Induction of Labor التحريض على الولادة

Induction of Laborالوالدة التحريضعلى

Amr Nadim, MDProfessor of Obstetrics & Gynecology

Ain Shams Maternity & Women’s Hospital

By the end of this session, you should be able to:

• Define induction of labor and make the difference between induction

and augmentation of labor.

• Understand the prerequisites for induction of labor

• Enumerate the indications and contraindications of induction of labor.

• Recognize favorability for induction of labor with special emphasis on

Bishop’s score.

• Discuss the different methods of induction of labor.

• List the complications of induction of labor and drugs used in it.

By definition…

• Is the planned initiation of labor prior to the

onset of spontaneous labor.

• It is an obstetric intervention that should be

used when elective birth is beneficial to

mother and baby.

Augmentation of Labor…

• This is the intervention by which labor is accelerated– Labor started spontaneously– The progress is unsatisfactory due to a defect in

the uterine contractions – Oxytocin is given to correct for such defect

Induction of Labor

• Incidence of about 20%

• In the UK , among women subjected to

induction of labor:

– 63% delivered by a spontaneous VD

– 15% delivered by an operative vaginal delivery

– 22% delivered by emergency CS

• Induction of labor can place more strain on

– Labor ward personnel and the obstetrician

– The lady and her family than spontaneous labor

• It has a large impact on the health of women

and their babies and so needs to be clearly

clinically justified.

Prerequisites

• Discussion of the issue with the mother

• Evaluation of the mother and the fetus

Discussion of the issue…• Discussion of the whole issue with the mother– The reasons for induction being offered – When, where and how induction could be carried out – The arrangements for support and pain relief

(recognizing that women are likely to find induced labor more painful than spontaneous labor)

– The alternative options if the woman chooses not to have induction of labor

– The risks and benefits of induction of labor in specific circumstances and the proposed induction methods

– That induction may not be successful and what the woman’s options would be.

Discussion of the issue…• Healthcare professionals offering induction of

labor should: – allow the woman time to discuss the information

with her partner before coming to a decision – encourage the woman to look at a variety of

sources of information – invite the woman to ask questions, and encourage

her to think about her options – support the woman in whatever decision she

makes.

Assessment of the Lady• Verification of the Gestational Age– What is meant by reliable Dates?

Excellent Dates• Adequate Clinical Information+ US confirmation [early or 16-24]• Inadequate or incomplete Clinical information but 2 US [16-24] showing

linear fetal growth and similar EDD

Good Dates• Adequate Clinical Information+ US confirmation [afte24 weeks]• Inadequate clinical Information + 2 US

Poor Dates• Any other Situation

• May God help us

Assessment for the Predictability of the Success of Induction: The Bishop’s Score

Scoring

Cervix 0 1 2 3

•Position Post Mid posterior Anterior

•Consistency Firm Medium Soft

•Effacement 0-30%[

40-50% 60-70% > 80%

•Dilatation Closed 1-2 cm. 3-4 cm. > 5 cm.

Head Station -3 -2 -1 +1, +2

• A score of 5 or less suggests that labor is unlikely to start without induction.• A score of 9 or more indicates that labor will most likely commence spontaneously.• A low Bishop's score often indicates that induction is unlikely to be successful• A score of 8 or greater is reliably predictive of a successful induction.

Modified Bishop’s Score• According to the Modified Bishop's pre-induction cervical

scoring system, effacement has been replaced by cervical length in cm, with scores as follows 0: 3cm – 1: 2cm – 2: 1cm – 3: 0cm.

• Another modification for the Bishop's score is the modifiers. – Points are added or subtracted according to special circumstances

as follows: • One point is added for

– 1. Existence of pre-eclampsia – 2. Every previous vaginal delivery

• One point is subtracted for – 1. Postdate pregnancy– 2. Nulliparity – 3. PPROM

Indications

Maternal• Prolongation of pregnancy• P.I.H • Medical conditions (as renal,

respiratory and cardiac diseases, Diabetes Mellitus)

• Placental insufficiency• Prolonged pre-labor rupture

of membranes.• Rhesus iso-immunization.• ?? Previous precipitate Labor• ??Maternal request.

Fetal• Prior IUFD at a later

gestational age• Suspected IUGR

– Severe IUGR is a contraindication• ?? Suspected Macrosomia• IUFD

Whenever the presence of the fetus in utero is jeopardizing the mother or the fetus:

Prevention of prolonged pregnancy• Women with uncomplicated pregnancies should be given every opportunity

to go into spontaneous labor.

• Women with uncomplicated pregnancies should usually be offered induction

of labor between 41+0 and 42+0 weeks to avoid the risks of prolonged

pregnancy. The exact timing should take into account the woman’s preferences

and local circumstances.

