Preterm Labor

Front 1

What is leading cause of neonatal mortality?

Back 1

preterm labor

Front 2

What causes preterm labor?

Back 2

excessive uterine distension, decidual hemorrhage, activation of maternal and fetal hypothalamic pituitary system, intrauterine infection leading to inflammation
these cause production of uterine and cervical proteases and uterotonins which causes cervical ripening and dilation, weakening of the chorioamniotic membrane which leads to rupture, uterine contractions

Front 3

How does infection cause preterm labor?

Back 3

trigger inflammatory response that releases cytokines, prostaglandins, and proteases which stimulate uterine activity, induce cervix softening dilation, and weaken chorioamniotic membranes

Front 4

Is there genetic predisposition for preterm labor?

Back 4

yes

Front 5

Can thrombin cause preterm labor?

Back 5

yes, associated with vaginal bleeding caused by placental abruption

Front 6

Can increased corticotropin releasing hormone cause preterm birth?

Back 6

yes, from maternal and fetal stress or infection

Front 7

What are symptoms of preterm labor?

Back 7

back ache and uterine contractions

Front 8

Are contractions always detected in preterm labor?

Back 8

not frequently, not painful, not a sensitive marker for preterm labor

Front 9

What can exclude imminent preterm delivery if 24-34 weeks gestation with intact amniotic membranes, and cervical dilation less than 3 cm?

Back 9

negative fibronectin

Front 10

What does fibronectin predict?

Back 10

delivery in next 1-2 weeks

Front 11

What is the strongest predictor of preterm birth?

Back 11

prior preterm birth, 4 fold increase if 1 previous, 6 fold if 2 previous

Front 12

What risk factors for preterm birth?

Back 12

less than 18 or greater than 35
black, low maternal wt before pregnancy, smoking, 2nd or 3rd trimester bleeding, multiple gestation, uterine anomalies
shorter cervix
maternal infections (UTIC, pneumonia)
genital organisms: Gardnerella vaginalis, Chlamydia trachomatis, Neisseria gonorrhoeae, Ureaplasma urealyticum, Trichomonas vaginalis

Front 13

Do preterm deliveries only in occur in pts with risk factors?

Back 13

no, only half do

Front 14

What are tocolytics used for?

Back 14

diminish contractions

Front 15

When is glucocorticoid considered?

Back 15

all women at risk for preterm birth within 7 days and between 24-34 weeks gestation

Front 16

When is tocolytic less likely to be effective?

Back 16

women with cervical dilation greater than 3cm and unsuccessful if pt is in advanced labor (greater than 5cm)

Front 17

What should be ruled out before tocolytic is used?

Back 17

other causes of preterm labor: UTI, choriamnionitis

Front 18

What is most frequent parenteral tocolytic?

Back 18

magnesium sulfate, also prevents and treats eclampsia

Front 19

What level of mag sulfate is needed to relax uterine smooth muscle?

Back 19

maternal serum level 5-8mg/dL

Front 20

How does mag sulfate work as a tocolytic?

Back 20

inhibits myosin ligh chain kinase activity by competition with intracellular calcium, reducing myometrial contractility

Front 21

When is magnesium CI?

Back 21

myasthenia gravis and renal failure

Front 22

How does magnesium compare to beta agonist ?

Back 22

equally effective and better tolerated

Front 23

How is magnesium dose increased?

Back 23

until she has fewer contractions per 10 minutes or max of 4g/hr

Front 24

What should be monitored with mag sulfate?

Back 24

DTR, respiratory rate, urine output, fluid balance (fluid overload), serum concentrations (every 6-12hrs)

Front 25

Why DTR measured?

Back 25

patellar reflex disappears with mag serum concentration between 9 and 10 mg/dL, as long as DTR present no need to measure concentration

Front 26

What is used to prevent inadvertent overdoses from mag sulfate?

Back 26

controlled infusion device to deliver as continuous infusion

Front 27

What toxicities can occur with hypermagnesemia?

Back 27

hypocalcemia and tetany
neuromuscular blockade and respiratory arrest (15-17mg/dL)
cardiac arrest (greater than 17mg/dL)

Front 28

What is used to reverse toxic effects of magnesium sulfate?

Back 28

1g parenteral calcium gluconate

Front 29

What AE from mag sulfate?

Back 29

common: transient hypotension, flushing, sense of warmth, HA, dizziness, lethargy, nystagmus, dry mouth
others: paralytic ileus and pulmonary edema

Front 30

Is pulmonary edema more common in mag sulfate or beta agonist?

Back 30

beta agonist

Front 31

How do fetal concentrations of mag compare to maternal?

