Induction of Labor: A Comparison of Guidelines

Article Information

Muneera Ahmed AlKhalifa1, Stephanie Hsu2, Nusiba ElHassan3, Basma AlAnsari3, Rehab Ismael3, Gulmeen Raza3, Hosni Malas4, Mahmoud Samy Ismail3*

1King Hamad University Hospital (KHUH), Al Sayh, Bahrain

2East Kent University Hospitals Foundation, NHS, United Kingdom

3Department of Obstetrics and Gynecology, King Hamad University Hospital (KHUH), Al Sayh, Bahrain

4Head of Department of Obstetrics and Gynecology, King Hamad University Hospital (KHUH), Al Sayh, Bahrain

*Corresponding Author: Mahmoud Samy Ismail, OB/GYN Department, King Hamad University Hospital, Building 2435, Road 2835, Block 228, Busaiteen P.O Box 24343, Al Muharraq, Kingdom of Bahrain

Received: 14 February 2022; Accepted: 22 February 2022; Published: 10 March 2022

Citation:

Muneera Ahmed AlKhalifa, Stephanie Hsu, Nusiba ElHassan, Basma AlAnsari, Rehab Ismael, Gulmeen Raza, Hosni Malas, Mahmoud Samy Ismail. Induction of Labor: A Comparison of Guidelines. Obstetrics and Gynecology Research 5 (2022): 081-106.

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Abstract

Introduction: Induction of labor (IOL) is a com-monly performed obstetric procedure that initiates labor prior to its spontaneous onset. It is advised when the benefits of terminating the pregnancy outweigh the risks of ongoing pregnancy.

Aim: This is a review article that compares the most recent international guidelines on IOL by organizations including World Health Organization (WHO), the National Institute for Health and Care Excellence (NICE), American College of Obstetricians and Gynecologists (ACOG), the Society of Obstetricians and Gynecologists of Canada (SOGC), the Federation of Obstetric and Gynecological Societies of India (FOGSI) and Queensland Health. We will also compare these recommendations to the current guidelines set in our institute, King Hamad University Hospital (KHUH) in the Kingdom of Bahrain.

Conclusion: The most notable differences were observed in the Bishop scoring with minor differences in the methods of induction and management of complications. Improving KHUH guidelines in particular areas would enhance patient care. Regular audits are essential to ensure practice is consistent with the guidelines.

Keywords

Induction of Labor (IOL), Vaginal Delivery, Cesarean Section, Guidelines for Inducing Labor, Bishop Score

Induction of Labor (IOL) articles; Vaginal Delivery articles; Cesarean Section articles; Guidelines for Inducing Labor articles; Bishop Score articles

Article Details

Abbreviations:

ACOG: American College of Obstetrics and Gynecology; AF: Amniotic Fluid; APH: Antepartum Haemorrhage; ARM: Artificial Rupture of Membranes; BMI: Body Mass Index; CS: Cesarean Section; CTG: Cardiotocograph; D&C: Dilatation and Curettage; DIC: Disseminated Intra-vascular Coagulation; DM: Diabetes Mellitus; EFW: Estimated Fetal Weight; FHR: Fetal Heartrate; FOGSI: Federation of Obstetric and Gynecological Societies of India; GA: Gestational Age; GBS: Group B Streptococcus; GDM: Gestational Diabetes Mell-itus; HTN: Hypertension; IOL: Induction of Labor; IUFD: Intrauterine Fetal Death; IUGR: Intrauterine Growth Restriction; IV: Intravenous; KHUH: King Hamad University Hospital; LMWH: Low Molecular Weight Heparin; MgSO4: Magnesium Sulfate; NICE: National Institute for Health and Care Excellence; NICU: Neonatal Intensive Care Unit; NST: Non-Stress Test; NYHA: New York Heart Association; OHA: Oral Hypoglycaemic Agents; PET: Pre-eclamptic Toxemia; PG: Prostaglandin; PGE2: Prost-aglandin E2; PPH: Post-partum Haemorrhage; PPROM: Preterm Pre-labor Rupture of Membranes; PROM: Pre-labor Rupture of Membranes; RCOG: Royal College of Obstetricians and Gynaecologists; SOGC: Society of Obstetricians and Gynaecologists of Canada; VBAC: Vaginal Birth After Cesarean; VE: Vaginal Examination; WHO: World Health Organization.

1. Introduction

Induction of labor (IOL) is the process of artificially stimulating labor prior to its spontaneous onset ultimately achieving vaginal delivery [1-5]. It is the most common obstetric intervention, performed in almost 20% of pregnancies in the United Kingdom and the United States [2, 6, 7]. IOL is performed when the benefits outweigh the risks of continuing pregnancy [1-4, 6, 8]. When compared to spont-aneous labor, induced labor is associated with a higher incidence of additional interventions such as fetal monitoring but no increase in instrumental births. And, when comparing IOL to expectant mana-gement, there is no increase in neonatal intensive care unit (NICU) admissions or maternal mortality [3].