– If a woman chooses not to have induction of labor, her decision should be respected.

– From 42 weeks,

• women who decline induction of labor should be offered increased antenatal monitoring

consisting of at least twice-weekly cardiotocography and ultrasound estimation of maximum

amniotic pool depth.

Rupture Of Membranes

Preterm Prelabor ROM• Induction of labor should not be

carried out before 34 weeks unless there are additional obstetric indications (for example, infection or fetal compromise).

• After 34 weeks, following factors should be taken into consideration:– risks to the woman (for example,

sepsis, possible need for caesarean section)

– risks to the baby (for example, sepsis, problems relating to preterm birth)

– Availability of NICU

Term Prelabor ROM• Should be offered a choice

of induction of labor• Induction of labor is

appropriate approximately 24 hours after prelabor rupture of the membranes at term.

Previous Cesarean Section• If delivery is indicated, women who have had a

previous caesarean section may be offered– induction of labor, – cesarean section or – expectant management on an individual basis, taking into

account the woman’s circumstances and wishes. • Women should be informed of the following risks with

induction of labor: – increased risk of need for emergency caesarean section

during induced labor – increased risk of uterine rupture.

Methods of Induction of Labor

Pre-induction Cervical Ripening

Bringing About Uterine

Contractions

•Natural methods•Mechanical Methods

•Surgical Methods•Pharmacologic

Methods

Pre-induction Cervical Ripening

I-Natural-Non Medical methods

1-Relaxation techniques: advise patient to relieve tension and try to relax then use some visual aids to show how labor starts.

2-Visualization: The patient is advised to imagine her uterus contracting and she is laboring. Hypnosis/self-hypnosis helps.

3-Walking: The force of gravity pulls the weight of the baby towards the birth canal leading to dilatation and effacement of the cervix.

I-Natural-Non Medical methods (Cont.)

4-Sex: Having sex is known to induce labor. This is related to prostaglandin content of the seminal fluid and the occurrence of orgasm which stimulate uterine contractions

5-Nipple stimulation: The lady moves her palm and applies some pressure in a circular fashion over her areola and massaging nipple between thumb and forefingers for a period of 2 minutes alternating with 3 minutes of rest. The procedure is performed for 20 minutes. If adequate contraction pattern is not achieved, massaging was done for 3 minutes alternating with 2 minutes rest for additional 20 minutes. Care should be taken to avoid massaging during a contraction and to only massage one side at a time in order to avoid hyperstimulation.


6-Bath/Castor oil/Enemas: The patient is advised to take a warm bath then to have 3 teaspoons of castor oil mixed with some juice and an enema thereafter. This method could stimulate the uterus to contract, which will cause the cervix to dilate and efface.

7-Foods: Eating lots of pineapple is known to stimulate labor and ripen the cervix. This is possibly related to its enzyme content. Other foods with similar action include Pizza, spicy food like Mexican, and tropical fruits


8-Cumin Tea: Used by midwives in Latino cultures. Sugar or honey may be added to lessen its bitter taste

9-Several herbs: Labor-enhancing herbs include blue Cohosh, black Cohosh, Squawvine and Dong Quai. Evening primrose oil also ripens the cervix. It is given internally 5 gel caps up against the cervix daily.

10-Acupressure:

Few health personnel claim an association between some acupressure points in the body and increased uterine contractions. One point is located deep in the webbing between thumb and forefinger. Massaging this point in a circular motion for 1-5 minutes stimulates labor pain and induce labor.

II- Mechanical methodsHygroscopic Dilators – Balloon Dilatation

1-Hygroscopic dilators

They absorb endocervical and local tissue fluids, causing the device to expand within the endocervix and provide mechanical pressure. These dilators are either natural osmotic dilators (e.g., Laminaria japonicum) or synthetic osmotic dilators (e.g., Lamicel).

Advantages: 1- Outpatient placement 2- No need for fetal monitoring

Risks: fetal and/or maternal infection

II- Mechanical methods (Cont.)

Technique of insertion:

-The perineum and vagina are sterilized with betadine & the patient is drapped.

-Using a sterile speculum, the dilator is introduced into the endocervix.

-Dilators are progressively placed until the endocervix is full.

-A sterile gauze pad is placed in the vagina to maintain the position of the dilators.


2- Placement of Balloon Dilators after 42 weeks gestation:

A fluid filled balloon is inserted inside the cervix. The Balloon provide mechanical pressure directly on the cervix which respond by ripening and dilation. A Foley catheter (26 Fr) or specifically designed balloon devices can be used.

