Transcript Preterm Labor

Preterm Labor
Obstetrics & Gynecology Hospital of Fudan University
Xu Huan
Introdution
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Labor and delivery between 28 – 36+6 weeks
5%-10%
be the leading cause of perinatal morbidity and
mortality
Survival rates have increased and morbidity has
decreased because of technologic advances
Incidence
(6%-10%)
Definition
(WHO)
• Spontaneous : 40-50%
• PROM
: 25-40%
• Obstetrically indicated : 20-25%
• Preterm labor is the
presence of contractions of
sufficient strength and
frequency to effect
progressive effacement and
dilatation of the cervix
between 20 and 37 weeks’
gestation
Survival by gestational age among
live-born resuscitated infants
In: Creasy, Resnik . Maternal – Fetal Medicine, 2009
Pathophysiology
The preterm parturition syndrome. Multiple pathologic
processes can lead to activation of the common pathway of
parturition.
In: Creasy, Resnik . Maternal – Fetal Medicine, 2009
Ascending intrauterine infections
stage I changing flora vagina/cervix,
II Microorganism alocated between
the amnion and chorion, III intra
amniotic infection, IV fetal invation
Infections associated with preterm delivery
Genital
Intra-uterine
Extra-uterine
* Bacterial vaginosis (BV)
* Group B streptococcus
* Chlamydia
* Mycoplasmas
* Ascending (from genital tract)
* Transplacental (blood-borne)
* Transfallopian (intraperitoneal)
* Iatrogenic (invasive procedures)
* Pyelonephritis
* Malaria
* Typhoid fever
* Pneumonia
* Listeria
* Asymptomatic bacteriuria
In:Jane Norman.Preterm labor 2005
Stretch
Integrins
Inflammation
↑IL-1β
↑TNF-α
Abruption
Thrombin
↑COX2
↓ PGDH
↓ PR-B
Stress
↑ CRH
↑ Estrogen
↑ MMPs
↑ IL-6 and 8
PTL or PPROM
Principal biomechanical mechanisms responsible for chain pathways of preterm parturition
COX2=cyclooxygenase2, PGDH=prostaglandin dehydrogenase PR-B=Progesteron
receptorB.CRH=corticotropin releasing hormon MMPs=matrix metallo proteinase
In: Creasy, Resnik . Maternal – Fetal Medicine, 2009
Risk Factors(1)
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Previous preterm delivery
Low socioeconomic status
Maternal age <18 years or >40 years
Preterm premature rupture of the membranes
Multiple gestation
Maternal history of one or more spontaneous
second-trimester abortions
Maternal complications (medical or obstetric)
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Lack of prenatal care
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Risk Factors(2)
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Uterine causes
 Myomata
(particularly submucosal or subplacental)
 Uterine septum
 Bicornuate uterus
 Cervical incompetence
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Abnormal placentation
Risk Factors(3)
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Infectious causes
 Chorioamnionitis
 Bacterial vaginosis
 Asymptomatic bacteriuria
 Acute pyelonephritis
 Cervical/vaginal colonization
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Fetal causes
 Intrauterine fetal death
 Intrauterine growth retardation
 Congenital anomalies
Diagnosis
Documented uterine contractions(4 per 20
minutes or 8 per 60 minutes)
 Documented cervical change (cervical
effacement of 80% or cervical dilatation of
2cm or more)
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Forecast
uterine activity monitoring.
 Ultrasound Examination of Cervical length
 Fetal Fibronectin
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PRETERM LABOR 
Most mortality and
morbidity is
experienced by babies
born before 34 weeks
Major Risks of Preterm Delivery
Death
Respiratory
distress
syndrome
Necrotising
enterocolitis
Jaundice
Hypothermia
Hypoglycaemia
Infection
Retinopathy of
prematurity
Goldenberg, Obstetrics & Gynaecology 11-2002
Treatment(1)
An initial assessment: ascertain cervical
length and dilatation and the station and
nature of the presenting part
 Bed Rest : be placed in the lateral
decubitus position
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Although bed rest is often prescribed for
women at high risk for preterm labor and
delivery, there are no conclusive studies
documenting its benefit.