IOL after 37 weeks leads to improved perinatal outcomes without increasing Cesarean section (CS) rates [9]. However, women are at a higher risk of CS when undergoing IOL compared to spontaneous labor [4]. Nulliparous women, in particular, are twice as likely to deliver through CS [2]. Several factors are found to be associated with the success of IOL including maternal age, parity, body mass index (BMI), pre-existing medical conditions and Bishop score [4, 7, 9]. Age more than 35 years, BMI > 40kg/m2, estimated fetal weight (EFW) > 4kg and diabetes mellitus (DM) are associated with a higher risk of CS when labor is induced. In the presence of those unfavourable circumstances, it might be best to delay intervention and allow labor to progress spontaneously [4]. There are many variations in the recommendations proposed by health organizations globally, especially in terms of indications and contraindications of IOL, the Bishop scoring system, methods of induction and how patients should be monitored during IOL. We aim to compare several of the most recently updated international guidelines by the World Health Organization (WHO), National Institute for Health and Care Excellence (NICE), American College of Obstetricians and Gynecologists (ACOG), the Society Of Obstetricians And Gyneco-logists of Canada (SOGC), the Federation of Obstetric and Gynecological Societies of India (FOGSI) and Queensland Health, along with the current guidelines in our institute (King Hamad University Hospital (KHUH)) on the approach to ind-uction of labor.

2. Induction of Labor: A Comparison of Current Guidelines

2.1 Pre-Induction assessment

Prior to induction, women should be provided with relevant information to allow her to make an infor-med decision [3, 7, 8]. Such information includes the indication for IOL in her case, the method and its risks and benefits, an overview of the process, the risks of refusing IOL and alternative options [2-4, 7, 8] (Table 1). Women should be given a chance to consider their options and make an informed decision before giving consent [3, 4, 7, 8]. A woman who refuses IOL should have her decision respected and documented [3, 7]. The physician must, in turn, formulate a plan for ongoing care [3].

Treatment should be tailored to a woman’s personal needs and preferences, and so, effective commun-ication and informed decision-making are essential [4, 7, 8]. Patients need to be educated that most women undergo spontaneous labor before 42 weeks. At 38 weeks, they should be taught about the risks of continuing pregnancy beyond 42 weeks and what options are available [7]. Membrane sweeping incre-ases the chance of spontaneous labor, thus reducing the need for formal IOL [4, 7]. The mother’s medical and surgical history must be reviewed. In addition, the indications and contraindications to IOL must be recorded [3, 8]. Several clinical parameters should also be established within the patient’s file. They include physical examination, vital signs, and gestat-ional age (GA) [1-4, 8]. Bishop score [3, 4, 8] and electronic fetal monitoring help to determine the baby’s physical condition before IOL [7, 8] (Table 1). Besides the Bishop score, fetal fibronectin and transvaginal ultrasound have been found to predict successful IOL but are not as effective [4].

2.2 Indications for induction of labor

IOL is indicated for maternal, fetal or pregnancy-related conditions [6]. Maternal conditions include thrombophilia, DM, and renal disease among others [1, 2, 4, 6]. Fetal conditions include intrauterine growth restriction (IUGR) and intrauterine fetal death (IUFD) [1-4, 6, 8]. Pregnancy-related conditions include post-term pregnancy, oligohydra-mnios, chorioamnionitis or gestational hypertension (HTN) [1-4, 6]. High priority indications include pre-eclamptic toxemia (PET), severe maternal disease not responding to treatment, severe but stable antepartum haemorrhage (APH) and pre-labor rupture of membranes (PROM) with group B streptococcus (GBS) colonization [2, 4, 8] (Table 2). Post-term pregnancy is considered one of the most common indications for IOL [4]. IOL is indicated at 41 weeks in those with an uncomplicated pregnancy, even in patients with only gestational diabetes mellitus (GDM). Inducing labor at this GA, otherwise known as full term, leads to less perinatal deaths and CS rates [1, 3]. Studies have shown that 73% of patients who are induced for prolonged pregnancy will choose IOL the next time while only 38% of women who chose to wait for labor to start will also choose to wait the next time. Terminating pregnancy before 42 weeks leads to lower perinatal morbidity and mort-ality but not higher CS rates [4]. Queensland Health does not recommend waiting until after 42 weeks [3].