Technique of balloon placement:

1- After sterilization and draping, the catheter is introduced into the endocervix either by direct visualization or blindly by sliding it over fingers through the endocervix into the potential space between the amniotic membrane & the lower uterine segment.

2- The balloon is inflated with 30 to 50 mL of normal saline and is retracted so that it rests on the internal os.

3- Constant pressure may be applied over the catheter. e.g. a bag filled with 1 L of fluid may be attached to the catheter end. An intermittent pressure may also be exerted on the catheter end 2 -4 times per hour.

4-Catheter is removed at the time of rupture of membranes or may be expelled spontaneously which indicate a cervical dilatation of 3-4 Centimeter.


III- Surgical MethodsStripping of the membranes - Amniotomy

1-Stripping the membranes:- Stripping the membranes mechanically dilates the cervix which releases

prostaglandins. The membranes are stripped by inserting the examining finger through the internal os & moving it in a circular direction to detach the inferior pole of the membranes from the lower uterine segment.

- Risks include patient’s discomfort, infection, bleeding from undiagnosed placenta previa or low lying placenta,and accidental ROM.

- The Cochrane reviewers concluded that stripping the membranes, when used as an adjunct, decreases the mean dose of oxytocin needed and increases the rate of normal vaginal deliveries.

( Evidence level A)

2-Amniotomy - Technique:

-The FHR is recorded before the procedure.

-A pelvic examination is performed to evaluate the cervix & station of the presenting part. The presenting part should be well fitted to the cervix.

-The membranes are identified and an amnihook ( or a Kocher) is inserted through the cervical os by sliding it along the hand & fingers & membranes are ruptured.

-The nature of the amniotic fluid is recorded (clear, bloody, thick or thin, meconium).

-The FHR is recorded after the procedure.

III- Surgical Methods

Risks of amniotomy:

1- Prolapse of the umbilical cord (0.5%)

2- Chorioamnionitis: Risk increases with prolonged induction delivery interval

3- Postpartum hemorrhage: Risk is doubled compared with women with spontaneous onset of labor

4- Rupture of vasa previa

III- Surgical Methods

IV-Pharmacologic Induction of Labor

1-Prostaglandin E2: (dinoprostone):

• It is inserted vaginally as a gel (Prepidil), as a removable tampon (Cervidil) or as a vaginal pessary.

• It acts on the cervical connective tissue and relaxes muscle fibres of the cervix.

• Dinoprostone should only be administered at hospital and the patient is expected to stay recumbent and monitored, at least, for the first 30 minutes after insertion.

• Contractions usually start within 60 minutes of commencing induction and peak within 4 hours. If optimal response is not achieved by 6 hours, another dose can be administered.

• The maximum allowed dose is 3 doses be administered per 24 hours.

Cervidil contains 10 mg of dinoprostone and provides a lower constant release of medication (0.3 mg per hour) than Prepidil does. Cervidil have the advantage of being removed more easily if uterine hyperstimulation occurs. In addition, it does not require refrigeration.

• PGE2 can cause uterine hyperstimulation, fetal distress and Cesarean section.



2- Misoprostol:-Misoprostol (Cytotec®) is a synthetic PGE1 analog that has been found to be a

safe and inexpensive agent for cervical ripening.

Pharmacokinetics:• Route of administration: Oral, vaginal and sublingual route for induction.

Rectal route is used to prevent and treat postpartum hemorrhage.• Bioavailability: Extensively absorbed from the GIT• Metabolism: De-esterified to prostaglandin F analogs• Half life: 20–40 minutes• Excretion: Mainly renal 80%, remainder is fecal: 15%


- Clinical trials indicate that the safe optimal dose and dosing interval is 25 mcg intravaginally (Vagiprost® ) every 4-6 hours.

- A maximum of 6 doses was suggested. - Higher doses or shorter dosing intervals are associated with a

higher incidence of side effects, especially hyperstimulation syndrome.

-Misoprostol should not be used in women with previous CS because of increased rates of uterine rupture (Evidence level B).


- The Cochrane reviewers concluded that use of misoprostol resulted in an overall lower incidence of CS.

- In addition, there appears to be a higher incidence of vaginal delivery within 24 hours of application and a reduced need for oxytocin augmentation.

(Evidence level A).


3-Mifepristone:

• Is an antiprogesterone agent which counteracts the inhibitory effect of Progesterone on the uterus.

• Few studies with small number of women enrolled, have shown that women treated with mifepristone in a dose of 600 mg are more likely to have a favorable cervix and deliver within 48 to 96 hrs when compared with placebo and also they these were less likely to undergo C.S.

