A C TA Obstetricia et Gynecologica
AOGS M A I N R E SE A RC H A R TI C LE
Management of prolonged pregnancy by induction with a Foley catheter HEIDI KRUIT1, OSKARI HEIKINHEIMO1, VELI-MATTI ULANDER1, ANSA AITOKALLIO-TALLBERG1, IRMELI NUPPONEN2, JORMA PAAVONEN1 & LEENA RAHKONEN1 1 2
Department of Obstetrics and Gynecology, University of Helsinki and Helsinki University Hospital, Helsinki, and Children’s Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
Key words Labor induction, Foley catheter, prolonged pregnancy, cesarean delivery rate, nulliparous women Correspondence Heidi Kruit, Department of Obstetrics and Gynecology, Helsinki University Hospital, Haartmaninkatu 2, 00029 HUS Helsinki, Finland. E-mail: [email protected] Conflict of interest The authors have stated explicitly that there are no conflicts of interest in connection with this article. Please cite this article as: Kruit H, Heikinheimo O, Ulander V-M, AitokallioTallberg A, Nupponen I, Paavonen J, et al. Management of prolonged pregnancy by induction with a Foley catheter. Acta Obstet Gynecol Scand 2015; 94: 608–614. Received: 30 December 2014 Accepted: 4 March 2015
Objectives. To describe labor outcomes in women with prolonged pregnancy and induction of labor with a Foley catheter, as compared with women with spontaneous onset of labor. Design. Retrospective study. Setting. Helsinki University Hospital. Sample. 553 women with uncomplicated prolonged pregnancies between January 2011 and January 2012, divided into 303 women (54.8%) with Foley catheter induction and 250 (45.2%) with spontaneous labor. Methods. Maternal and neonatal characteristics of women with uncomplicated singleton pregnancy of ≥41+5 weeks of gestation were analyzed. Main outcome measures. Cesarean delivery rates, maternal and neonatal morbidity. Results. The cesarean delivery rate was 30.7% (n = 93/303) in women with labor induction and 4.8% (12/250) in women with spontaneous onset of labor (p < 0.001). The cesarean delivery rate was 37.3% (91/244) among nulliparous women with labor induction and 8.7% (11/126) among women with spontaneous labor, a sixfold increased risk (odds ratio 6.2). Among parous women, cesarean section rates were low and not significantly different (3.4% vs. 0.8%, p = 0.2). There were no differences in maternal intrapartum or postpartum infection rates or adverse neonatal outcomes between the groups. Conclusions. Foley catheter induction of labor in prolonged pregnancy did not increase maternal or perinatal morbidity compared with spontaneous onset of labor but was associated with a considerably increased cesarean section rate, particularly among nulliparous women. Abbreviations:
GBS, Group B Streptococcus agalactiae; IOL, induction of labor.
DOI: 10.1111/aogs.12632
Introduction The World Health Organization defines post-term pregnancy as one extending to ≥42+0 weeks (≥294 days) (1). Post-term pregnancy occurs in approximately 5% of pregnancies, varying in reported frequency from 0.4 to 8.1% in different countries (2). In Finland, 8–10% of all pregnancies extend beyond 41 weeks of gestation and the rate of post-term pregnancy has ranged between 4.2 and 4.8% during recent years (3,4). Post-term pregnancy is associated with maternal and fetal risks, raised rates of operative delivery, and increased perinatal mortality (5,6).
608
Key Message Labor induction with Foley catheter in prolonged pregnancy appears as safe as spontaneous labor in terms of perinatal morbidity but is associated with a high rate of cesarean delivery, particularly among nulliparous women. Given the major impact of the first cesarean delivery on subsequent pregnancies, it is important to optimize labor induction methods, not least for nulliparous women.
ª 2015 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 94 (2015) 608–614
H. Kruit et al.
Labor induction in prolonged pregnancy
Post-term pregnancy is the most common indication for labor induction (7). Nowadays, induction of labor (IOL) is started before 42 weeks in many countries since several clinical practice guidelines on the management of postterm pregnancy recommend elective induction and delivery by 41 completed weeks (1,8,9). While induction rates have increased, the rates of post-term pregnancy have decreased (8). There is a concern that rising rates of IOL may increase cesarean deliveries (10,11). However, it has been debated whether the increased cesarean section rates are related to the IOL or to the indication(s) for induction. In a recently published Norwegian study, only insignificant increases in the cesarean section rate were seen after a change to a more liberal induction policy for prolonged pregnancies (12). Furthermore, in a recent meta-analysis the cesarean section rate in term and post-term pregnancies was lower among women with induced labor than in women managed expectantly (13). The Foley catheter method has been established for IOL since it was first described in the early 1980s. Then, it was used in conjunction with prostaglandin administration via the catheter (14). After 1990, additional studies on the use of the Foley catheter for labor induction were published. Recently, the Foley catheter has been shown to result in a comparable vaginal delivery rate to that seen following induction with prostaglandins in low-risk women with an unfavorable cervical score at term (15,16). The aim of this study was to evaluate delivery outcomes in prolonged pregnancies induced by Foley catheter.
