Induction, augmentation and trial of labor

Prepared by:

Nisha Ghimire

Isha Aryal

Aayushma Khadka

Induction of labor (IOL) means initiation of uterine contractions after the period of viability by any method (medical, surgical or combined) for the purpose of vaginal delivery.

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

Pre-eclampsia and eclampsia

Maternal medical complications like diabetes mellitus, chronic renal disease, cholestasis of pregnancy

Post-maturity

Abruptio placenta

Intrauterine growth restriction

Premature rupture of membrane

Fetus with a major congenital anomaly

Intrauterine death of fetus

Oligohydramnios, polyhydramnios

Unstable lie

Lesser degree of placenta previa

Rh-isoimmunization

Contracted pelvis

Cephalopelvic disproportion

Malpresentation

Previous caesarean section or hysterectomy

High risk pregnancy with fetal compromise

Heart disease

Pelvic tumor

Elderly primigravida with obstetric or

medical complications

Cord prolapse

Cervical carcinoma

any contraindication for vaginal delivery

Uteroplacental factors: unexplained vaginal

bleeding, vasaprevia, placenta previa

Maternal:

emotional fear, anxiety

uterine inertia: prolonged labor

intrapartum infection

violent labor: abruption placenta, uterine

rupture, cervical laceration

amniotic fluid embolism

postpartum hemorrhage

Increased operative interference

Increased morbidity

Fetal:

Hypoxia

Iatrogenic prematurity (wrong dates)

Prolapsed cord

infection

Induction of labor should be performed only when there is a clear medical indication for it and the expected benefits outweigh its potential harms.

In applying the recommendations, consideration must be given to the actual condition, wishes and preferences of each woman, with emphasis being placed

On cervical status, the specific method ofinduction of labor and associated conditionssuch as parity and rupture of membranes.

Induction of labor should be performed withcaution since the procedure carries the risk ofuterine hyper stimulation and rupture andfetal distress.

Wherever induction of labor is carried out,facilities should be available for assessingmaternal and fetal well-being.

Women receiving oxytocin, misoprostol or other prostaglandins should never be left unattended.

Failed induction of labor does not necessarily indicate caesarean section.

Wherever possible, induction of labor should be carried out in facilities where caesarean section can be performed.

Rating

Factor 0 1 2 3

Dilatation (cm) Closed 1-2 3-4 More than 5

Length of cervix (cm) More than 4 3-4 1-2 Less than 1

Consistency Firm Average Soft -

Position Posterior mid Anterior -

Descent by station of head

Descent by abdominal palpation

-3

4/5

-2

3/5

-1, 0

2/5

+1, +2

1/5

Medical: oxytocin, prostaglandin,

Surgical: Artificial Rupture of Membrane (ARM) Low rupture of Membrane (LRM) High Rupture of Membrane (HRM)

Stripping the membrane

Combined method

Prostaglandin:

Prostaglandin act on the cervix to enable ripening of cervix.

Prostaglandin E2 (PGE2) or cerviprime isinserted in the posterior fornix of vagina,usually in the form of 2-3 mg gel or 3mgpessary, every 6 to 8 hours as one, two orthree doses as required.

Misoprostol (PGE1) is being used either transvaginally or orally for IOL.

A dose of 25 mcg in the posterior fornix of the vagina or orally 50mcg is found as effective for cervical ripening and labor induction. It is administered about 6 to 8 doses as necessary.

Oxytocin:

Oxytocin causes contraction.

2.5 units of oxytocin usually mixed with 500ml of dextrose or normal saline is given intravenously.

Starting the infusion as 10 drops per minute, infusion rate is increased by 10 dpm every 30 min until a good contraction pattern is established, not exceeding 60 drops.

Medical

Surgical

Combined

MEDICAL INDUCTION

Drugs used:

Prostaglandins ( PGE2 , PGE1 )

Oxytocin

Mifepristone

Prostaglandins:

Prostaglandin act on cervixto enable ripening by a no. of differentmechanisms. PGE2 is primarily important forcervical ripening and myometrial contraction.

PGE2 (dinoprostone - 0.5mg ;6hrly 3-4 doses) increases the activity ofcollagenase and also sensitizes myometrium tooxytocin.

They cause increase in elastase,glycosaminoglycan , dermatan sulfate andhyaluronic acid levels in cervix causingrelaxation of cervical smooth muscle thatfacilitates dilatation.

Misoprostol (PGE1 ) used tansvaginallyor orally (25µg ; 4hrly) is found to be either superior or similarly effective to PGE2 for cervical ripening and labor induction.

Advantages:

Effective method in IUD or unfavourblecervix.

No anti-diuretic effect.

Highly effective in ripening the cervix during induction of labor.

