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7/23/2019 1 Preterm Labor
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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.jpeg7/23/2019 1 Preterm Labor
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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)