Preterm labor Flashcards
preterm labor
general
When a patient goes into labor and is greater than 20 weeks and less than 37 weeks gestational age
Preterm birth complicates 12% of all pregnancies in US
#1 cause of neonatal morbidity and mortality
Causes 75% of neonatal deaths not due to congenital anomalies
*Clinical criteria of regular uterine contractions accompanied by a change in cervical dilation, effacement, or both, or initial presentation with regular contractions and cervical dilation of at least 2 cm.
preterm labor
RF
Preterm labor
Symptoms
Symptoms cramping, initially irregular contractions, pressure in the vagina, and low back pain. Clear-to-pink vaginal discharge is not uncommon and is referred to as the mucus plug or “bloody show.” Spotting can also be demonstrated. As symptoms progress, contractions become more regular and the cervix may dilate, efface
Preterm Labor- Workup
Cervical exam, fetal monitoring, ultrasound
Fetal Fibronectin
Extracellular matrix protein present at the decidual-chorionic interface
Any disruption of this interface due to subclinical infection or inflammation, abruption, or uterine contractions releases fFN into cervicovaginal secretions, which is the basis for its use as a marker for predicting preterm labor/birth
FFN only collect if patient between 24 - 34wk GA!
Positive result: increased risk of PTB within 7 days
Many false positive rates
Good negative predictive value! If negative, highly unlikely patient will go into preterm labor within 7-10 days
Fetal Fibronectin
Symptomatic patients > Negative FFN
Negative predictive value for delivery within…
7d = 99.5%
14d = 99.25
Benefits of a negative test: Less interventions and avoid hospitalizations
Symptomatic patients > Positive FFN
Positive predictable value for delivery within
7d = 12.7%
14d = 16.7%
Benefits of a positive test: identify a group that can be targeted for intervention, opportunity for antenatal steroids, preparation for neonatal care
Preterm Labor- Diagnosis
Patients must have regular uterine contractions along with the presence of:
cervical dilation of 2 cm or greater
cervical length less than 20 mm on transvaginal ultrasound
or cervical length of 20–30 mm on ultrasound with positive fetal fibronectin
Preterm Labor- Management
Hospitalization
Magnesium for Fetal Neuroprotection
Antenatal Corticosteroids
Tocolytic Therapy
PTL
Tocolysis
Reduces strength & frequency of uterine contractions
Not indicated before fetal viability (24 weeks)
Upper limit of use generally 34 weeks
Not indicated for CTX without cervical change
Contraindications
IUFD
Non-reassuring fetal status
Severe preeclampsia
Hemorrhage with hemodynamic instability
Chorioamnionitis
Maternal medical contraindications (agent-specific)
Tocolytics discontinued after 48 hours
Regimens typically used…
24-32 weeks: indomethacin 50-100mg PO or PR x1 🡪 25mg PO Q4-6h
Contraindications: platelet dysfunction/bleeding disorder, hepatic dysfunction, PUD, renal disease
32-34 weeks: nifedipine 30mg PO x1 🡪 10-20mg PO Q4-6h
Contraindications: hypotension, preload-dependent cardiac lesions, LV dysfunction or CHF
Corticosteroids for Fetal lung maturity
Corticosteroids for Fetal Lung Maturity
Betamethasone (and Dexamethasone) has been shown to improve fetal lung maturity and reduce neonatal respiratory distress syndrome (RDS) and mortality in offspring. Subsequent trials have shown that ACS also improves circulatory stability in preterm neonates, resulting in lower rates of intraventricular hemorrhage and necrotizing enterocolitis compared with unexposed preterm neonates.
Steroids increase surfactant and promotes growth of T1 & T2 pneumocytes
Improved lung compliance & volume
Improved gas exchange
Increased surfactant production
Induction of enzymes/receptors to enhance absorption of lung fluid
When to consider antenatal corticosteroids…
Meds options
Pregnancies 24-34 with risk of PTB within 7 days
Includes PPROM, multiple gestations, + FFN
New data: steroids can be given after 34 weeks for certain situations
When to give “rescue” steroids
Single repeat course if < 34wks and increased risk of PTB within 7 days
>14 days has passed since first course
>2 courses is NOT recommended
Regimens:
Betamethasone 12mg IM Q24h x2 doses
Dexamethasone 6mg IM Q12h x4 doses
Magnesium for Neuroprotection
Preterm exposure to magnesium > decreases diagnosis and severity of cerebral palsy
Magnesium only given < 32 weeks
Give it if delivery is likely within 12-24 hrs
Dosing: 6g loading dose»_space; 2g/hour for 12-24 hrs
Preterm Labor Management - Summary
A single course of corticosteroids is recommended for pregnant women between 24 weeks and 34 weeks of gestation who are at risk of delivery within 7 days.
Magnesium sulfate reduces the severity and risk of cerebral palsy in surviving infants if administered when birth is anticipated before 32 weeks of gestation.
The evidence supports the use of first-line tocolytic treatment with calcium channel blockers, or NSAIDs for short-term prolongation of pregnancy (up to 48 hours) to allow for the administration of antenatal steroids
ACOG practice bulletin
Cervical Insufficiency/Incompetence
Recurrent painless cervical dilation leading to 2nd trimester pregnancy losses
Risk factors
Cervical trauma (previous surgery), congenital cervical abnormalities, history of shortened cervix in pregnancy)
Measure Cervical Length: Measure length of cervix every 2 weeks from 16-24 weeks, only indicated for those at risk of cervical shortening or cervical incompetence.
< 2.5cm = short cervix
Treatment:
Cerclage (history indicated or exam indicated)
Supplemental Progesterone
Fetal Growth Restriction (FGR)
Occur in 10% pregnancies
Defined at estimated fetal weight (EFW) < 10%th percentile OR Abdominal circumference measurement < 10 percentile
Various causes
Constitutional
Fetal genetics
Maternal conditions
Hypertensive disorders, placenta insufficiency
Infection
Management: Umbilical artery dopplers
Monitor fetal growth ultrasounds every 2-4 weeks
Monitor NST/ BPP as patients get closer to due date
Timed delivery
Cesarean Section
Birth of fetus through laparotomy then subsequent hysterotomy
Indications:
Previous history of cesarean, labor dystocia, preeclampsia, placenta previa, fetal malpresentation (breech), non reassuring fetal status in labor
**Emergency CS: Decision to incision 30 minutes
Fetus delivered in under 5 minutes
Skin to Uterus: The Layers
Skin Incision: Most common type Pfannenstiel
Transverse incision 2-cm above the pubic symphysis
12-15cm wide
Subcutaneous tissue (fat) > rectus abdominis fascia (connective tissue) > rectus muscle > peritoneum > vesicouterine serosa > uterus (hysterotomy = uterine incision) > membranes (amniotic sac) > delivery of fetus!
Hysterotomy (two most common incision types)
Low transverse incision
Horizontal incision in the lower uterine segment
Classical incision
Vertical incision into the body of uterus above the LUS (lower uterine segment), reaches the fundus