• Information about fetal outcomes & maternal side effects are scarse and cannot be used to recommend the use of mifepristone for cervical ripening.


4- Oxytocin:

It is given by IV infusion using an automated pump. Oxytocin has many advantages: it is potent and easy to titrate, has a short half-life (one to five minutes) and is well tolerated.


Oxytocin Regimen:ASU Maternity Hospital regimen

• Oxytocin infusion should be given in the smallest possible volume, commencing at a rate of 1 mU/min

• Usually start by 5 units in 500mls of normal saline or Ringer’s solution [10 mU/ml]

• Increase infusion rate (by doubling drops / min) at intervals of 30 min, until there are 3-5 good contractions every 10 min each lasting 45-60 sec. [1 ml=15-drops]

• If 60 drop/min rate is reached with no efficient contractions replace the infusion with 10 units oxytocin in 500 mls

• Total dose of oxytocin should not exceed 5 units.

Let’s do some calculations…

• 500 ml 1ml = 1/100 U = 10 / 1000U =10 m U/ml• 1 ml = 15 drops :.each 15 drops contains 10

mIU and each 30 drops contains…..

5 units? = 5/500 U

-If infusion volumes were found to be excessive, prepare double

strength solution.

-If no progress occurred after 8–12 hours of starting induction, either

discontinue the oxytocin and reapply a cervical ripening agent or re-

initiate oxytocin the next day.


Side effects of oxytocin use: 1-Uterine hyperstimulation and subsequent FHR abnormalities.

2-Abruptio placentae and uterine rupture.

3-Water intoxication may occur with high concentrations of oxytocin infused with large quantities of hypotonic solutions. Therefore; prolonged administration with doses higher than 40 mu of oxytocin per minute and infusion of fluids in any 10 hours should not excced 1500 ml. A rapid intravenous injection of oxytocin may cause hypotension.

4- Neonatal Hyperbilirubinemia


Complications for Induction of Labor

• Maternal– Emotional: fear, anxiety– Uterine inertia .. prolonged labor– Intrapartum infection– Violent labor: abruptio placentae; uterine rupture; cervical

laceration– Increased CS rate– Amniotic fluid embolism– Postpartum hemorrhage– Complications of the method used for induction

Complications for Induction of Labor

• Fetal– Hypoxia– Iatrogenic prematurity [wrong dates]– Prolapsed cord– Infection [frequent vaginal examination]

Non-reassuring FHR patterns • The oxytocin infusion should be decreased or

discontinued.• Tocolysis should be considered. [Subcutaneous

terbutaline 0.25 milligrams].• In cases of suspected or confirmed acute fetal

compromise, delivery should be accomplished as soon as possible, ideally, this should be accomplished within 30 minutes.

Here are things that are Nice 4 U to know….

IUGR

• There are insufficient data to comment on the risks of induction of labor of women with babies with known growth restriction.

• In one study perinatal mortality was nearly five times that of normal weight infants.

• Infants with IUGR enter labor in an increased state of vulnerability and are more likely to become acidotic because of:• uteroplacental insufficiency• lower metabolic reserves due to intrauterine malnutrition or pre-

existing hypoxia• an umbilical cord more prone to compression due to a reduction in

amniotic fluid volume.

Previous CS or scarred uterus

• Induction of labor with a history of a previous caesarean section is not contraindicated but careful consideration of the mother’s clinical condition should be taken before induction is started.

• A uterus with a fundal Myomectomy or a vertical upper segment scar is a contraindication for VBAC and hence for IOL

Induction of labor in attempted VBAC

• Spontaneous labor is most successful & has lowest rate of uterine rupture

• Misoprostol should never be used • Rates of rupture differed by method of induction:• Spontaneous labor - 0.52%• Induction without prostaglandins - 0.72%• Induction with prostaglandins – 2.45%

Breech

• There is an increased risk associated with planned vaginal breech delivery. The risks associated with induction of labor with a breech presentation cannot be quantified from the available trial literature.

• There is a place for IOL after external cephalic version of a breech

• Induction of labor in women of high parity may be associated with an increased incidence of precipitate labor, uterine rupture and postpartum hemorrhage.

• Induction of labor in women of high parity with standard oxytocin regimens may be associated with an increase in uterine rupture.

Failed induction...?• What constitutes a failed induction?• If induction fails, healthcare professionals should

discuss this with the woman and provide support. – The woman’s condition and the pregnancy in general

should be fully reassessed, and fetal wellbeing should be assessed using electronic fetal monitoring.

• The subsequent management options include: – a further attempt to induce labour (the timing should

depend on the clinical situation and the woman’s wishes)

– Cesarean section

Induction of Labor التحريض على الولادة

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