For women with PROM, IOL is indicated after 37 weeks as it is associated with reduced maternal morbidity due to infection and increased maternal satisfaction without increasing operative vaginal delivery, CS rates or NICU admissions [1, 7, 8]. Induction with vaginal prostaglandin E2 (PGE2) can be offered at 24 hours after PROM however expectant management is still a feasible option [2, 7]. Although oxytocin is associated with higher CS rates, it is more effective than expectant management to reduce maternal infection and increase vaginal delivery. Planned delivery results in a lower inci-dence of chorioamnionitis, endometritis, and NICU admissions compared to expectant management [2, 4]. In IUGR, there are pathophysiological factors that impair the growth of the fetus [3]. Induction is indicated for IUGR to prevent stillbirth. Timing depends on the severity, GA and Doppler parameters on fetal monitoring [3, 8]. Increased fetal surveillance is required when adhering to expectant management [3]. Thus, women with IUFD should be provided with support throughout the process. They should be offered the option to be immediately induced or managed expectantly [7, 8]. The method and timing depend on the GA, maternal history and preference [2]. Immediate delivery is indicated in the case of sepsis, placental abruption or PET [7, 8]. Labor starts spontaneously in more than 90% of women within 3 weeks of diagnosis. Disseminated intravascular coagulation (DIC) occurs in 25% of patients with IUFD lasting for more than 4 weeks. However, women should still be tested for DIC twice per week if IOL is delayed for more than 48 hours [8]. Misoprostol can be used between 24 and 28 weeks. Beyond 28 weeks, dilatation and curettage (D&C) is an option but cannot provide information on autopsy [2]. FOGSI recommends the use of PGE2 and oxytocin for induction [8]. There is an increased risk of uterine rupture in the case of IUFD with previous CS. This implies a reduced dose of vaginal prost-aglandin (PG), especially in the third trimester [7].

Furthermore, WHO, NICE, and ACOG do not have any recommendations to induce women with uncom-plicated twin pregnancy [1, 2, 7]. FOGSI and Queensland Health, on the other hand, recommend IOL at 37 weeks for uncomplicated twin pregnancy [3, 8]. Contraindications include monoamniotic twins and the first twin being in a non-cephalic presentation [8]. SOGC recommends delivery of uncomplicated twin pregnancy at 38 weeks or onwards [4]. A woman with a previous CS should be informed of the probability of delivering vaginally and the associated risk of uterine rupture. Management of such patients can be in the form of expectant management, CS or IOL with vaginal PGE2 [7, 8]. More than 60% of IOL in previous CS culminate with vaginal delivery. Amniotomy followed by oxytocin is preferred for a favourable cervix whereas mechanical methods followed by amniotomy and oxytocin are recomme-nded for an unfavourable cervix [8]. In the case of preterm pre-labor rupture of membranes (PPROM), IOL is not advised prior to 34 weeks unless there are certain indications such as chorioamnionitis or fetal compromise. Induction is indicated if PPROM occurs after 34 weeks. Magnesium Sulfate (MgSO4) is advised for neuroprotection if delivering prior to 32 weeks along with the provision of antenatal steroids and antibiotics if necessary. While the steroids take action, tocolysis may be used to delay delivery [8]. NICE recommends IOL with vaginal PGE2. However, there remains a risk of sepsis and possible need for CS, both of which must be considered prior to induction [7]. Ultrasound can be used to estimate fetal weight [3]. IOL solely for fetal macrosomia is not a justified indication according to WHO, SOGC and Queensland Health [1, 3, 4, 7]. IOL for obstetric cholestasis is indicated at 37-38 weeks to improve perinatal outcomes. Delivery might be indicated earlier, at 36 weeks, based on the severity of biochemical abnormalities such as jaundice, elevated liver enzymes and compromised fetal state [3, 8].

2.3 Contraindications to induction of labor

The contraindications to IOL are the same as those for labor or vaginal delivery [2-4, 8]. Common con-traindications include placenta or vasa praevia, abnormal fetal presentation, previous surgeries invol-ving the uterus, prior uterine rupture or invasive cervical carcinoma [4, 8]. IOL is not indicated when it is merely convenient to either the patient or healthcare provider [4, 7, 8]. IOL is not recom-mended for a baby in breech presentation but can be offered if a woman refuses external cephalic version or elective CS. It is also not recommended for severe IUGR [7].

2.4 Setting of induction of labor

Patients who are chosen to undergo outpatient IOL must be carefully chosen based on set criteria [2, 3]. Because IOL places more strain on the labor and delivery room compared to spontaneous labor, IOL is usually performed during the day [7]. This leads to lower operative vaginal deliveries, lower require-ments for oxytocin infusions and higher maternal satisfaction [4, 7]. It should be performed in a facility that has the capacity to monitor the wellbeing of both the mother and baby as well as equipped to perform CS [1, 3, 8]. If IOL is performed on an outpatient basis, then balloon catheters are a safer method compared to PG due to the risk of uterine hypersti-mulation in the latter [3]. ACOG considers mech-anical methods to be more appropriate while PGE2 gel is also safe [2]. For low-risk pregnancies, contin-uous electronic fetal monitoring is required 1-2 hours after administering PG and intermittent auscultation is necessary when active labor starts [4]. The process of outpatient IOL must be frequently audited and needs to be further studied with the intention of reducing the time women spend in the hospital [7]. Conversely, WHO does not recommend outpatient IOL [1].

