CERVICAL RIPENINGAND LABOUR INDUCTIONFAHAD ZAKWAN

INDICATIONS FOR INDUCTION OF LABOUR

•Not absolute: consider mom & baby’s health, gestational age, cervix….

Ex indications: • chorioamnionitis, • fetal demise, • gestational HTN, • PROM, • post term• preeclampsia/eclampsia…

Fetal: •oligohydramnios, •severe IUGR, • Isoimmunization

Logistic reasons: •precipitous delivery, •distance to hospital, •psychosocial reasons

RISK OF INDUCTION OF LABOUR

•Nulliparous with unfavorable cervix:•2 fold increased risk of cesarean delivery•labor progression differs significantly

CERVICAL STATUS•Bishop score: an attempt to quantify how likely the

cervix is to respond to induction efforts

Bishop Score

What’s most important in score?

•Dilatation >effacement>station• Unfavorable: score <6

• Ripening agent indicated

• Favorable: score >8• Can induce

• Probability of vaginal delivery with spontaneous labor equals probability of vaginal delivery with IOL

Cervical Remodeling:What has to happen to get labor to start?

• Proteins associated with contractions are expressed:• actin-myosin interactions • myometrial cells excited• intercellular connectivity allowing synchronous contractions

• myofibrils transmit electrical activity to other myocytes• prostaglandins released & depolarize neighboring cells• leads to wave of activity, lasting 1 min• refractory period follows

Cervical Remodeling:What has to happen to get labor to start?

Fetal Membrane Activation

• Amnion produces:• Inflammatory mediators- cytokines

• Prostaglandin E2

• COX-2

Prostaglandins mediate release of metalloproteases• Weaken placental membranes

Cervical Remodeling:What has to happen to get labor to start?

Cervical Softening:

Inflammatory infiltrate moves into cervix

1. Release metalloproteases

degrade collagen – change cervical structure

2. Breakdown of junction between fetal membranes occurs

fetal fibronectin (adhesive protein) present in vaginal fluids

“Intravenous oxytocin alone for cervical ripening and induction of labor”

• Oxytocin is less effective than prostaglandin to help bring on labor but is as effective when used alone in women with ruptured membranes

• Oxytocin is the most common drug used to induce labor and has been used either alone or with rupturing the membranes.

• A review of trials found that using PGE2, inserted either via the vagina or cervix, rather than oxytocin was probably more effective.

• However, oxytocin alone compared to PGE2 used either way, in women with ruptured membranes, showed that all three methods are probably equally effective. More research is needed.

“Sexual intercourse for cervical ripening and induction of labor”

• The role of sexual intercourse as a method for induction of labor is uncertain.

•Human sperm contains a high amount of prostaglandin, a hormone-like substance which ripens the cervix and helps labor to start.

•nipple stimulation - >oxytocin

• lower uterine segment stimulated contractions occur w. orgasm

“Breast stimulation for cervical ripening and induction of labor”

• Breast stimulation appears beneficial in relation to the number of women not in labor after 72 hours, and reduced postpartum hemorrhage rates.

• Breast stimulation causes the womb to contract, though the mechanism remains unclear.

• It may increase levels of the hormone oxytocin, which stimulates contractions. It is a non-medical method allowing the woman greater control over the process of attempting to induce labor.

• The review found insufficient research to evaluate the safety of breast stimulation in a high-risk population and until safety issues have been fully evaluated.

“Castor oil, bath and/or enema for cervical priming and induction of labor”

• More research is needed into the effects of castor oil to induce labor.

• Castor oil has been widely used as a traditional method of inducing labor in midwifery practice. It can be taken by mouth or as an enema.

• The review of trials found there has not been enough research done to show the effects of castor oil on ripening the cervix or inducing labor or compare it to other methods of induction.

• The review found that all women who took castor oil by mouth felt nauseous. More research is needed “

• Evening primrose oil: unclear whether ripens or induces labor (also commonly used amongst midwives)

“Acupuncture for induction of labor”

• “There is insufficient evidence describing the efficacy of acupuncture to induce labor.

• Acupuncture is the insertion of fine needles into specific energy points of the body and has been used to help induce labor and reduce labor pains.

