Clin: Obstetric Complications - Wootton Flashcards
birth that occurs after 20 weeks, but before 36.6 weeks gestation
preterm birth
uterine contractions accompanied with cervical change or cervical dilation 2cm and/or 80% effaced
labor
- preterm if 20-36 weeks
what is the leading cause of infant mortality?
preterm labor
what are the risk factors for PTL?
- african american
- decreased access to prenatal care
- high stress levels, poor nutrition
- previous hx of PTL
- bleeding in first trimester (inflammatory response)
- UTI/genital tract infections
- polyhydramnios (AFI greater than 20)
what are the four main causes of PTL?
- infection
- placental-vascular
- psychosocial stress and work strain
- uterine stretch (polyhydramnios, multiple babies)
what infections are associated with preterm delivery? (4)
- bacterial vaginosis
- GBS
- gonorrhea/chlamydia (link b/w infection and progressive changes in cervical length)
when is it important to use US for routine screening of cervical length?
with hx of PTL or cervical procedure (LEEP or CKC)
what is another screening tool for cervical length?
fetal fibronectin (FFN)
- released from basement membrane of fetal membranes
- released in response to disruption of membranes as with uterine activity, cervical shortening, or infection
- negative predictive value is GOOD, positive predictive value is LOW
alteration of what 3 factors may result in poor fetal growth?
- risk factors for PTL as well as growth restriction and preeclampsia
- immunologic
- vascular
- low resistance connection of spiral arteries
cortisol stimulates early placental corticotrophin-releasing hormone (CRH) gene expression and increased CRH levels are known to do what?
assist in labor at term
what hormone class affects blood flow and causes uterine contractions?
catecholamines
what are the two main risk factors for uterine stretch?
- polyhydramnios
- multiple gestations
what two factors must be present in order to dx PTL?
- uterine contractions
2. cervical change, cervical dilation of 2cm or greater and/or 80% effacement
what are the sx of PTL?
menstrual like cramping, low/dull backache, pelvic pressure, increase in discharge/bloody discharge and uterine contractions
hydration and bedrest can help resolve what in 20% of patients?
contractions
what is the management of PTL?
- GBS culture (give penicillin if needed)
- CBC, UA, urine culture
- US (for fetal presentation, growth, amniotic fluid volume, rule out congenital anomalies)
what meds can be given in PTL?
- MgSO4
- nifedipine
- prostaglandin synthetase inhibitors (indomethacin - only if < 32 weeks)
what is the drug of choice (arguably) in US?
MgSO4
- acts on cellular level, competes with calcium for entry into the cell
- may offer prevention against cerebral palsy
what are the side effects of MgSO4 on mom?
- warmth, flushing
- NV
- respiratory depression
- cardiac conduction defects and arrest at high serum levels
what are the side effects of MgSO4 on baby?
- loss of muscle tone
- drowsiness
- lower APGAR scores (worse on premature infants)
oral agent effective in suppressing preterm labor
- minimal maternal and fetal side effects (HA, flushing, hypotension, tachycardia)
- inhibits slow, inward current of calcium during the second phase of action potential
- may replace MgSO4 as drug of choice
nifedipine
inhibits prostaglandin production that induce myometrial contractions
- used on short term basis (mostly for extreme prematurity)
prostaglandin synthetase inhibitors
- indomethacin most commonly used (orally or rectally)
what are the side effects of indomethacin?
can result in oligohydramnois (decreases fetal renal function)
- can cause premature closure of fetal ductus arteriosus -> result in pulmonary HTN and heart failure
- infants exposed to indomethacin are at greater risk of necrotizing enterocolitis, intracranial hemorrhage
used to mature the fetal lung
- reduces motality and incidence of RDS and intraventricular hemorrhage
- given between 24 and 34 weeks
- either 2 doses of betamethasone, or 4 doses dexamethasone q 12 hrs
glucocorticoids
what is the rescue dose of corticosteroids?
single course of betamethasone is recommended for pregnant women between 34 and 37 weeks gestation, at risk of preterm birth within 7 days, and who have not received a previous course of antenatal corticosteroids
what is the recommended delivery method for preterm infants?
if vertex -> vaginal
if breech -> c-section (d/t increased risk of cord prolapse)