Material and methods This retrospective study of women with a prolonged pregnancy of ≥41+5 gestational weeks between January 2011 and January 2012 (1 year) was conducted at the
Department of Obstetrics and Gynecology, Helsinki University Hospital, Finland. According to the departmental management guidelines, all women with an uncomplicated prolonged pregnancy receive an appointment for an antenatal visit in the maternity outpatient clinic at 41+5 weeks of gestation. The decision on IOL or expectant management depends on an assessment of maternal and fetal wellbeing and on maternal preference. Fetal wellbeing was examined by cardiotocography (non-stress test) and ultrasonographic assessment of fetal growth, fetal movements, and amniotic fluid volume (biophysical profile). Where expectant management was chosen, IOL was scheduled no later than 42+1 weeks (4 days later) if spontaneous labor had not commenced. Since 2010, the Foley catheter has been the main method of labor induction in our department (17). A total of 798 women with an uncomplicated singleton pregnancy ≥41+5 weeks of gestation were identified from the hospital database during the study year. Duration of pregnancy was defined by the fetal crown–rump length measurement performed at the time of first trimester ultrasound screening. We excluded 212 women with breech presentation, a history of cesarean section or previous rupture of membranes in the current pregnancy (Figure 1). Since we wanted to focus on Foley catheter induction, a relatively new IOL method in our clinic at the time, we also excluded women in whom other induction methods were used. The final database thus contained 553 deliveries, including 303 women (54.8%) with Foley catheter IOL and 250 women (45.2%) with spontaneous labor by 42+1 weeks of gestation. In all cases the main indication for IOL was prolonged pregnancy. The study protocol was approved by the local Ethics Committee (No. 268/13/03/03/2012) and the management of the Hospital district of Helsinki and Uusimaa. In Foley catheter induction a single balloon catheter (R€ usch 2-way Foley Couvelaire tip catheter size 22 Ch,
Study population n = 798 Primary exclusion (n = 212): Previous cesarean section n = 79 Breech presentation n=2 Amniotomy n = 70 Prostaglandin n = 61
Spontaneous labor n = 250
Primiparous n = 126
Multiparous n = 124
Labor induction n = 336
Primiparous n = 244
Secondary exclusion: Foley catheter + prostaglandin n = 33
Multiparous n = 59
Figure 1. Flow chart of the study population.
ª 2015 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 94 (2015) 608–614
609
Labor induction in prolonged pregnancy
Teleflex Medical, Athlone, Ireland) was used. In 139 (45.9%) cases the catheter was inserted at gestational age 41+5, in 65 women (21.5%) at 41+6, in 83 (27.4%) at 42+0 and in 16 (5.2%) at 42+1 weeks. Before inserting the catheter, a Bishop score was determined (18). At commencement of IOL all the women had unfavorable cervical scores (Bishop score ≤6). The catheter was introduced into the endocervix and towards the space between the amniotic membrane and the lower uterine segment. The balloon reservoir was inflated with 40–50 mL of saline and retracted so that it rested on the internal os. Light traction was applied and the catheter was taped on to the inner aspect of the thigh. Fetal monitoring for a minimum of 20 min was continued. After spontaneous expulsion of the balloon, amniotomy was performed if the Bishop score was ≥6. If spontaneous expulsion of the Foley catheter did not occur within 24 h, the balloon was removed. If the cervix remained unripe with a Bishop score 20 9 109/L. At least two of these criteria had to be met, combined with administration of antibiotics. Postpartum infection diagnoses included endometritis (by the above criteria), wound infection, mastitis, urinary tract infection and puerperal fever of unknown origin. Neonatal infections were categorized into blood culture positive sepsis, clinical sepsis, and suspected sepsis. Neonatal clinical sepsis was defined as a blood culture negative infection with symptoms and signs consistent with sepsis (such as respiratory distress, apnea, tachycardia, poor capillary perfusion, low blood pressure, fever, hypoor hyperglycemia, irritability, feeding problems, lethargy and convulsions), abnormal blood values (such as elevated levels of the C-reactive protein, leukocytosis or leukopenia, increased neutrophil precursors and thrombocytopenia) and positive response to a minimum of 5 days of antibiotic treatment. The cases defined as suspected sepsis had to have at least one symptom and one abnormal laboratory test value, and a positive response to antibiotic treatment. All calculations were carried out using the Microsoft Statistical Package for Social Sciences for Windows v18.0 (SPSS Inc., Chicago, IL, USA). Categorical variables were compared by the chi-squared and Fisher’s exact tests when appropriate. Data with continuous variables were analyzed by the t-test when the data followed normal distribution and by a Mann–Whitney U-test if this was not the case. We used univariate logistic regression to estimate relative risks represented by odds ratios with 95% confidence intervals. A p-value < 0.05 was considered significant.