 A recent meta-analysis found no benefit to
bed rest in the prevention of preterm labor
or delivery.
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Treatment(2)
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Tocolytic therapy
 Magnesium
sulfate (Intracellular calcium
antagonism) has become the drug of choice
for initiating tocolytic therapy.
 Terbutaline (Bricanyl) Beta2-adrenergic
receptor agonist sympathomimetic; decreases
free intracellular calcium ions
 Nifedipine(Procardia) Calcium channel
blocker
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Tocolytic Therapy
 Prostaglandin
synthetase inhibitors:
indomethacin, administered both orally and
rectally
 Ritodrine (Yutopar) Same as terbutaline
 Nifedipine Indomethacin (Indocin)
Prostaglandin inhibitor
Tocolytic therapy may offer some short-term
benefit in the management of preterm labor.
 A delay in delivery can be used to administer
corticosteroids to enhance pulmonary maturity
and reduce the severity of fetal respiratory
distress syndrome,
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also be used to facilitate transfer of the
patient to a tertiary care center
 No study has convincingly demonstrated
an improvement in survival, long-term
perinatal morbidity or mortality, or neonatal
outcome with the use of tocolytic therapy
alone.
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Potential Complications Associated With the Use
of Tocolytic Agents :
Magnesium sulfate
• Pulmonary edema
• Profound hypotension*
• Profound muscular paralysis*
• Maternal tetany*
• Cardiac arrest*
• Respiratory depression*
Beta-adrenergic agents
• Hypokalemia
• Hyperglycemia
• Hypotension
• Pulmonary edema
• Arrhythmias
• Cardiac insufficiency
• Myocardial ischemia
• Maternal death
Indomethacin (Indocin)
• Renal failure
• Hepatitis
• Gastrointestinal bleeding
Nifedipine (Procardia)
• Transient hypotension
Treatment(3)
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Corticosteroid Therapy
 Dexamethasone
and betamethasone
 for fetal maturation reduces mortality, respiratory
distress syndrome and intraventricular hemorrhage
in infants between 28 and 34 weeks of gestation.
 benefits start at 24 hours and last up to seven days
after treatment
 The potential benefits or risks of repeated
administration of corticosteroids after seven days
are unknown.
Treatment(4)
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Antibiotic Therapy
 women
who received antibiotics sustained
pregnancy twice as long as those who did not
receive antibiotics
 had a lower incidence of clinical amnionitis.
 poor fetal outcome (death, respiratory
distress, sepsis, intraventricular hemorrhage
or necrotizing colitis) occurred less frequently
in women receiving antibiotics
Treatment(5)
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Labor and deliverey
 With modern neonatal care, the lower limit of potential
viability is 24 weeks or 500g, although these limits vary with
the expertise of the neonatal intensive care unit.
 Continuous fetal heart monitoring and prompt attention to
abnormal fetal heart rate patterna are extremely important.
 With a vertex presentation, vaginal delivery is preferred.
 Use of outlet forceps and an episiotomy to shorten the
second stage are advocated.