2.5 Bishop score

The Bishop score is a pre-labor scoring system that assesses the station, dilation, effacement, position and consistency of the cervix [5, 7]. This helps guide which method(s) to use [2, 3] as well as predict the success of induction [4, 8]. A favourable cervix can either suggest a higher chance of spontaneous labor or higher response to interventions of IOL [3, 7]. The most important criteria are cervical dilation then effacement with cervical consistency being the least significant [4]. Inducing a woman with an unfavo-urable cervix is associated with higher CS rates and higher failure rates particularly in nulliparous women [4]. As per ACOG, SOGC and Queensland Health, a favourable cervix has a score of 7 or more while FOGSI considers a score of 6 or more as favourable [2-4, 8]. A score of more than 8 implies that the probability of vaginal delivery after induction is similar to that of spontaneous labor as per NICE gui-

delines [2, 4, 7] (Table 3).

2.6 Methods of induction

There are non-pharmacological, pharmacological or mechanical methods of inducing labor [4, 6]. Cervical ripening is intended to facilitate the process of softening, thinning and dilating the cervix hence reducing both the rate of failed induction and the time from induction to delivery [2, 3]. Cervical remo-deling is a normal process of parturition characterized by the breakdown and rearrangement of collagen, changes in glycosaminoglycans, infiltration of white blood cells and increased production of cytokines. If the cervix is unfavourable, as per the Bishop score, then agents for cervical ripening may be used. Using pharmacological methods to ripen the cervix does not increase CS rates [2]. The following interventions are still associated with their respective complications; hence it is crucial to inform the mother in the decision-making process [1, 4].

2.6.1 Membrane sweeping: Membrane sweeping is performed by passing a finger through the cervix, during vaginal examination, and rotating against the uterine wall while separating the chorionic membrane from the decidua thus stimulating local PG pro-duction [3, 4, 7]. It improves the initiation of labor and is especially recommended for non-urgent cases since the interval between sweeping and the start of labor is longer than other methods [8]. It can be offered to nulliparous women at 40-41 weeks ges-tation or to parous women at 41 weeks [7, 8]. If it is difficult to pass a finger through the cervix, massa-ging around the cervix in the vaginal fornices can result in similar effects [3, 4, 7]. It can reduce formal IOL by up to 33% [1, 4]. It can also be repeated if labor does not start spontaneously [3, 4, 7, 8]. Risks associated with membrane sweeping include discomfort, vaginal bleeding and PROM [1-4, 7].

2.6.2 Amniotomy: Amniotomy is the process of artificially rupturing the membranes to hasten deli-very [3]. It is recommended in the case of a favour-able cervix [2-4] and can be performed with the use of oxytocin [2-4, 6, 8]. It creates a commitment to delivery but is not recommended as a sole method of IOL [2-4, 8]. Serial membrane sweeping can be done every 2 days. Women are advised to empty their bladder before the procedure [3]. When performing an amniotomy, one must control the flow of amniotic fluid with their fingers, noting the color and amount of fluid [3, 4, 8]. CTG should be performed in the event of abnormal liquor [3]. A rapid flow of fluid leads to sudden decom-pression of the uterus which in turn can lead to placental abruption [8]. It is contraindicated in the case of placenta or vasa previa and active genital infection [2, 4]. NICE guidelines do not recommend the combination of amniotomy with oxytocin as a primary method of IOL due to the risk of uterine hyperstimulation [7].

2.6.3 Prostaglandin E2: PGE2 dissolves the struc-tural network of collagen in the cervix [4]. It is recommended for use in patients with an unfavo-urable cervix and can reduce their risk of CS [3, 4 ,8]. Prostaglandins can be administered in the form of vaginal gels/tablets or pessaries [1, 3, 4, 6, 8]. Vaginal preparations are easier to administer than cervical preparations and result in a quicker delivery [4, 8]. However, women should be informed of the associated risk of uterine hyperstimulation [7]. PGE2 gel is associated with less uterine hyperstimulation compared to tablet form. Starting with a minimal dose of PGE2 decreases the risk of uterine hyper-stimulation with FHR changes and NICU admissions compared to a high dose [1]. It should not be given to women with previous CS due to the risk of uterine rupture [3, 4]. Women with ruptured membranes are more susceptible to chorioamnionitis and uterine tachysystole if given PGE2 [3, 8]. PGE2 has the advantage of a lower operative rate compared to oxytocin and a reduced need for augmentation by oxytocin when used in an unfavourable cervix [4]. Vaginal PGE2 pessary can be easily removed in the case of uterine hyperstimulation [2, 3, 8]. It releases PG at a slower rate, of 0.3 mg/hour, than gel and does not require repeat doses [2, 3]. Otherwise, it should be removed after 24 hours or when active labor begins [8]. PGE2 should not be combined with oxytocin due to the fear of uterine hyperstimulation. If three doses of PGE2gel fail to ripen the cervix, then balloon catheter is recommended. If the PGE2 pessary fails to do so, then either PGE2 gel or balloon catheter are recommended [3]. PGE2 is a bronchodilator but is not contraindicated in patients with asthma [2, 4].