Disadvantages :

Requires fetal monitoring for 1-2hrs

Risk for sustained contraction

Sometimes causes vaginal soreness

Nausea, vomiting or diarrhoea may be seen

Very occasionally cause uterine hyperstimulation affect FHR pattern

Uterine rupture may occur with Misoprostolthus is contraindicated in previous caeseriansection.

Oxytocin :

Oxytocin is an endogenous uterotonic that stimulates uterine contraction. Receptor concentration increases during pregnancy and labor. Oxytocin acts by :

a) Receptor mediation

b) Voltage-mediated calcium channels

c) Prostaglandin production

It is effective for induction of labor when cervix is ripe as it is less effective as ripening agent.

Advantages :

Wider availability

Less systemic effects

Major catastrophe is rare

Cheaper

Precautions:

Never give oxytocin IM before delivery

If FHR <100 bpm, stop the infusion

Assess contraction 1/2hrly if hyperstimulationoccurs

Water intocication with high or prolonged use

Rupture may occur in multigravida and previous c/s.

Mifepristone :( Progesterone receptor antagonists )

It blocks progesterone and corticosteroid receptors. 200mg vaginally daily for 2days has been found to ripen the cervix and to induce labor.

Progesterone inhibits contraction of the uterus, while mifepristone counteracts its action.

SURGICAL INDUCTION

Artificial rupture of membrane (ARM) Low rupture of membrane ( LRM)

High rupture of membrane (HRM)

Stripping of membranes

Artificial rupture of membrane (ARM )

Low rupture of membrane ( LRM):

It is a procedure where the puncture orrupture of the membrane below thepresenting part overlying the internal os todrain some amount of amniotic fluid.

Indications:

Abruptio placenta

Chronic hydraminos

Severe pre eclampsia/eclampsia

In combination with medical induction

To place electrode for fetal monitoring

Contraindications:

Intra uterine fetal death

Cephalo pelvic disproportion

Prematurity

Maternal AIDS or active genital herpes infection

Oblique or transverse lie

Contracted pelvis

Pelvic tumor

High rupture of membrane (HRM) :

It is the procedure in which puncture of the hind waters above the presenting part, is made by a special instrument named “drew smythe catheter”.

Indications :

obselete these days. However used inchronic hydraminos where regulated escapeof liquor amnii facilitates settling down ofpresenting part.

Contraindications:

Antepartum hemorrhage

Severe preeclampsia/eclampsia

Mechanism of onset of labor by ARM:

Stretching of cervix

Separation of the membranes

Reduction of amniotic fluid volume

Advantages of amniotomy:

a) High success rate

b) Chance to observe the amniotic fluid

c) Access to fetal scalp for electrode orscalp blood sampling.

Immediate beneficial effects of ARM:

Lowering of b.p in eclapsia; pre-eclampsia

Relief of maternal distress in hydraminos

Control of bleeding in APH

Relief of tension in abruptio placenta and

initiation of labor

Hazards of ARM:

Chance of cord prolapse

Amnionitis

Accidental injury

Amniotic fluid embolism

Stripping the membranes:

Stripping of the membrane means digitalseperation of the chorion and amnion from thewall of cervix and lower uterine segment.

Effective method in uncomplicated pregnancy.Prostaglandins are rapidly produced in theprocedure thus is used in cervical ripening aswell. It is safe simple and beneficial

Criteria for membrane stripping:

a) The fetal head must be well applied to the cervix

b) The cervix should be dilated so as to allow the introduction of examiner’s fingers

[ It is done prior to rupture of membrane as well ]

COMBINED METHOD

The combined medical and surgical methodsare used to increase the efficacy of induction byreducing the induction-delivery interval.

The oxytocin infusion is given either prior toor following rupture of membranes dependingmainly upon the state of the cervix and headbrim relation.

With non-engaged head, induction withprostaglandin or oxytocin followed by ARM ispreferable.

Advantage of combined methods:

More effective than any single procedure

Shortens the induction delivery interval

Minimizes the risk of infection

Lessens the period of observation

Stimulate the uterus during labour to increasethe frequency, duration and strength ofcontractions.

It involves stimulation of uterine contractionto produce delivery after the onset ofspontaneous labor.

It is officially indicated when SBA diagnoses“hypotonic uterine dysfunction” i.e.contractions ineffective at producing cervixdilatation.

Aims:

To expedite delivery within 12 hours without

increasing maternal mortality and pernatal

hazards.

Indications of augmentation:

Labor is prolonged without any evident cause.

Uterine contraction is ineffective and inefficient

To prevent risk of hypoxia from prolonged labor.