• The review included three trials involving 212 women. The evidence regarding the clinical effectiveness of this technique is limited, although small studies suggest women receiving acupuncture compared to standard obstetric care received fewer methods of induction.

Mechanical Options for Cervical Ripening

1. Foley: insert no 18 foley catheter w. 30 mL balloon past internal os, inflate balloon and place traction on catheter (tape to thigh)

• Outpatient or inpatient option• dilation>effacement>station

2. Laminaria: hydrophilic seaweed that absorbs water like sponge & slowly dilates cervix, doesn’t change consistency or effacement

3. Stripping membranes: commonly used & thought to be helpful in inducing labor. Freeing chorionic membrane from decidua of lower uterine segment • Increased PROM

“Amniotomy alone for induction of labor”

• There is not enough evidence about the effects of amniotomy alone (deliberate rupture of the membranes) to induce labor.

• Amniotomy has been used as either the only method of inducing labour if the membranes can be reached, or used with drugs such as oxytocin or prostaglandin.

• Amniotomy may be preferred by women wanting a drug-free labor and it is cheap.

• However, it can be uncomfortable and, if after amniotomy there is a long time interval before the baby is born, there is a risk of infection. There is also the risk of the cord coming out before the baby.

• This review of trials found that there is not enough evidence about the effects of amniotomy alone for the induction of labor “

Amniotomy

• helpful if labor stalls

• less effective with oligohydramnios

Considerations before amniotomy:

• FHR tracing before & after amniotomy

• Fetal head well applied?

• Palpate for cord? Vasa previa?

• HIV?

• Clock starts ticking…. ABX prophylaxis

“Induction of labor for improving birth outcomes for women at or beyond term”

• A policy of labor induction at 41 completed weeks or beyond was associated with fewer (all-cause) perinatal deaths

• There was no evidence of a statistically significant difference in the risk of caesarean section for women induced at 41 and 42 completed weeks respectively.

• Women induced at 37 to 40 completed weeks were more likely to have a caesarean section with expectant management than those in the labor induction group

• A policy of labor induction after 41 completed weeks or later compared to awaiting spontaneous labor either indefinitely or at least one week is associated with fewer perinatal deaths. However, the absolute risk is extremely small.

Cervical ripening, why?

Bishop score 6 or higher predicts successful induction and vaginal

delivery, if not at >=6, then cervical ripening indicated for achieving

dilation

Foley catheter:

• Foley catheter - balloon inflated past cervical os

• Foley catheter has been used to ripen cervix to inducible Bishop's scores,

• 97% effective in study of 88 patients with minimal complication

Vaginal misoprostol• In doses above 25 mcg four-hourly was more effective than

conventional methods of labor induction,

• More uterine hyperstimulation.

• The studies reviewed were not large enough to exclude the possibility of rare but serious adverse events,

• Rare uterine rupture has been reported anecdotally following misoprostol induction, in women with uterine scarring.

“Intracervical prostaglandins for induction of labor”

Prostaglandins inserted into the cervix are effective in starting labor, but are

inferior to vaginal administration.

Ripening Agents(Bishop < 8)

Options:1. Dinoprostone (PGE2)

– Gel or insert

2. Misoprostol (PGE1)3. Mechanical options

– Foley bulb

– Laminaria

– Membrane stripping

4. Alternatives

Labor InductionOxytocin: low & high dose regimens safe

•Preferred for IOL when cervix favorable

Low: less tachysystole w. concerning FHR

High: shorter labor, less chorioamnionitis, less C-section for dystocia but more tachysystole/concerning FHR

• Numeric value not established for max pitocin dose• Continuous monitoring necessary

Pitocin Induction

Management of complications associated with oxytocin

Uterine tachysystole & FHR with persistent decels, minimal-absent variability, fetal tachycardia….

• Stop or decrease pitocin

• Change position: side lying or hands-knees

• Oxygen

• IVF bolus

• Terbutaline sc

Labor Induction

Nipple stimulation: release oxytocin

PROM at term:

• Expectant Management: higher rates of chorio & less need for neonatal ABX treatment

• No difference in oxytocin vs PGE2: with IOL, no increase in c section rates (ACOG)

• Misoprostol 25 mcg q 6 hrs x 2 doses vs pitocin: delivery time shown to be the same (Wing 2006)