2.6.4 Oxytocin: Oxytocin is a synthetic polypeptide hormone used to stimulate uterine contractions [2, 3]. It is mostly used to induce labor in women with a favourable cervix and ruptured membranes [3, 8]. Patients with lower BMI, higher parity, and GA are more successfully induced with oxytocin [2]. It is associated with less vaginal births that extend beyond 24 hours of IOL, less NICU admissions but higher CS rates when compared to expectant management [1]. Oxytocin can be used with caution in women with previous CS due to the increased risk of uterine rupture [3, 4, 8]. It can be used alone or combined with amniotomy to either induce or augment labor [3, 8]. If PG is unavailable, IV oxytocin can be used alone for IOL [1]. However, NICE guidelines advise against using oxytocin alone for IOL [7]. Oxytocin is administered by slow intravenous (4) infusion thus allowing the control of the dose administered [2, 3, 6, 8]. The unit used to monitor the dose is milliunits per minute (mU/min) [3, 4, 8]. It should not be admini-stered as an IV bolus because even 0.5U can cause hypotension [2, 4]. The physiological dose of oxy-tocin required to stimulate uterine contractions is 8-12 mU/min [4]. Women react differently to oxytocin depending on the duration of pregnancy and their sensitivity to the drug [2]. Those who are 35 years or older require oxytocin at higher doses over a longer duration for successful vaginal delivery [9]. Oxytocin can be discontinued once labor actively starts with the cervix dilated at 5cm or more. This leads to lower uterine hyperstimulation and FHR abnormalities [3]. There is a low and high-dose regi-men for admin-istering oxytocin as per ACOG, SOGC and FOGSI (Table 5). A low-dose regimen can be used for cervical ripening in an unfavourable cervix and is associated with a lower risk of tachysystole. A high-dose regimen shortens the duration of labor but increases the risk of uterine tachysystole with FHR changes [2, 4, 8]. The uterus reacts to oxytocin 3-5 minutes after the infusion starts and its level remains steady in plasma at 40 minutes [2]. If 32 mU/min of oxytocin has been administered and labor has not started, obstetrician review is required [3].

2.6.5 Misoprostol and mifepristone: Misoprostol, a synthetic PGE1 analogue, is effective in ripening the cervix and inducing labor in an unfavourable cervix [2, 4]. It is characterized by its low cost and rapid onset of action [4]. It can be administered either orally or vaginally and both administrations result in lower CS rates; the former requires more stimulation by oxytocin while the latter is more associated with uterine tachysystole [2, 4]. However, when compared to other PG, vaginal misoprostol can be associated with a higher risk of uterine hyperstimulation with FHR changes. Lowering the dose of vaginal miso-prostol can reduce this risk [1, 2, 4]. However, this might increase the need for oxytocin stimulation. When administering oral misoprostol, patients must be told to swallow quickly to avoid sublingual absorption [4]. Queensland Health does not recom-mend the use of misoprostol for live birth [3]. Both oral and vaginal misoprostol are found to be associated with a lower risk of vaginal birth more than 24 hours after IOL, less CS and less infants with low APGAR score compared to expectant manage-ment or IV oxytocin alone [1, 2]. Misoprostol is not for use in patients with previous CS due to the associated risk of uterine rupture [1, 2, 4]. Its use is also associated with meconium-stained amniotic fluid [2, 4]. NICE recommends the use of oral mifep-ristone followed by either vaginal PGE2 or misopro-stol [7]. Misoprostol, oral or vaginal, and mifeprist-one are recommended as methods of IOL in the case of IUFD [1, 7]. In the case of fetal death, vaginal misoprostol is preferred to oral misoprostol [1].

2.6.6 Laminaria tents and balloon catheters: Mechanical methods of IOL include laminaria tents and balloon catheters [1, 6]. These methods aim to ripen and dilate the cervix to by applying pressure onto the internal cervical os [2-4, 6]. This indirectly increases the secretion of PG, oxytocin or both thus leading to the start of uterine contractions [3, 4, 6]. Laminaria tents and balloon catheters result in a lower risk of uterine hyperstimulation with FHR changes compared to PG [1, 3]. These methods are considered low cost, simple to use, reversible, and associated with less side effects [3, 4]. Balloon catheters result in fewer CS rates than oxytocin and can be used in women with previous CS since they do not increase the risk of uterine rupture [1, 3, 4, 8]. Combining the balloon catheter with oxytocin is a possible alternative if PG is unavailable but that would not shorten the time of delivery [1, 2, 8]. When comparing balloon catheters to PG, the former is associated with shorter induction-to-delivery time but increased the need for further stimulation by oxytocin, whereas PG is more associated with tachysystole while both result in similar CS rates [2-4]. Balloon catheters are absolutely contraindicated in low-lying placenta and relatively contraindicated in APH and ruptured membranes [2-4, 8]. NICE guidelines do not recommend such mechanical methods for IOL [7].

