Obgyn Preterm Labor

Front 1

preterm birth def?

Back 1

delivery that occurs prior to 37 weeks of gestation
- most common cause of perinatal morbidity and mortality in the US

Front 2

what is the most common cause of perinatal morbidity and mortality in the US?

Back 2

preterm birth (before 37 weeks)- 11-12% of babies are premies-- represents 75% of perinatal mortalities and 50% of long term neuro impairments in kids

Front 3

complications of preterm birth

Back 3

1. respiratory distress syndrome
2. intraventricular hemorrhage
3. necrotizing entercolitis
4. sepsis
5. neuro impairment
6. seizures
long term complications: bronchopulmonary dysplais and developmental abns such as cerebral palsy

Front 4

2 categories of preterm births

Back 4

1. spontaneous (PPROM (25-40%) or preterm labor with intact membranes (40-50%)
2. indicated - done for maternal or obstetrical complications (20-30%)

Front 5

preterm labor def

Back 5

presence of regular uterine contractions that occur before 37 weeks of gestation and associated with cervical changes

Front 6

Prediction of Preterm Labor (3)

Back 6

1. increased conc of fetal fibronectin (fFN) in cervical mucous
2. TVS showing decreased cervical length
3. bacterial vaginosis

Front 7

what is fetal fibronectin?

Back 7

extracellular glycoprotein found in cervical mucous in early pregnancy and then again near term

Front 8

what does a rise in preterm fFN indicate?

Back 8

increased likelihood of birth between 22 and 34 weeks of gestation and within 7-14 days of the test

Front 9

how should fFN be used?

Back 9

it should be used to rule out preterm labor as it has a high NPV but a very low PPV.

Front 10

1. What is bacterial vaginosis?
2. what is its significance?
3. When should it be treated?

Back 10

1. alteration in vaginal flora that occurs in 40% of pregnant women
2. associated with preterm labor
3. when the woman is symptomatic or has a high risk for preterm labor

Front 11

Is widespread screening and treatment for BV indicated?

Back 11

NO-- not in asymptomatic low risk women! even if they had previous preterm birth

Front 12

What can be used to prevent preterm labor? Are they effective?

Back 12

Tocolytic drugs, bed rest, hydration and sedation.
NONE ARE EFFECTIVE

Front 13

In women at very high risk for preterm labor with h/o previous preterm birth, what can be given as prevention?

Back 13

weekly IM progesterone starting at 16-20 weeks and continuing until 36 weeks.

Front 14

what may be effective in preventing preterm labor in women with TVS proven cervical shortening?

Back 14

vaginal progesterone

Front 15

tocodynamometer

Back 15

external electronic fetal monitor that can be used to quantify the frequency and duration of contractions

Front 16

If preterm labor is suspected, what should be done?

Back 16

1. External contraction monitor,
2. cervical speculum exam (do this before digital exam if PROM expected)--
3.repeat cervical exams for changes-- minimize variability-- try to have person do the exams
4. UA and culture-- tx UTIs
5. vag/rectal culture for GBS
6. If hx or PE consistent-- neisseria gonorrhea and chlamydia testing
7. US exam for fluid level, presentation, placenta location, cervical length etc

Front 17

what is chorioamnionitis? how can it be detected? what is it assoc with?

Back 17

intra-amniotic fluid infection, can be detected by amniocentesis. assoc with pre-term labor

Front 18

Presence of what in amniotic fluid may indicate infection?

Back 18

decreased glucose, increased lactate dehydrogenase (LDH), increased WBCs, bacteria

Front 19

If there is a high degree of intrauterine infection what should be done?

Back 19

delivery regardless of gestational age
(tocolysis not appropriate)- may get tests to assess for fetal lung maturity during amniocentesis

Front 20

How often does preterm labor resolve spontaneously?

Back 20

50% of the time

Front 21

What is the most commonly used tocolytic?

Back 21

magnesium sulfate (although use of nifedipine is increasing)

Front 22

How long do the effects of tocolytics last?

Back 22

usually no more than 2-7 days-- but this allows for administration of corticosteroids to mother to promote fetal lung maturity

Front 23

What are contraindications to the use of tocolytics?

Back 23

1. advanced labor
2. mature fetus
3. severely anomlaous fetus (lethal congenital abn)
4. intrauterine infection
5. significant vaginal bleeding
6. severe preeclampsia
Also take into account
7. placental abruption
8. advanced cervical dilation
9. placental insufficiency

Front 24

When should corticosteroids be given for preterm labor? Why? When is this maximally effective?

Back 24

from 24-32 (or 34) weeks gestation to enhance fetal lung maturity
- use either betamethasone or dexamethasone
- other benefits of CS tx= dec risk of intraventricular hemorrhage and necrotizing entercolitis
- max effect if given within 7 days of birth-- but no repeat weekly doses recommended

Front 25

Magnesium sulfate
1. MOA
2. SE
3. when CI?

Back 25

1. competes with calcium for entry into cells
2. flushing, HAs, resp or cardiac depression at high levels
3. high degree of safety but CI in hypocalcemia and myasthenia gravis

Front 26

Prostaglandin synthetase inhibitors (e.g. indomethacin)
1. MOA
2. SE

Back 26

2nd line therapy--
1. decreases PG production by blocking conversion of arachadonic acid to PG
2. premature constriction of ductus arteriosus especially after 34 weeks, if prolonged exposure >72 hours then may have reversible fetal renal dysfunction and resultant oligohydramnios

Front 27

nifedipine
1. MOA
2. SE
3. when CI?

Back 27

1. calcium channel blocker
2. hypotension and HA- possible decrease in uteroplacental blood flow, fetal hypoxia and hypercarbia
3. may potentiate effects of Mag

Front 28

Ritodrine and terbutaline
1. MOA
2. SE
3. when CI?

Back 28

beta-adrenergic agents that increase cAMP in cells-- decreasing free calcium
2. hypotension, tachycardia, anxiety, chest pain and tightening, increased pulm edema infrequently,
3. relative CI in patient with CAD and/or renal failure