 Cesarean section for delivery of the very low birth weight
baby
 For the breech fetus estimated at less than 1500g, neonatal
outcome is improved by cesarean section
Premature of membrane
Definition
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Premature rupture of the membranes
(PROM) is defined as amniorrhexis
(spontaneous rupture of membranes) prior
to the onset of labor at any stage of
gestation
Incidence
PROM occurs in about 10-15% of all
delivery
 PROM is associated with 10% of term
pregnancy
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Cause of PROM(1)
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The cause of PROM is not clearly
understood, perhaps associated with the
follow factors:
 Trauma
 Sexual
intercourse (particularly in the late
gestational weeks)
 lax of internal os of uterine
Cause of PROM(2)
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Vaginal infection due to bacteria, virus, TOXO, CMV,
HPV, HSV, et al STDs sexually transmitted diseases
play an important role in the cause of PROM, because
such infections are more commonly found in women with
PROM than in those without PROM
Increased of intra-uterine pressure (such as multiple
pregnancy and hydraminios)
Abnormalities in presentation and position
Cause of PROM(3)
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Smoking the risk of PROM is at lease doubled in women
who smoke during pregnancy
Other factors for PROM include the follow
 Prior PROM
 A short cervical length
 Prior preterm delivery
 Bleeding in early pregnancy
Manifestation and Diagnosis
Fluid passing through the vagina suddenly, and then small amounts
of fluid flow through the vagina intermitently, particularly when the
increased of abdorminal pressure (cough, sneeze, et al)
 Intermittent urinary leakage is common during pregnancy, especially
near term
 Increased vaginal secretions in pregnancy
 Perineal moisture
 Increased cervical discharge
 Urinary incontinence
 Vesicovaginal fistula
May be mistaken for the fluid
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Experimental Test(1)
The Nitrazine test uses pH to distinguish amniotic fluid
from urine and vaginal secretions, the paper turns dark
blue in response to the amniotic fluid
Amniotic fluid is quite alkaline having a pH above 7.0, but
vaginal secretions in pregnancy usually have pH values
of less 6.0
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Experimental Test(2)
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The “fern” test : placing a sample on a
microscopic slide, air drying, and examining
for ferning
 The
amniotic fluid does fern
 The other fluid does not fern
Risk of PROM
Preterm labor: 75%
 Intrauterine infection(chorioamnionitis, 3050% of case)
 Puerperal infection
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Fetal and neonatal complications
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Fetal and neonatal pneumonia, sepsis
Neonatal respiratory distress syndrone
Neurologic dysfunction
Intracranial hemorrhage
Prolapse of umbilical cord
Abruptio placenta
Evaluation
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The gestational age( LMP, ultrasound and uterus fundal height
measurement)
The presence of uterine contractions (abdominal examination)
The amount of amniotic fluid (ultrasound)
Fetal heart rate (FHR monitor)
Fetal maturity (L/S or PG)
The likelihood of chorioamnionitis (white blood cell count)
The likelihood of prolapse of umbilical cord
Management(1)
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Conservative expectant management
Management of chorioamnionitis
Tocolytic therapy
Use of corticosteroids
Labor and delivery
Surfactant therapy
Management(2)
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If PROM occurs at term(37 weeks’ gestational age or more), awaiting
the onset of spontaneous labor for 12-24h should be considered,
because spontaneous labor will ensue in 90% of patients within 24
hours
If the time from PROM to the inset of labor exceeds 24h, induction of
labor should be considered by oxytocin
If the evaluation suggests intrauterine infection or chorioamnionitis,
antibiotic and delivery are indicated and the antibiotic prescribed
should have a broad spectrum of coverage
If the infant is a preterm breech, and the onset of PROM occurs after
30 weeks’ of gestational, possibly by ceasarean delivery
Management(3)
If the gestational age is less 30 weeks’,
vaginal deliverly should be chosen
 If the fetus is significantlypreterm and the
absence of infection, expectant
management is generally chosen
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Management(4)
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Patients must be assessed carefully
 Uterine
tenderness daily
 Electronic fetal monitoring used frequently
 Fetal movement monitoring by the mother
 Frequent ultrasound assessment helps to determine
amniotic fluid
 Frequently WBC counts, usually daily for several days
 Antibiotic should be used and antibiotic therapy may
prolong the latency period after preterm PROM and
improve the perinatal outcome
Management(5)
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To enhance fetal pulmonary matrurity in
patients with preterm PROM
 Corticosteroid
therapy (such as
betamethasone and dexamethasone) is
generally recommended in patients whose
gestational age is 34 weeks’ or less