A balloon catheter can be inserted for IOL at term if the cervix is unfavourable [2, 6]. In a balloon catheter, a Foley catheter is inserted into the cervical canal and a balloon is inflated in the extra-amniotic space [3, 4, 6]. The catheter should be placed under tension to pull against the cervical os; taping the catheter to the inside of the thigh can maintain such traction [3, 4, 6, 8]. A possible option is infusing saline into the extra-amniotic space [2, 4, 6]. A double balloon catheter can also be used following a similar concept except with another balloon in the vagina against the external cervical os [2-4, 6]. It can be a second line alternative [4]. With both balloons inflated and squeezing the cervix, cervical ripening occurs due to the local release of PG. Double balloon catheter is associated with lower uterine tachysystole and less non-reassuring FHR compared to PG gel [6]. The balloon catheter is meant to remain in place for 12-24 hours [3, 8]. It is associated with a lower risk of uterine tachysystole and less non-reassuring FHR compared to PG gel [6, 8]. But it should be deflated and removed if labor begins, membranes rupture, spontaneous expulsion of device occurs or if the fetus is in distress [3, 6-8]. If labor does not start after leaving a balloon catheter for 12 hours, then amniotomy should be performed followed by oxytocin infusion [6]. If the balloon catheter fails in ripening the cervix, then PGE2 gel or pessary are recommended [3].

2.7 Monitoring during induction of labor

Labor progresses differently in IOL compared to spontaneous labor [2]. Both the mother and baby must be closely monitored for fetal distress, uterine hyperstimulation or rupture [1, 3, 8]. FHR needs to be monitored by cardiotocograph (CTG) continu-ously while receiving oxytocin, for 30 minutes after administering misoprostol, for 30 minutes to 2 hours after administering PGE2 and during active labor [1-4, 7, 8]. Intermittent auscultation can also be used after discontinuing CTG [7, 8]. FHR should also be monitored before and after artificial rupture of membranes (ARM), after inserting a balloon catheter and during failed induction [2-4, 7, 8] (Table 5). Women receiving oxytocin, misoprostol or PG should not be left unattended [1]. After starting IV oxytocin, infusion rates of oxytocin and subsequent uterine response must be continuously monitored [1-3, 8], as well as complications such as hyponatremia, uterine hyperstimulation, or rupture [3, 8]. Both the mother and fetus need to be monitored after inserting a balloon catheter with non-stress test (NST) right after insertion and 30 minutes after [6]. Maternal vital signs need to be monitored before IOL, after administering PGE2 and oxytocin and then hourly and in the case of failed IOL [1-3, 7, 8]. Women can mobilize 30 minutes after PGE2 administration [2, 3, 8]. Bishop score should be rechecked 6 hours after vaginal PGE2 gel/tablet or 24 hours after controlled-release pessary [3, 7] (Table 5). Once active labor initiates, closer monitoring is required since IOL is more painful than spontaneous labor [6-8]. Hence the need for preparation of epidural analgesia in advance [6]. Labor in the water can be effective for pain relief [7]. Women should be counselled on the available options and their implications on labor and taught breathing and relaxation techniques [7, 8]. If a woman at more than 42 weeks of gestation refuses IOL, she should be advised to undergo continuous CTG at least twice weekly after being informed of post term risks [3, 4, 7, 10].

2.8 Complications of induction of labor

After 42 weeks, the risk of stillbirth and fetal compromise rise by two-thirds compared to 37 weeks [7]. Mothers are at risk of developing chorioa-mnionitis, uterine rupture [4], and intrauterine sepsis in pregnancies that extend beyond the rupture of membranes [7]. Uterine rupture can occur in women with previous CS but also in an unscarred uterus. It can also occur in cases of multiparity, malpresent-ation or increased use of uterotonics [4, 8]. When it occurs, the mother and fetus need to be closely monitored and arranged for an emergency CS [3, 7, 8] as it is life-threatening to both the mother and baby. When using oxytocin for IOL, post-partum haemorrhage (PPH) is a risk [3]. Water intoxication due to oxytocin is only associated with high concen-trations [2]. Uterine hyperstimulation is defined as uterine contractions of more than 60 seconds or at least 4 contractions in 10 minutes [1, 4]. It is associa-ted with the use of both oxytocin, especially high-dose regimens, and PGE2 which can lead to uterine rupture or placental abruption [2-4, 7, 8]. When

uterine hyperstimulation occurs, the first step is to stop the oxytocin infusion or withdraw the PGE2 pessary to reverse uterine tachysystole [2-4, 8]. Continuous fetal monitoring with CTG is necessary [3]. The mother should be kept on her left side and monitored for changes in vital signs [2, 3]. Tachysystole is defined as more than 5 contractions every 10 minutes over 30 minutes; it can also be accompanied by FHR changes [2, 4]. Hypertonus, on the other hand, is defined as excessive uterine contractions that last more than 2 minutes without any changes in FHR [4].

