynecol 1995;173:906-12. 10. Paterson CM, Saunders N. The characteristics of the second stage of labour in 25069 singleton deliveries in the North West Thames health region, 1988. BJOG 1992;99:377-80. 11. Janni W, Schiessl B, Peschers U, et al. The prognostic impact of a prolonged second stage of labor on maternal and fetal outcome. Acta Obstet Gynecol Scand 2002;81:214-21. 12. Cebekulu L, Buchman EJ. Complications associated with cesarean section in the second stage of labor. Int J Gynaecol Obstet 2006; 95:110-4. 13. Allen VM, O’Connell CM, Baskett TF. Maternal and perinatal morbidity of caesarean delivery at full cervical dilatation compared with caesarean delivery in the first stage of labour. BJOG 2005;112:986-90. 14. Alexander JM, Leveno, KJ, Rouse DJ, et al. Comparison of maternal and infant outcomes from primary cesarean delivery during the second compared with first stage of labor. Obstet Gynecol 2007;109:917-21. 15. Vyas NA, Vink JS, Ghidini A, et al. Risk factors for cervical insufficiency after term delivery. Am J Obstet Gynecol 2006;195:787-91. 16. Moinian M, Andersch R. Does cervix conization increase the risk of complications in subsequent pregnancies? Acta Obstet Gynecol Scand 1982;61:101-3.