Induction of Labor

Amr Nadim, MDProfessor of Obstetrics & Gynecology

Ain Shams Faculty of Medicine[prof.amrnadim@gmail.com]

Nice to Know

Likely to know

Core

Should Know

What you MUST know about this topic

• List the different indications for induction of labor.

• Describe the different techniques of induction of labor.

• Recognize favorability for induction of labor with special emphasis on Bishop’s score.

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

Labor

• The process of uterine contractions leading to progressive effacement and dilatation of the cervix and birth of the baby. – Spontaneous onset of labor– Induction of labor– Augmentation of Labor

Induction of labor• An intervention designed to artificially initiate

uterine contractions leading to progressive dilatation and effacement of the cervix and birth of the baby.

• This includes both women with intact membranes and women with spontaneous rupture of the membranes but who are not in labor.

• The term is usually restricted to pregnancies at gestations greater than the legal definition of

fetal viability

Augmentation

• An intervention designed to increase the rate of progress of labor

Uterine hypercontractility• Uterine tachysystole (more than five

contractions per ten minutes for at least 20 minutes) + + uterine hypersystole / hypertonus (a contraction lasting at least two minutes).

• Uterine hyperstimulation with FHR changes denoted uterine hyperstimulation syndrome (tachysystole or hypersystole with FHR changes such as persistent decelerations, tachycardia or decreased short term variability).

When you think about inducing labor…

• This means that you will terminate the

pregnancy while considering the vaginal

route as the MOST LIKELY possible way

of delivery.

• TOP may be thought of and be conducted

by Cesarean Section if vaginal delivery is

thought NOT FEASIBLE.

When to Induce?When to Induce?

Induction is indicated when the benefits to

either the mother or fetus outweigh those of

continuing the pregnancy.

When to Induce?When to Induce?

• Maternal medical problems– Hypertension– Diabetes Mellitus– Renal disorders

• Social factors ???– The Mother – Or the Doctor

.

When to Induce• Obstetric complications:

• PROM.

• Post term pregnancy.

• Fetal Problems:

• Fetal demise.

• Suspected fetal jeopardy.

• I.U.G.RWill probably be

indications for CS

Contraindications

• Maternal conditions– Abnormal Pelvic capacity– Medical conditions.– Previous scarred uterus

• Fetal conditions• Macrosomia• Hydrocephalus• Malpresentations

Where to induce

• Antenatal ward

• Labor / Delivery Suite

Fetal Consideration

• Adequate estimation of the gestational age is of UTMOST importance.

• Wherever induction of labor occurs, facilities should be available for continuous uterine and FHR monitoring.

Cervical favorability

• A favorable cervix is defined as one with a modified Bishop’s score of greater than eight.• A score less than 4 is describing an Unfavorable Cervix• A trade off between favorable / Unfavorable is a 4 < score < 8

The Original Bishop’s Score

An unfavorable cervix will need 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.

I-Natural-Non Medical methods (Cont.)

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

I-Natural-Non Medical methods (Cont.)

8-8-Cumin TeaCumin 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 methods

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.)

1-Hygroscopic dilators: 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.

II-Mechanical methods (Cont.)

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: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.

II-II-Mechanical methods Mechanical methods (Cont.)(Cont.)

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 Methods

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)

III-Surgical Methods (Cont.)

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 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-III-Surgical MethodsSurgical Methods (Cont.) (Cont.)

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

IV-IV-Pharmacologic Induction of LaborPharmacologic 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.

IV-Pharmacologic Induction of Labor (Cont.)

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.

IV-IV-Pharmacologic Induction of LaborPharmacologic Induction of Labor

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%

IV-IV-Pharmacologic Induction of Labor Pharmacologic Induction of Labor (Cont.)(Cont.)

2-Misoprostol:

- Clinical trials indicate that the safe optimal dose and dosing interval is 25 mcg intravaginally 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).

IV-Pharmacologic Induction of Labor (Cont.)

- 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).

IV-Pharmacologic Induction of Labor (Cont.)

3-Mifepristone:• Mifepristone (Mifeprex) 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 is scarse and cannot be used to recommend the use of mifepristone for cervical ripening.

IV-IV-Pharmacologic Induction of Labor Pharmacologic Induction of Labor (Cont.)(Cont.)

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.

IV-IV-Pharmacologic Induction of Labor Pharmacologic Induction of Labor (Cont.)(Cont.)Oxytocin ProtocolOxytocin Protocol

-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.

IV-Pharmacologic Induction of Labor (Cont.)

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 Hyperbiliribinemia

PG E2

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.

When undertaking induction of labor in women, with recognized risk factors (e.g. including suspected fetal growth compromise, previous caesarean section and high parity)

• The clinical discussion regarding the timing and method of induction of labor should be undertaken at consultant level.

• The induction process should not occur on an antenatal ward