The use of tocolytics can help reduce the risks of hyperstimulation if there is no improvement in FHR [1, 2, 4, 7, 8]. Options include terbutaline, salbutamol or sublingual nitroglycerin spray [2-4]. Terbutaline demonstrates a lower risk of failure compared to nitroglycerin or MgSO4 [1]. Tocolytics are not indicated if there is no evidence of fetal compromise with excessive uterine contractions. If FHR does not return to baseline, CS might be required [3]. Cord prolapse is associated with ARM [2-4]. Vaginal examination (VE) needs to be performed to rule out cord prolapse [3]. The risk of cord prolapse may be reduced by assessing whether the fetal head is engaged and palpating for umbilical cord present-ation during VE without dislodging the baby’s head [2-4, 7]. ARM should be avoided when the baby’s head is high [3, 4, 7]. It is also important to check for low-lying placenta before membrane sweeping or IOL [7]. Another possible complication of IOL is failed induction; this occurs when labor does not start after one cycle of IOL [1, 4, 7]. At least 12-18 hours after induction should pass before classifying failed induction [2]. When this occurs, it does not immediately indicate CS [1, 4]. It might in fact be failure of progress of labor, rather than failed induction [8]. If IOL is unsuccessful, then a physician must re-evaluate the indication and method then reassess the patient [3, 4, 7, 8]. Patients might be indicated for trial of an alternative method of induction [3, 7, 8]. In terms of delivery, patients might be required to undergo operative vaginal delivery or CS as a last resort [3, 4, 7, 8]. The management of the different complications of IOL is described on Table 6.

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Table 1: Pre-Induction Assessment.

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Table 2: Indications of Induction of Labour.

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Table 3: Bishop Score.

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Table 4: Methods of Induction.

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Table 5: Monitoring during Induction of Labour.

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Table 6: Complications of Induction of Labour.

3. Summary of Current Guidelines

3.1 WHO guidelines

The WHO does not provide recommendations for counseling during the pre-induction assessment or mention any contraindications to IOL. Moreover, there are no specifications regarding the Bishop scoring system and preferencing of a favourable or unfavourable cervix to help determine the method of IOL. The WHO recommends the use of betamimetics for women with uterine hyperstimulation in IOL. There is no advantage to adding amniotomy to IV oxytocin and amniotomy alone is not recommended for IOL [1].

3.2 NICE guidelines

Healthcare professionals must explain the following to women undergoing induction [7, 10]:

  1. Reasons for offering IOL
  2. When, where and how IOL will be performed
  3. Options for pain relief and support
  4. Risks and benefits of IOL
  5. Options for failed IOL or refusing IOL

NICE does not mention any contraindications to IOL; they do, however, mention when not to perform IOL such as in breech presentations, severe fetal growth restriction or maternal request. NICE recommends allowing women with uncomplicated pregnancies to undergo spontaneous labor before inducing them in post-term pregnancies. They consider vaginal PGE2, in the form of gel, tablet or controlled-release pess-ary, as the preferred method of induction (Table 4). Non-pharmacological methods such as herbal supple-ments, acupuncture, hot baths and sexual intercourse are not recommended as methods for IOL [7].

With regards to women with pre-existing medical conditions, NICE recommends particular guidelines pertaining to some diseases. For women with mech-anical heart valves, IOL or CS are indicated. When using low-molecular weight heparin (LMWH), aim to deliver as close as possible to 12 hours from the last injection. When using unfractionated heparin, deliv-ery is aimed as close to 4-6 hours after stopping the infusion. CS is indicated for women with any disease of the aorta, pulmonary arterial hypertension or New York Heart Association (NYHA) class III/IV heart disease. For women with chronic kidney disease, IOL is indicated before 40 weeks in those with stages 1-4 with stable renal function and between 34 and 38 weeks in those with stage 5 or deteriorating disease. Dialysis can be offered to help prolong pregnancy until 34 weeks at least. According to NICE, pros-taglandin F2 alpha should not be given to women with asthma due to the associated risk of bronch-ospasm. However, PGE1 or PGE2 can be used to induce women with asthma [10].

3.3 ACOG guidelines

When inducing a woman with IUFD, the method of IOL depends on the timing. If it occurs prior to 28 weeks of gestation then options include misoprostol, D&C or high-dose oxytocin infusion. If IUFD occurs after 28 weeks, then IOL according to the hospital’s policy is indicated. In patients with uterine hypers-timulation, CS or terbutaline are recommended if CTG demonstrates Category III tracing and one or more of the following: recurrent late or variable decelerations or bradycardia [2].