Back 31

similar

Front 32

What are most common neonatal AE from mag sulfate?

Back 32

hypotonia and sleepiness

Front 33

What potential role does mag sulfate have?

Back 33

prevention of cerebral palsy

Front 34

Why are B adrenergic agonist not first line for preterm labor?

Back 34

high costs and maternal AE

Front 35

What is the only medication FDA approved for tx of preterm labor?

Back 35

ritodrine, b agonist

Front 36

What are the B2 agonists?

Back 36

ritodrine and terbutaline, bind to B2 receptors in uterine smooth muscle and inhibit smooth muscle cell contractility

Front 37

What can continued use of B agonists lead to?

Back 37

tachyphylaxis

Front 38

What route for terbutaline?

Back 38

IV, SQ, and PO

Front 39

When is SC terbutaline used?

Back 39

mild contraction and cervical dilation less than 2cm

Front 40

When is IV terbutaline used?

Back 40

more severe and frequent contractions anc cervical dilation greater than 2cm

Front 41

Why do B agonists have high incidence of AE?

Back 41

not selective for myometrial B2 adrenergic receptors at pharmacologic doses

Front 42

What maternal AE from B agonists?

Back 42

pulmonary edema, palpitations, tachycardia, myocardial ischemia, hyperglycemia, hypokalemia, and hepatotoxicity

Front 43

How often d/c from B agonists?

Back 43

10%

Front 44

What can pulmonary edema lead to from B agonists?

Back 44

ARDS and death

Front 45

When should B agonist not be used?

Back 45

underlying cardiac disease or arrhythmias, HTN, DM, severe anemia, thyrotoxicosis

Front 46

What AE for fetus?

Back 46

tachycardia, hypotension, hypoglycemia, hypocalcemia
increased risk of neonatal intraventricular hemorrhage

Front 47

What prostaglandins are important regulators of myometrial contractility and cervical ripening?

Back 47

F2alpha and E2

Front 48

What is action of indomethacin?

Back 48

COX1 inhibitor, prostaglandin synthetase inhibitor, decrease prostaglandin production and thereby decrease contractions and inhibit cervical change

Front 49

Indocin

Back 49

indomethacin, prostaglandin synthetase inhbitor

Front 50

What is used for GI upset from Indocin?

Back 50

antacids

Front 51

Does indocin cross placenta?

Back 51

yes, rapidly and approaches maternal levels

Front 52

What AE for indomethacin?

Back 52

decrease fetal urine output leading to oligohydramnios
constriction of ductus arteriosus
increased risk for maternal postpartum hemorrhage

Front 53

When should indomethacin be d/c based the amniotic fluid index?

Back 53

if below 5cm, oligohydramnios

Front 54

When does oligohydramnios resolve?

Back 54

48-72hrs after d/c indomethacin

Front 55

What increases risk of neonatal AE from indomethacin?

Back 55

drug exposure more than 48hrs and used after 32 weeks when premature closure of ductus occurs more frequently

Front 56

When should indomethacin not be used?

Back 56

presence of oligohydramnios or suspected fetal renal or cardiac anomaly

Front 57

When is indomethacin used as tocolytic?

Back 57

second line for preterm between 24-32 weeks with CI to other tocolytics

Front 58

What route is loading dose of indomethacin?

Back 58

rectal or PO

Front 59

What route is maintenance dose of indomethacin?

Back 59

PO

Front 60

How long is indomethacin given?

Back 60

24-48hrs

Front 61

Why might COX 2 inhibitors be more effective than COX 1 inhbitors or nonselective?

Back 61

only amniotic COX2 is increased during labor

Front 62

How do CCB work as tocolytics?

Back 62

decrease calcium influx into uterine smooth muscle and inhibit myometrial contractions

Front 63

What CCB are used as tocolytics?

Back 63

nifedipine (most common) and micardipine

Front 64

What maternal AE for CCB?

Back 64

tachycardia, HA, flushing, dizziness, nausea, hypotension

Front 65

Does nifedipine adversely affect uteroplacental blood flow or fetal circulation?

Back 65

no

Front 66

What DI with CCB?

Back 66

magnesium, may potentiate neuromuscular blockade

Front 67

What is max dose of nifedipine in first hr?

Back 67

40mg in first hr

Front 68

How long is nefedipine used?

Back 68

through week 34

Front 69

How long is magnesium sulfate tx?

Back 69

12-24hrs after successful tocolysis, or the time to complete corticosteroids

Front 70

What is used for chronic tocolytic?

Back 70

continuous SC low dose terbutaline infusion through portable pump

Front 71

Why is glucocorticoid given?

