1 Preterm Labor

7/23/2019 1 Preterm Labor

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Preterm Labor

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Preterm Labor


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Objectives

Definition and Incidence

Etiology

Diagnosis Management

- Delaying delivery

- Promoting fetal maturity

- When to transfer

- Delivery


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Definition

regular uterine contractions accompanied by

progressive cervical dilatation and/oreffacement at less than 37 weeks gestation


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Diagnosis

establish dates

history of contractions, risk factors

abdominal exam for uterine activity cervical exam - serial if reasonable

sterile speculum exam alone should be done in PPROM

defer digital exam if there is undiagnosed vaginalbleeding until _______ of placenta is known


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Establishing the EDD - LMP

Naegele's Rule can be used in conjunction with the

LMP if:

- first day of last menses is known- period was 'normal'

- cycle is regular and between 24 and 35 days

- no recent hormonal contraception, lactation or

pregnancy (3 subsequent spontaneous periods)


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Establishing the EDD - When ultrasound is

available

Ultrasound should be used when the LMP is unknown

or criteria are not fulfilled for its use in calculating the

EDD U/S dating accuracy decreases as gestational age

increases

- 7 - 12 weeks GA 5 days

- 13 - 20 weeks GA 1 week- 21 - 30 weeks GA 2 weeks

- > 30 weeks GA 3 weeks


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Establishing the EDD

please tell someone the EDD!

- inform woman of EDD from LMP if appropriate and

reinforce at time of dating and/or 18 week

ultrasound- document EDD on antenatal forms

- document dates and findings of each ultrasound on

antenatal (include placental location)

good dating is useless if no one but you knows the

EDD and you are not available


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Incidence

preterm delivery occurs in about 7% of pregnancies

there has been little change in this rate despite newtechnologies


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Significance

preterm birth accounts for 75% of perinatal mortality

significant longterm neonatal/pediatric sequelae

- CNS and neurodevelopmental

- respiratory

- blindness and deafness


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Etiology

Idiopathic

Antepartum haemorrhage

Preterm prelabor rupture of membranes

Chorioamnionitis

Multiple pregnancy / Polyhydramnios

Incompetent cervix / Uterine Anomaly

Maternal disease Fetal anomaly


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Prevention

Effective intervensions

- screening and treating for asymptomatic bacteriuria

- screening and treating for BV in women who have had

a prior preterm birth

Ineffective intervensions

- risk scoring

- bedrest

- avoiding coitus

- home uterine monitoring


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Predictors

New initiatives and technplogies

- fetal fibronectin

- endovaginal cervical sonography


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Outcome

Sensitivity specificity

Delivery


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Shortening of the cervix
http://content.nejm.org/content/vol334/issue9/images/large/04t1.jpeghttp://content.nejm.org/content/vol334/issue9/images/large/04t1.jpeg


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V shaped cervical dilatation

33 weeks

Shortening of the cervix

22 mm

Funnel shaped expansion of the cervical canal.

31weeks

Residual cervix 9 mm


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Management of Preterm Labor

Four Objectives:

1. Early diagnosis of preterm labor

2. Identify and treat the underlying cause of

preterm labor if possible

3. Attempt to stop labor when appropriate

4. Minimize neonatal morbidity and mortality


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Management - Prolongation of Pregnancy

less than 40% of patients in preterm labor will becandidates for tocolysis

Goal of Tocolytic Therapy

Delay delivery when appropriate

- gain 48 hours for corticosteroids

- transport- optimize personnel


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Management - Tocolysis Contraindicated

contraindication to continuing pregnancy

e.g. severe pregnancy induced

hypertension, chonoamnionitis intra-

uterine fetal death

contraindication to specific tocolytic agents


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Tocolytics - No strong evidence for efficacy

Fluid bolus - small trial (n=48), no detected effect

Ethanol

- small trials, no benefit over placebo

- ritodrine more effective in comparative trials

- concerns re: adverse effects

Sedation - no evidence, concern re: adverse effects


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Tocolytics - No strong evidence for efficacy

Magnesium sulfate

- small, poor quality trials; placebo and comparative- no benefit shown


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Tocolytics - Good evidence for efficacy

-sympathomimetics (ritodrine)

- highly effective for delaying delivery in the short term

- no demonstrated effect on neonatal outcome

PG synthetase inhibitors (indomethacin)- more effective than placebo in delaying delivery

>48 hours and beyond

- no demonstrated positive effect on neonatal outcome

- small trials, concern re: adverse effects

Calcium channel blockers (e.g. nifedipine)


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Side Effects of -mimetics

tachycardia - maternal and/or fetal

headache and nasal congestion

hyperglycemia / hypokalemia

hypotension

pulmonary edema

- multiple gestation

- other interventions

- infection

myocardial ischemia


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Contraindications to -mimetics

Maternal cardiac disease - structural, ischemic, rhythm

Significant antepartum haemorrhage

Poorly controlled medical condition

- type I diabetes mellitus- hyperthyroidism

Contraindication to prolongation of pregnancy

- preeclampsia or other medical indication

- chorioamnionitis, suspected fetal compromise

- mature fetus / imminent delivery / IUFD or anomaly


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Minimizing Neonatal Adverse Outcomes

Respiratory distress syndrome (RDS) is a major

concern with preterm delivery

Incidence of RDS has improved due to newer therapies

RDS plays a role in several other conditions

- intraventricular haemorrhage (IVH)

