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Transcript
Preterm Labor
International
Preterm Labor
Preterm Labor
International
Objectives
• Definition and Incidence
• Etiology
• Diagnosis
• Management
- Delaying delivery
- Promoting fetal maturity
- When to transfer
- Delivery
Preterm Labor
International
Definition
• regular uterine contractions accompanied by
progressive cervical dilatation and/or
effacement at less than 37 weeks gestation
 20 to 50% of PTL diagnosis is incorrect
Preterm Labor
International
Dilemma
• interventions to stop preterm labor are not
particularly effective - especially when not
instituted early
'Solution'
• diagnosis based on some degree of uterine activity
combined with a single cervical exam suggesting
early dilatation or effacement
Preterm Labor
International
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 vaginal
bleeding until _______ of placenta is known
Preterm Labor
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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)
Preterm Labor
International
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
Preterm Labor
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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
Preterm Labor
International
Incidence
• preterm delivery occurs in about 7% of pregnancies
• there has been little change in this rate despite new
technologies
Preterm Labor
International
Significance
• preterm birth accounts for 75% of perinatal mortality
• significant longterm neonatal/pediatric sequelae
- CNS and neurodevelopmental
- respiratory
- blindness and deafness
Preterm Labor
International
Etiology
•
•
•
•
•
•
•
•
Idiopathic
Antepartum haemorrhage
Preterm prelabor rupture of membranes
Chorioamnionitis
Multiple pregnancy / Polyhydramnios
Incompetent cervix / Uterine Anomaly
Maternal disease
Fetal anomaly
Preterm Labor
International
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
Preterm Labor
International
Management - Prolongation of Pregnancy
 less than 40% of patients in preterm labor will be
candidates for tocolysis
Goal of Tocolytic Therapy
•
Delay delivery when appropriate
- gain 48 hours for corticosteroids
- transport
- optimize personnel
Preterm Labor
International
Management - Tocolysis Contraindicated
• contraindication to continuing pregnancy
e.g. severe pregnancy induced
hypertension, chonoamnionitis intrauterine fetal death
• contraindication to specific tocolytic agents
Preterm Labor
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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
Preterm Labor
International
Tocolytics - No strong evidence for efficacy
• Magnesium sulfate
- small, poor quality trials; placebo and comparative
- no benefit shown
Preterm Labor
International
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)
Preterm Labor
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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
Preterm Labor
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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
Preterm Labor
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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
Preterm Labor
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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
Preterm Labor
International
Effect of Corticosteroids on Neonatal Outcomes
RDS
IVH
NEC
Perinatal Infection
Neonatal Death
0.1
P. Crowley CCPC Review No. 02955
1
10
Odds Ratio (95% Confidence Interval)
Preterm Labor
International
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 multiple
gestation or diabetes
Preterm Labor
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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
Preterm Labor
International
Recommendations
Who is a candidate for antenatal steroid therapy?
preterm labour
preterm PROM
hypertensives
diabetics
IUGR
multiple gestation
YES
YES
YES
YES
YES
YES
Considerations
cause
infection
urgency
type, sugars
urgency
pulmonary edema
Preterm Labor
International
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
Preterm Labor
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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
Preterm Labor
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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
Preterm Labor
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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
Preterm Labor
International
Prelabor Rupture of the
Membranes (PROM)
Preterm Labor
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Objectives
• Definition
• Diagnosis
• Management - Preterm and Term
Preterm Labor
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Definition
• rupture of the membranes before the onset of labor
– preterm - < 37 weeks gestation (PPROM)
– term
-  37 weeks gestation (TPROM)
Preterm Labor
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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
Preterm Labor
International
Etiology of PROM
• idiopathic
• infection (e.g. bacterial vaginosis)
• polyhydramnios
• cervical incompetence
• uterine abnormality
• following cervical cerclage or amniocentesis
• trauma
Preterm Labor
International
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
Preterm Labor
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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 prolonged
PROM
• expectant or active management depending on
circumstances and patient preference
Preterm Labor
International
Management - Preterm (34-37 weeks)
• avoid digital cervical exam
• consider antenatal steroids
• intrapartum antibiotic prophylaxis
• surveillance for infection - clinical (monitor maternal
temperature and pulse, fetal heart rate)
• appropriate antibiotics for chorioamnionitis if develops
Preterm Labor
International
Management - Preterm (< 34weeks)
• avoid digital cervical exam
• steroids
• antepartum and intrapartum antibiotics to mother
• surveillance for infection - clinical (monitor maternal pulse and
temperature, 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)
Preterm Labor
International
Antibiotic options are:
Iv Penicillin G 5 million units q 4-6h preferred
or
Iv Ampiullin 2g followed by 1 g q 4h
or
IV Clindamyin 600 ng q 8h
Women with suspected chorioamnitonitis require broader
range spectrum antibiotic coverage