Results The characteristics of the study population are shown in Table 1. The women with induced labor were more often nulliparous (p < 0.001) and more often had an extended gestational age of ≥42 weeks at the start of IOL (p < 0.001) compared with women with spontaneous labor onset at or after 41+5 weeks. The medians of gestational weeks at the start of IOL and spontaneous labor were, however, similar in both groups: 41.9 (range 41.7– 42.3) and 41.9 (range 41.7–42.6). Maternal outcomes are shown in Table 2. The nulliparous, but not parous, women with IOL more often received prophylactic antibiotics and epidural or spinal analgesia than women with spontaneous labor onset did (p < 0.001, p = 0.03, respectively). Oxytocin augmentation was more common in IOL cases than among women
ª 2015 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 94 (2015) 608–614
H. Kruit et al.
Labor induction in prolonged pregnancy
Table 1. Characteristics of the study population.
Maternal age ≥35 years Nulliparous IVF Smoking BMI (kg/m²)a ≥30 kg/m² Gestational diabetes Gestational age ≥42 weeks
Foley catheter induction (n = 303)
Spontaneous labor (n = 250)
n
%
n
%
p-value
65 244 7 42 34 27 197
21.5 80.5 2.3 13.9 11.2 8.9 65.0
70 126 2 35 22 22 65
28.0 50.4 0.8 14.0 8.8 8.8 26.0
0.07
AOGS M A I N R E SE A RC H A R TI C LE
Management of prolonged pregnancy by induction with a Foley catheter HEIDI KRUIT1, OSKARI HEIKINHEIMO1, VELI-MATTI ULANDER1, ANSA AITOKALLIO-TALLBERG1, IRMELI NUPPONEN2, JORMA PAAVONEN1 & LEENA RAHKONEN1 1 2
Department of Obstetrics and Gynecology, University of Helsinki and Helsinki University Hospital, Helsinki, and Children’s Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
Key words Labor induction, Foley catheter, prolonged pregnancy, cesarean delivery rate, nulliparous women Correspondence Heidi Kruit, Department of Obstetrics and Gynecology, Helsinki University Hospital, Haartmaninkatu 2, 00029 HUS Helsinki, Finland. E-mail: [email protected] Conflict of interest The authors have stated explicitly that there are no conflicts of interest in connection with this article. Please cite this article as: Kruit H, Heikinheimo O, Ulander V-M, AitokallioTallberg A, Nupponen I, Paavonen J, et al. Management of prolonged pregnancy by induction with a Foley catheter. Acta Obstet Gynecol Scand 2015; 94: 608–614. Received: 30 December 2014 Accepted: 4 March 2015
Objectives. To describe labor outcomes in women with prolonged pregnancy and induction of labor with a Foley catheter, as compared with women with spontaneous onset of labor. Design. Retrospective study. Setting. Helsinki University Hospital. Sample. 553 women with uncomplicated prolonged pregnancies between January 2011 and January 2012, divided into 303 women (54.8%) with Foley catheter induction and 250 (45.2%) with spontaneous labor. Methods. Maternal and neonatal characteristics of women with uncomplicated singleton pregnancy of ≥41+5 weeks of gestation were analyzed. Main outcome measures. Cesarean delivery rates, maternal and neonatal morbidity. Results. The cesarean delivery rate was 30.7% (n = 93/303) in women with labor induction and 4.8% (12/250) in women with spontaneous onset of labor (p < 0.001). The cesarean delivery rate was 37.3% (91/244) among nulliparous women with labor induction and 8.7% (11/126) among women with spontaneous labor, a sixfold increased risk (odds ratio 6.2). Among parous women, cesarean section rates were low and not significantly different (3.4% vs. 0.8%, p = 0.2). There were no differences in maternal intrapartum or postpartum infection rates or adverse neonatal outcomes between the groups. Conclusions. Foley catheter induction of labor in prolonged pregnancy did not increase maternal or perinatal morbidity compared with spontaneous onset of labor but was associated with a considerably increased cesarean section rate, particularly among nulliparous women. Abbreviations:
GBS, Group B Streptococcus agalactiae; IOL, induction of labor.