3.4 SOGC guidelines

SOGC does not consider amniotomy and oxytocin as effective methods of cervical ripening. Methods and indications of IOL do not change in the presence of GBS colonization. There are no recommendations on the use of laminaria tents but single or double balloon catheters can be used. Quality assurance programs can help to ensure that the indications for IOL are acceptable [4].

3.5 FOGSI guidelines

FOGSI recommends IOL at 39 weeks GA onwards in low-risk pregnancies. On the other hand, the timing of IOL differs depending on maternal conditions such as DM and hypertension. IOL for DM is indicated after 39 weeks if the condition is well-controlled on diet and at 38 weeks if managed on insulin or oral hypoglycemic agents (OHA). Women with uncont-rolled diabetes should be managed on a case-by-case basis. Those with hypertensive disorders can benefit from reduced complications and the need for antihypertensive therapy if induced. Induction is indicated before 37 weeks in PET and encouraged to continue beyond 37 weeks in gestational HTN [8]. FOGSI modifies the Bishop score by adding a point for PET and each previous vaginal delivery and sub-tracting a point for post-dates, nulliparity and PPROM. The Drug Controller General of India does not approve the use of misoprostol for inducing labor. FOGSI does not approve the use of laminaria tents, mifepristone, hyaluronidase or relaxin for IOL [8].

3.6 Queensland health guidelines

The Royal College of Obstetricians and Gynaeco-logists (RCOG) and Queensland Health recommends inducing labor in women 40 years and older at 39 to 40 weeks to help prevent late stillbirth [3, 9]. Maternal ethnicity is not an indication for IOL by itself, but it can guide the timing of induction. For instance, South Asian women are 2.4 times more likely than Australian women to develop stillbirth and twice as likely to have low birth weight. There is insufficient evidence regarding the use of laminaria tents, acupuncture, homeopathy, breast stimulation or sexual intercourse for inducing labor [3].

3.7 KHUH guidelines

Prior to inducing labor, the patient’s antenatal records must be reviewed and they need to be examined clinically. Baseline NST and cervical status must be documented before commencing IOL. The physician must explain the indications for undergoing IOL and the associated risks and benefits. IOL is indicated when the benefits of terminating the pregnancy outweigh the risks of continuing it. Such indications include post-term pregnancy, maternal medical con-ditions and fetal compromise. The contraindications to IOL are the same as those suggested by ACOG. Membrane sweeping can be offered to women during vaginal examination and massaging the cervix in vaginal fornices can be an alternative. Amniotomy is not recommended alone, so it is best when combined with oxytocin. Cord presentation and high head must be ruled out before attempting an ARM. Both mother and fetus must be monitored following an amniotomy and oxytocin can be initiated [5]. PGE2 is recom-mended for IOL for an unfavourable cervix while oxytocin is preferred in women with a favourable cervix. Patients might require repeat dose(s) of PGE2. When administering oxytocin, patients need to be closely monitored for uterine contractions and abnor-malities on CTG. KHUH does not mention any recommendations on the use of misoprostol, mife-pristone or mechanical methods for IOL. There are also no suggestions on how to manage patients who develop uterine hyperstimulation or uterine rupture during IOL [5].

4. Conclusion

Comparing international guidelines elucidates the areas of improvement that are essential in enhancing patient care during IOL at KHUH. Such areas include recommendations on the timing of IOL according to the indication, alternative methods of IOL and proposals on how to manage particular complications associated with IOL. The practice of IOL in KHUH must be monitored as well to ensure the practice in our institute is consistent with both locally and internationally set guidelines to provide the optimum care to patients. This must also be frequently audited to confirm that IOL was indicated for valid reasons.

Financial Disclosure

The authors received no funding to perform this study.

Declaration of Conflicts of Interest

The authors report no conflicts of interest.

References

  1. World Health Organization. WHO Recommendations: Induction of Labor at or Beyond Term (2018).
  2. ACOG Practice Bulletin No. 107: Induction of labor. Obstet Gynecol 114 (2009): 386-397.
  3. Queensland Health. Induction of labor. [Queensland]: Queensland Health (2017).
  4. Leduc D, Biringer A, Lee L, et al. Induction of labor. J Obstet Gynaecol Can 35 (2013): 840-857.
  5. KHUH Hospital Policy on Induction of Labor
  6. National Institute for Health and Care Excellence. Insertion of a double balloon catheter for induction of labor in pregnant women without previous caesarean section. NICE (2015).
  7. National Institute for Health and Care Excellence. Inducing labor. [Manchester]: NICE (2008).
  8. Indian College of Obstetricians and Gynaecologists, The Federation of Obstetric and Gynaecological Societies of India. Induction of labor: Good clinical practice recommendations. [Mumbai]: FOGSI-ICOG (2008).
  9. Royal College of Obstetricians and Gynaecologists. Induction of labor at term in older mothers. [London]: RCOG (2013).
  10. National Institute for Health and Care Excellence. Intrapartum care for women with existing medical conditions or obstetric complications and their babies. [London]: NICE (2019).

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