- necrotising enterocolitis (NEC)

- persistent pulmonary hypertension (PPHN)- other respiratory conditions


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Meta-analysis of Antepartum Steroids

15 trials evaluating antenatal glucocorticoids for the

reduction of RDS in preterm infants (>24 weeks and

< 34 weeks)

an incomplete course of steroids may still be beneficial

P. Crowley CCPC Review No. 02955


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Effect of Corticosteroids on Neonatal Outcomes

RDS

IVH

NEC

Perinatal Infection

Neonatal Death

0.1 1 10

Odds Ratio (95% Confidence Interval)

P. Crowley CCPC Review No. 02955


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Recommendations

Which steroid ?

betamethasone 12 mg IM q 24h x 2 doses (or q 12h)

dexamethasone 6 mg IV q 12h x 4 doses (or q 6h)

Beware

steroids in the presence of infection

steroids in combination with tocolytics in multiplegestation or diabetes


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Recommendations

When should steroid therapy be instituted?

lower gestation limit 22 - 24 weeks

upper gestation limit 34 - 36 weeks

prophylactic administration depends on

diagnosis and risk

repeated administration unknown


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Recommendations

Who is a candidate for antenatal steroid therapy?

Considerations

preterm labour YES cause

preterm PROM YES infection

hypertensives YES urgency

diabetics YES type, sugars

IUGR YES urgencymultiple gestation YES pulmonary edema


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Decision to Transport

Available level of neonatal or obstetrical care

Available transport and skilled personnel

Travel time

Risk of journey - maternal and fetal/neonatal well-being

Risk of delivery en route

- Parity, length of previous labour

- State of cervix

- Contractions

- Response to tocolytics


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Transport Plan

Copies of antenatal forms, lab results, ultrasounds

Communication

- with patient and family

- with receiving physician re: indication, stabilization,optimization, mode of transport, E.T.A.

Appropriate attendant

IV access, indicated medications, appropriate equipment Assess patient immediately prior to transport


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Preterm Delivery

caesarean not indicated on basis of prematurity

recommendation for C/S of breech < 31 weeks not

based on good evidence prophylactic outlet forceps not indicated

routine episiotomy not indicated

personnel skilled in neonatal resuscitation present


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Location of Preterm Birth

Best

Worst

Level III Hospital Nicu)

Level II Hospital

Level I Hospital

During Transport


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Conclusion

Prompt and accurate diagnosis

Identify and treat underlying cause if possible

Attempt to prolong pregnancy if appropriate

Intervene to minimize neonatal mortality and morbidity

- antenatal steroid therapy

- maternal transport

- optimize local resources if unable to transport


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Prelabor Rupture of the

Membranes PROM)


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Objectives

Definition

Diagnosis

Management - Preterm and Term


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Definition

rupture of the membranes before the onset of labor

preterm - < 37 weeks gestation (PPROM) term -37 weeks gestation (TPROM)


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Latent Period

time from rupture until onset of labor

earlier the gestation the longer the latent period

At term - 90% go into labor within 24 hours

At 28 - 34 weeks

50% go into labor within 24 hours

80 - 90% go into labor within 1 week

P t L b


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Etiology of PROM

idiopathic

infection (e.g. bacterial vaginosis)

polyhydramnios

cervical incompetence

uterine abnormality

following cervical cerclage or amniocentesis

trauma

P t L b


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Diagnosis of PROM

history

sterile speculum exam ( avoid digital exam)

glistening, washed out vagina

fluid pooling in posterior fornix free flow from cervix

pH testing of fluid (nitrazine paper) - non specific

ferning

ultrasound - PROM less likely if normal fluid volume

P t L b


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Complications of PROM - Term

fetal / neonatal infection

maternal infection

umbilical cord compression / prolapse

failed induction resulting in cesarean section

Preterm Labor


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Complications of PROM - Preterm

preterm labor and delivery

fetal / neonatal infection

maternal infection

umbilical cord compression / prolapse

failed induction resulting in cesarean section

pulmonary hypoplasia (early, severe oligohydramnios)

fetal deformation

Preterm Labor


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Management - General

assess maternal and fetal well-being

confirm diagnosis

assess cervical status by speculum exam (sterile)

avoid digital cervical exam

assess for conditions requiring concurrent management

e.g. presence of temperature or maternal or

fetal tachycardia

assess for indications for immediate delivery

Preterm Labor


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Management - Term (> 37 weeks) avoid digital cervical exam

assess for infection

consider need for antibiotics if prolongedPROM .

expectant or active management depending on

circumstances and patient preference

Preterm Labor


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Management - Preterm (34-37 weeks) avoid digital cervical exam, consider antenatal strd.

Antibiotic prophylaxis for GBs ampisilin 3 x 500 mg

p.o and erithromicyn 3x250mg po for 7 days.

surveillance for infection - clinical (monitor maternal

temperature and pulse, fetal heart rate)

appropriate antibiotics for chorioamnionitis if develops

Preterm Labor


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Management - Preterm (< 34weeks)

avoid digital cervical exam

steroids

antepartum and intrapartum antibiotics to mother

surveillance for infection - clinical (monitor maternal pulse andtemperature, fetal heart rate, presence of uterine irritability)

appropriate antibiotics for chorioamnionitis if develops

consider transfer to higher level of care center if appropriate

expectant management (possibly outpatient)

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