DOI: 10.1111/aogs.12632
Introduction The World Health Organization defines post-term pregnancy as one extending to ≥42+0 weeks (≥294 days) (1). Post-term pregnancy occurs in approximately 5% of pregnancies, varying in reported frequency from 0.4 to 8.1% in different countries (2). In Finland, 8–10% of all pregnancies extend beyond 41 weeks of gestation and the rate of post-term pregnancy has ranged between 4.2 and 4.8% during recent years (3,4). Post-term pregnancy is associated with maternal and fetal risks, raised rates of operative delivery, and increased perinatal mortality (5,6).
608
Key Message Labor induction with Foley catheter in prolonged pregnancy appears as safe as spontaneous labor in terms of perinatal morbidity but is associated with a high rate of cesarean delivery, particularly among nulliparous women. Given the major impact of the first cesarean delivery on subsequent pregnancies, it is important to optimize labor induction methods, not least for nulliparous women.
ª 2015 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 94 (2015) 608–614
H. Kruit et al.
Labor induction in prolonged pregnancy
Post-term pregnancy is the most common indication for labor induction (7). Nowadays, induction of labor (IOL) is started before 42 weeks in many countries since several clinical practice guidelines on the management of postterm pregnancy recommend elective induction and delivery by 41 completed weeks (1,8,9). While induction rates have increased, the rates of post-term pregnancy have decreased (8). There is a concern that rising rates of IOL may increase cesarean deliveries (10,11). However, it has been debated whether the increased cesarean section rates are related to the IOL or to the indication(s) for induction. In a recently published Norwegian study, only insignificant increases in the cesarean section rate were seen after a change to a more liberal induction policy for prolonged pregnancies (12). Furthermore, in a recent meta-analysis the cesarean section rate in term and post-term pregnancies was lower among women with induced labor than in women managed expectantly (13). The Foley catheter method has been established for IOL since it was first described in the early 1980s. Then, it was used in conjunction with prostaglandin administration via the catheter (14). After 1990, additional studies on the use of the Foley catheter for labor induction were published. Recently, the Foley catheter has been shown to result in a comparable vaginal delivery rate to that seen following induction with prostaglandins in low-risk women with an unfavorable cervical score at term (15,16). The aim of this study was to evaluate delivery outcomes in prolonged pregnancies induced by Foley catheter.
Material and methods This retrospective study of women with a prolonged pregnancy of ≥41+5 gestational weeks between January 2011 and January 2012 (1 year) was conducted at the
Department of Obstetrics and Gynecology, Helsinki University Hospital, Finland. According to the departmental management guidelines, all women with an uncomplicated prolonged pregnancy receive an appointment for an antenatal visit in the maternity outpatient clinic at 41+5 weeks of gestation. The decision on IOL or expectant management depends on an assessment of maternal and fetal wellbeing and on maternal preference. Fetal wellbeing was examined by cardiotocography (non-stress test) and ultrasonographic assessment of fetal growth, fetal movements, and amniotic fluid volume (biophysical profile). Where expectant management was chosen, IOL was scheduled no later than 42+1 weeks (4 days later) if spontaneous labor had not commenced. Since 2010, the Foley catheter has been the main method of labor induction in our department (17). A total of 798 women with an uncomplicated singleton pregnancy ≥41+5 weeks of gestation were identified from the hospital database during the study year. Duration of pregnancy was defined by the fetal crown–rump length measurement performed at the time of first trimester ultrasound screening. We excluded 212 women with breech presentation, a history of cesarean section or previous rupture of membranes in the current pregnancy (Figure 1). Since we wanted to focus on Foley catheter induction, a relatively new IOL method in our clinic at the time, we also excluded women in whom other induction methods were used. The final database thus contained 553 deliveries, including 303 women (54.8%) with Foley catheter IOL and 250 women (45.2%) with spontaneous labor by 42+1 weeks of gestation. In all cases the main indication for IOL was prolonged pregnancy. The study protocol was approved by the local Ethics Committee (No. 268/13/03/03/2012) and the management of the Hospital district of Helsinki and Uusimaa. In Foley catheter induction a single balloon catheter (R€ usch 2-way Foley Couvelaire tip catheter size 22 Ch,
Study population n = 798 Primary exclusion (n = 212): Previous cesarean section n = 79 Breech presentation n=2 Amniotomy n = 70 Prostaglandin n = 61
Spontaneous labor n = 250
Primiparous n = 126
Multiparous n = 124
Labor induction n = 336
Primiparous n = 244
Secondary exclusion: Foley catheter + prostaglandin n = 33
Multiparous n = 59
Figure 1. Flow chart of the study population.
