Preterm Labor Flashcards
Preterm labor?
In nulliparous woman, data sufficient to make diagnosis?
Cervical change and uterine contractions between 20-37 weeks gestation
2 cm dilation + 80% effacement
Preterm labor – next steps? Test?
- Tocolysis
- Identify cause of preterm labor
- Antenatal steroids
- GBS prophylaxis
Fetal fibronectin assay
Tocolysis? Give when? Options?
Pharmacologic agents used to delay Labor
Gestational age less than 34 weeks
Indomethacin, nifedipine, terbutaline, Ritodrine
Antenatal steroids? Give when? Route of administration? Decreases what complications of prematurity?
Betamethasone, dexamethasone
If gestational age less than 34 weeks
IM
RDS, intraventricular hemorrhage
Fetal fibronectin – purpose? Purpose of assay?
Basement membrane protein that binds placental membranes to decidua
Negative result indicates 99% chance of not delivering in next week
Cervical length assessment? Increased risk of preterm delivery if?
Transvaginal ultrasound to measure cervical length
Increased risk of preterm delivery if:1. <25 mm Length of cervix
2. Impinging of the amniotic cavity into the cervix (funneling)
Risk factors for preterm labor?
- Abdominal trauma
- Previous preterm labor, multiple gestation,
- Uterine anomaly, premature rupture of membranes
- cervical cone biopsy
- Hydramnios, pyelonephritis
- African-American
- Cocaine
Magnesium sulfate as tocolytic agent? Proposed mechanism?
Unclear if it is effective
Competitive inhibition of calcium to decrease availability for myometrial contractions
Nifedipine – mechanism? Side effects?
Inhibits voltage activated calcium channels
Pulmonary edema, respiratory depression, neonatal depression (Osteoporosis if long-term use)
Drug classes (and examples) of common tocolytic agents?
- Minerals – magnesium sulfate
- Beta agonist – terbutaline
- Calcium channel blockers – nifedipine
- NSAIDs – indomethacin
- Hormones – 17-alpha-hydroxyprogesterone
Mechanism of action of
- magnesium sulfate
- Terbutaline
- Nifedipine
- Indomethacin
- 17-Alpha-hydroxyprogesterone
- Competitively inhibits calcium
- Agonist for beta-2 receptors
- Inhibits calcium ion influx
- Decreased prostaglandin synthesis
- Inhibits gonadotropin release, maintaining pregnancy
Side effects for:
- magnesium sulfate
- Terbutaline
- Nifedipine
- Indomethacin
- 17-Alpha-hydroxyprogesterone
- Pulmonary edema, neonatal osteoporosis
- Pulmonary edema, hyperglycemia, hypokalemia, tachycardia, increased pulse pressure
- Pulmonary edema, MI, hypotension
- Closure of PDA – leads to pulmonary hypertension, oligohydramnios
- Breast tenderness, abdominal pain, bleeding
Contraindications for:
- magnesium sulfate
- Terbutaline
- Nifedipine
- Indomethacin
- 17-Alpha-hydroxyprogesterone
- Heart problems, diabetes, myasthenia gravis, concurrent calcium channel blocker
- Arrhythmia, hypertension, seizures, diabetes
- Hypotension,concurrent Magnesium
- Third trimester
- Vaginal bleeding
Infections that are associated with preterm delivery?
Gonococcal cervicitis, pyelonephritis, bacterial vaginosis
Patient given tocolytic – now has significant variable decelerations (that weren’t present before) – tocolytic used? Variable decelerations caused by (In general)?
Indomethacin – variable decelerations caused by oligohydramnios, rupture of membranes, labor
Indomethacin associated with decreased amniotic fluid and oligohydramnios