Back 71

increase production of fetal lung surfactan and reduce incidence and severity of RDS

Front 72

What glucocorticoids are used?

Back 72

betamethasone and dexamethasone

Front 73

What other benefits from steroids?

Back 73

decreased intraventricular hemorrhage, necrotizine enterocolitis, neonatal death

Front 74

Why are repeat weekly courses of CS discouraged?

Back 74

decreased birthweight and head circumference, hypothalamic pituitary adrenal axis suppression, deleterious effects on cerebral myelination and lung growth, neonatal death

Front 75

When is CS recommended?

Back 75

preterm labor between 24 and 34 weeks gestation

Front 76

Which CS is preferred?

Back 76

betamethasone, fewer IM injections, greater reduction in RDS

Front 77

When can CS be given in preterm premature rupture of membrane?

Back 77

up to 32 weeks in absence of chorioamnionitis

Front 78

What is used as indicator for fetal lung maturation?

Back 78

phosphatidylglycerol or lecithin to sphingomyelin ratio (L:S) greater than 2

Front 79

When is CS not recommended?

Back 79

greater than 34 weeks unless indication of fetal lung immaturity

Front 80

Why are AB given in preterm labor?

Back 80

treat bacterial vaginosis, occult or documented intra-amniotic infections in preterm premature rupture of membrane, prophylactic against neonatal GBS

Front 81

What is risk from bacterial vaginosis?

Back 81

preterm delivery

Front 82

Are vaginal AB effective for bacterial vaginosis?

Back 82

no

Front 83

What AB must be included in regimen for bacterial vaginosis?

Back 83

metronidazole (Flagyl)

Front 84

Does tx of bacterial vaginosis reduce risk of preterm delivery if no history of preterm birth?

Back 84

no

Front 85

What week should tx for bacterial vaginosis begin?

Back 85

37

Front 86

Where is most bacteria in amniotic fluid and placenta from?

Back 86

vagina

Front 87

When does spontaneous delivery occur when preterm premature rupture of membrane occurs?

Back 87

within 7 days, AB increase this

Front 88

What is sign of choriamnionitis?

Back 88

temp 100.4 (38C) or more

Front 89

How many women are colonized with GBS?

Back 89

10-30% women in vagina or rectum

Front 90

What neonates get GBS?

Back 90

1-2% born to GBS mother

Front 91

What organism causes GBS?

Back 91

Streptococcus agalactiae

Front 92

How is GBS transmitted to fetus?

Back 92

vertical: mother to infant during labor and delivery

Front 93

What is mortality rate of GBS?

Back 93

5-20%

Front 94

What does GBS cause to mother?

Back 94

UTI, amnionitis, endometriosis, wound infection

Front 95

What has reduced incidence of GBS?

Back 95

AB prophylaxis

Front 96

When is mother treated with intrapartum AB for GBS?

Back 96

positive vaginal GBS
or one or more of the following:
previous infant with GBS, GBS bacteriuria during current pregnancy, preterm labor less than 37 weeks, preterm premature rupture of membrane 18hrs or more, intrapartum temp 38 (100.4) or more

Front 97

What is tx if GBS positive and onset of labor less than 37 weeks?

Back 97

Pen V for 48 hrs and intrapartum AB prophylaxis
if no GBS culture, start Pen until result of culture

Front 98

What is optimal prophylaxis for GBS?

Back 98

AB at least 4 or more hrs before delivery

Front 99

What is preferred tx for GBS?

Back 99

Pen G over amp because of narrower spectrum of antimicrobial activity

Front 100

What is required for intrapartum prophylaxis for GBS?

Back 100

AB given immediately before and during delivery

Front 101

When is intrapartum prophylaxis for GBS indicated?

Back 101

previous infant with invasive GBS, GBS bacteriuria during current pregnancy, positive GBS culture during current pregnancy (unless planned cesarean delivery in absence of labor or amniotic membrane rupture is performed), unknown GBS status and any of the following (delivery less than 37 weeks gestation, amniotic membrane rupture 18hrs or more, intrapartum temp 100.4)

Front 102

Is previous pregnancy with positive GBS indicated for tx?

Back 102

no

Front 103

Is planned cesarean delivery in absence of labor or membrane rupture indicated for GBS prophylaxis?

Back 103

no

Front 104

What is recommended tx for GBS?

Back 104

Pen G

Front 105

What is alternative tx for GBS?

Back 105

ampicillin

Front 106

What is tx if pt has pen allergy but not at high risk for anaphylaxis?

Back 106

cefazolin

Front 107

What is tx if pt at high risk for anaphylaxis?

Back 107

clindamycin or erythromycin if susceptible
vanc is resistant to clindamycin or erythromycin or unknown