ª 2015 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 94 (2015) 608–614
609
Labor induction in prolonged pregnancy
Teleflex Medical, Athlone, Ireland) was used. In 139 (45.9%) cases the catheter was inserted at gestational age 41+5, in 65 women (21.5%) at 41+6, in 83 (27.4%) at 42+0 and in 16 (5.2%) at 42+1 weeks. Before inserting the catheter, a Bishop score was determined (18). At commencement of IOL all the women had unfavorable cervical scores (Bishop score ≤6). The catheter was introduced into the endocervix and towards the space between the amniotic membrane and the lower uterine segment. The balloon reservoir was inflated with 40–50 mL of saline and retracted so that it rested on the internal os. Light traction was applied and the catheter was taped on to the inner aspect of the thigh. Fetal monitoring for a minimum of 20 min was continued. After spontaneous expulsion of the balloon, amniotomy was performed if the Bishop score was ≥6. If spontaneous expulsion of the Foley catheter did not occur within 24 h, the balloon was removed. If the cervix remained unripe with a Bishop score 20 9 109/L. At least two of these criteria had to be met, combined with administration of antibiotics. Postpartum infection diagnoses included endometritis (by the above criteria), wound infection, mastitis, urinary tract infection and puerperal fever of unknown origin. Neonatal infections were categorized into blood culture positive sepsis, clinical sepsis, and suspected sepsis. Neonatal clinical sepsis was defined as a blood culture negative infection with symptoms and signs consistent with sepsis (such as respiratory distress, apnea, tachycardia, poor capillary perfusion, low blood pressure, fever, hypoor hyperglycemia, irritability, feeding problems, lethargy and convulsions), abnormal blood values (such as elevated levels of the C-reactive protein, leukocytosis or leukopenia, increased neutrophil precursors and thrombocytopenia) and positive response to a minimum of 5 days of antibiotic treatment. The cases defined as suspected sepsis had to have at least one symptom and one abnormal laboratory test value, and a positive response to antibiotic treatment. All calculations were carried out using the Microsoft Statistical Package for Social Sciences for Windows v18.0 (SPSS Inc., Chicago, IL, USA). Categorical variables were compared by the chi-squared and Fisher’s exact tests when appropriate. Data with continuous variables were analyzed by the t-test when the data followed normal distribution and by a Mann–Whitney U-test if this was not the case. We used univariate logistic regression to estimate relative risks represented by odds ratios with 95% confidence intervals. A p-value < 0.05 was considered significant.
Results The characteristics of the study population are shown in Table 1. The women with induced labor were more often nulliparous (p < 0.001) and more often had an extended gestational age of ≥42 weeks at the start of IOL (p < 0.001) compared with women with spontaneous labor onset at or after 41+5 weeks. The medians of gestational weeks at the start of IOL and spontaneous labor were, however, similar in both groups: 41.9 (range 41.7– 42.3) and 41.9 (range 41.7–42.6). Maternal outcomes are shown in Table 2. The nulliparous, but not parous, women with IOL more often received prophylactic antibiotics and epidural or spinal analgesia than women with spontaneous labor onset did (p < 0.001, p = 0.03, respectively). Oxytocin augmentation was more common in IOL cases than among women
ª 2015 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 94 (2015) 608–614
H. Kruit et al.
Labor induction in prolonged pregnancy
Table 1. Characteristics of the study population.
Maternal age ≥35 years Nulliparous IVF Smoking BMI (kg/m²)a ≥30 kg/m² Gestational diabetes Gestational age ≥42 weeks
Foley catheter induction (n = 303)
Spontaneous labor (n = 250)
n
%
n
%
p-value
65 244 7 42 34 27 197
21.5 80.5 2.3 13.9 11.2 8.9 65.0
70 126 2 35 22 22 65
28.0 50.4 0.8 14.0 8.8 8.8 26.0
0.07