Contraindications of augmentation:

When labor is progressing normally

Woman isn't in true labor

Cephalopelvic disproportion

Mechanical obstruction (complete placenta

previa)

Abnormal presentation

Grand multipara

Previous uterine operation scar

Fetal distress

Cord prolapse and fetus is alive

Multiple gestation

Advantages of AMOL:

Less chance of dysfunctional labour

Shortens the duration of labor

Fetal hypoxia can be detected early

Low incidence of caeserian section.

Less analgesia

Less maternal anxiety.

Essential components of AMOL:

Antenatal education about purpose and

procedure of AMOL.

Woman is in true labor

Partographic monitoring of labor

Amniotomy with confirmation of labor

Oxytocin augmentation if cervical dilatation

(1cm/hr)

Delivery is completed within 12hrs of

admission .

Epidural anaesthesia is needed.

Fetal monitoring by intermittent auscultation

or by continous electronic monitoring

Active involvement of the consultation

obstetrician.

Definition :

It is a conduction of spontaneous labor in a moderate degree of cephalo -pelvic disproportion , in an institution under supervision with watchful expectancy ,hoping for vaginal delivery .

Aims:

Trial labor aims at avoiding an unnecessary cesarean section and delivering a healthy baby.

Associated mid pelvic and outlet contraction.

Presence of complicating factors like elderly primigravida , malpresentation , postmaturity , post cesarean section pregnancy ,pre –eclamsia , medical disorders like heart disease ,diabetes , tuberculosis , etc.

Where facilities of cesarean section are not available round the clock .

The management of trial labor requires careful supervision and consideration . The following guidelines are prescribed :

- the labor should ideally be spontaneous in onset . But in cases where labor fails to start even on due date , induction of labor may be done .

Oral feeding remains suspended and hydration is maintained by intravenous drip. Adequate analgesics is administered .pethidine 50 – 100 mg intramuscularly .

The progress of labor is mapped with partograph

To monitor the maternal health routine check up includes

(a)to record 2 hourly pulse , blood pressure and temperature .

(b)to observe the tongue periodically for hydration .

(c)To note the urine output , urine for acetone , glucose and

(d)IV fluids , drugs.

If there is failure to progress due to inadequate uterine contraction , augmentation of labor maybe done by amniotomy along with oxygen infusion . On no account should the procedure be employed before the cervix is at least 3cm .

After the membranous rupture , pelvic examination is to be done

(a) to exclude cord prolapse

(b) To note the color of liquor.

(c) To assess the pelvic once more

(d) To note the condition of cervix including pressure of presenting part on the cervix .

Degree of pelvic contraction

Shape of pelvis : flat pelvis is better than android or generally contracted pelvis

Favorable vertex presentation – anterior parietal presentation with less parietal obliquity is favorable

Intact membranes till full dilatations of cervix

Effective uterine contractions .

Emotional stability of women .

Appearance of abnormal uterine contraction

Cervical dilatation <1cm per hour (protacted active phase )inspite of regular uterine contractions

Arrest of cervical dilatation and non descent of fetal head inspite of oxytocin therapy

Early rupture of membranes

Formation of caput and evidence of excessive moulding

Fetal distress.

It is indeed difficult to set a arbitrary time limit which is applicable to all cases . One should be individualized the case .

So long the progress is satisfactory (evidence by descent of head and progressive cervical dilatation ) and maternal and fetal condition remain good ,trail may be continued safely .

However , if any ominous features appears ,trial is to be terminated forthwith .

Nowadays there is tendency to shorten the duration of trial .inspite of adequate uterine contractions , if there is arrest of uterine dilation of cervix for a reasonable period (3-4hrs ) in the active phase, labor is terminated by cesarean section

The methods are anyone of the following :

- spontaneous delivery :with or without episiotomy (30%)

- forceps or ventouse (30%) :difficult forceps delivery is to be avoided .

-cesarean section : judicious and timely decision foe cesarean delivery is to be taken . However ,is significant cases , the section is done even before full dilations of cervix , the indication being uterine inertia or fetal distress

A trial is successful ,if a healthy baby is born vaginally , spontaneously or by forceps or ventose with the mother in good condition . Delivery by cesarean section or delivery if dead baby ,spontaneously or by craniotomy is called failure of trial labor .

It eliminates unnecessary cesarean section electively decided upon .

It eliminates injudicious use of premature induction of labor with its antecedents hazards

A successful trial ensures the woman a good future obstetrics .

Test of disproportion remains unproven when cesarean delivery is done due to fetal distress or uterine dysfunction

Increased perinatal morbidity or mortality due to asphyxia or intracranial hemorraghage when the trial is prolonged and / or ends in difficulty delivery

increased maternal morbidity due to effects of prolonged labor and / or operative delivery.

Increased psychological morbidity when the trial ends with a traumatic vaginal delivery or in cesarean delivery .

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