Labor induction Dr. shakeri

Amir hospital

Labor inductionDefinition -induction -augmentation35% of labors are induced or augmentedIndicated when the benefits to either mother

or fetus outweight those of continuing the pregnancy

Indications Ruptured membranes with chorioamnionitisSevere preeclampsiaMembrane rupture without laborGestational hypertensionNonreassuring fetal statusPostterm pregnancyMaternal medical condition such as chronic

H.T and diabetes

ContraindicationsFetal factors(appreciable macrosomia,

multifetal gestation, severe hydrocephalus, malpresentation, nonreassuring fetal status

Maternal factors(prior incision type, contracted pelvic anatomy, abnormal placentation, active genital herpes infection and cervical cancer

Risks Matenal complication rates that are increased with

induction -chorioamnionitis -uterine atony -C/S . especially increased in NP X2-3 . in nulliparas >41w with unengaged vertex the

risk increases 12-fold .No increased risk if the engaged fetal head is OP

Cervical favorabilityOne method used to predict outcome of

induction is the score described by BishopBishop score of 9 conveys a high

likelihood for a successful inductionIn unfavorable cervix -methods use for cervical ripening

include . pharmacological techniques(PGE1-

PGE2) . mechanical techniques

Bishop scoreScore Dilate Eff Station C.Consiste

ncyc.position

0 closed 0-30% -3 firm post

1 1-2cm 40-50% -2 medium mid

2 3-4cm 60-70% -1,0 soft ant

3 ≥5cm ≥80% +1,+2 - -

Prostaglandin E2(Dinoprostone)Its gel form-Prepidil-is available in a 2.5 ml syringe

for application of 0.5 mg of dinoprostone -the gel is deposite just the internal cervical os -after application she remains declined for 30 min - doses may be repeated every 6 h -maximum three doses in 24 hVaginal insert form( 10mg)-Cervidil-placed in

posterior vaginal cervix(slower release of medication-0.3mg/h)

-following insertion she should remain recumbent for at least 2h/the insert is removed after 12h or with labor onset

AdministrationIn or near the delivery suiteUterine activity and FHR monitoring should

be performed contraction begins in first hour and show

peak activity in the first 4hOxytocin induction should be delayed for 6

to12 hours following PG administration

Side effectsUterine tachysystole in 1 to 5%Uterine tachysystol is defined as≥6

contractions in a 10 minute periodUterine hypertonus is defined as a single

contraction lasting longer than 2 minutesUterine hyperstimulation is when either

condition leads a nonreassuring FHR pattern

In preexisting spontaneous labor, PG used is not recommended

If hyperstimulation occurs with the 10-mg insert, its removed by pulling on the tail of the surrounding net sac will usually reverse this effect

Irrigation to remove the gel has not been helpful

CIAsthma, glucoma, increased intraocular

pressureRecommendation caution aganis its use in

PROM

Prostaglandin E1 (Cytotec)Approved as a100 or 200µg tablet for prevention of

peptic ulcersMay be administered orally or vaginally100µg oral dose was as effective as 25µg intravaginal

doseTablets are stable at room temperatureIs the PG of choice at both Parkland and Birmingham

HospitalThe ACOG recommended the 25µg dose(a fourth of a

100µgtablets)In prior uterine surgery, including C/S ,the use of

cytotec is contraindicated

Nitric oxide donorsIsosorbide mononitrate did not enhance

cervical ripening either in early pregnancy or at term

Did not shorten time to vaginal delivery

Mechanical techniques1-Transvaginal catheter -80ml Foley transcervical catheter balloon

was significantly more effective than 30ml Foley

-did not increase the risk of PTL in the next pregnancy

2-Extra amnionic saline infusion(EASI) -room temperature normal saline is infused

through the catheter of foley ( 30-40 ml/h )

3-Hygroscopic cervical dilators -ascending infection have not been verified -their used to be safe -anaphylaxis has followed laminaria insertion -are attractive because of their low cost and

easy placement and removed -longer induction to delivery time compared

with EASI4-Membrane stripping for labor induction -two thirds of stripping group entered

spontaneous labor within 72h

oxytocinIs one of the most commonly used medication

in USAThe first polypeptide hormone synthesizedAn achievement for which the 1955 Nobel

Prize in chemistry was awardedWith oxytocin use, ACOG recommended FHR

and contraction monitoring similar to any high risk pregnancy

IV oxytocin administrstionThe goal is to effective uterine activity sufficient to

produce cervical change and fetal descent, while avoiding development of nonreassuring fetal status

Oxytocin should be discontinued if -the number of contractions greater than5 in a 10

min -seven in a 15 min period -persistant nonreassuring FHR pattern Discontinuation of oxytocin rapidly decreases the frequency of contractionsMean half-life is 5 minutes

Response is highly variable and depends on preexisting uterin activity, cervical status, pregnancy duration and biological differences

Uterine response increases from 20 to 30 weeks and increases rapidly at term

A 1-ml ampule containing 10 units usually is dilutaed into 1000ml of a crystalloid solution and administered by infusion pump

The Parkland Hospital protocol: -starting dose of oxytocin at 6 mU , with 6-

mU/min increases every 40 min, but employs flexible dosing on hyperstimulation

The Birmingham Hospital protocol : -begins oxytocin at 2mU/min and increases it

as needed every 15 minutes to 4, 8, 12, 16, 20,

25, 30 m/min

Side effectHas amino-acid homology similar to

vasopressinHas significant antidiuretic actionWhen infused at doses of 20mU/min or more,

renal free water clearance decreases marketly

Water intoxication can lead to convultion, coma and even death

If oxytocin is to be administered in high doses, its concentration should be increased rather than increasing the flow rate of dilute solution

Amniotomy A common indication for artificial rupture of

membranes includes the need for direct monitoring of the FHR or uterine contractions

Care should be taken to avoid disloding the fetal head, to minimize the risk of cord prolapse

Fundal or suprapubic pressure may reduce the risk

Some clinicians prefer to rupture membranes during a contraction

FHR should be assessed before and immediately after amniotomy

Early amniotomy at 1 to 2 cm - associated with significant 4-hour shorter

labor -increased incidence of chorioamnionitis Late amniotomy at 5 cm -accelerated spontaneous labor by 1 to 2

hours -C/S was not increased -no adverse perinatal effects -increased mild to moderate cord

compression pattern

Amniotomy augmentation -perform amniotomy when labor is

abnormally slow -significantly increases the incidence of chorioamnionitis