Preterm Labor, PROM and Postterm Pregnancy - Hibbs

Question 1

What are the causes of preterm labor?

Answer 1

1) activation of maternal/fetal HPA axis
2) inflammation
3) decidual hemorrhage
4) pathological uterine distension

Question 2

What are risk factors for preterm labor?

Answer 2

1) multiple gestations
2) prior history
3) cervical insufficiency
4) uterine distortion
5) placental abnormalities
6) maternal smoking (PROM)
7) bacterial vaginosis

Question 3

What can be used as a prediction of preterm labor?

Answer 3

1) fFN - fetal fibronectin
a) glycoprotein produced by the amnion
2) cervical length

Question 4

What are the limitations with using fetal fibronectin as a prediction for preterm labor?

Answer 4

1) poor positive predictive value (PPV)
2) great negative predictive value (NPV)
3) used bw 22-34 weeks
4) can’t be done if the patient has had a manual exam, had sex in the last 24 hours etc

Question 5

What about the cervical length is useful in assessing risk for preterm labor?

Answer 5

1) less than 2.5 cm is shortened (avg @ 24 weeks is 3.5 cm)

2) dynamic changes

Question 6

What is not proven effective in preventing preterm labor?

Answer 6

1) prophylactic therapy with tocolytic drugs
2) bed rest
3) hydration

Question 7

When do you used 17-alpha-hydroxyprogesterone caproate to prevent preterm labor?

Answer 7

1) start @ 16-20 weeks until 36 weeks

2) used in patients with documented preterm deliveries

Question 8

Why are steroids given if preterm labor is threatened and which steroid is given?

Answer 8

1) Betamethasone

2) maturation of lungs (and other complications)

Question 9

What is the baby most at risk for after a preterm birth?

Answer 9

1) RESPIRATORY DISTRESS
2) intraventricular hemorrhage
3) necrotizing enterocolitis

Question 10

What is tocolysis?

Answer 10

The inhibition of uterine contractions

Question 11

What is the diagnosis of preterm labor?

Answer 11

1) uterine contraction
2) cervical change
3) before 37 weeks (up to 36 w 2 d)

Question 12

How does Magnesium Sulfate cause tocolysis and what are side effects?

Answer 12

1) competes with calcium for entry into the cells
2) side effects:
a) flushing
b) headaches
c) respiratory depression at high levels

Question 13

How do prostaglandin synthetase inhibitors (indomethacin) cause tocolysis and what are the side effects?

Answer 13

1) decreases PG production by blocking conversion of free AA to PG
2) side effects:
a) premature constriction of ductus
arteriosus (esp after 34 weeks)
b) oligohydramnios

Question 14

How do CCB (Nifedipine) cause tocolysis and what are the side effects?

Answer 14

1) prevents entry of calcium into muscle
2) side effects
a) hypotension and headache
b) decrease in uteroplacental blood flow
c) DO NOT use with Mg Sulfate

Question 15

How do beta-adrenergic agents (terbutaline) cause tocolysis and what are the side effects?

Answer 15

1) increases cAMP concentration in cells therefore decreasing free Ca2++
2) side effects
a) hypotension
b) tachycardia
c) anxiety
d) increased pulmonary edema

Question 16

What is the definition of a postterm pregnancy?

Answer 16

pregnancy that persists beyond 42 weeks

Question 17

What is the most common cause of postterm pregnancy?

Answer 17

inaccurate dating

Question 18

How is a pregnancy dated?

Answer 18

1) gestational age always dated from first day of last menstrual period (LNMP)
2) assumes a 28 day cycle
3) first trimester ultrasound very helpful

Question 19

How accurate is pregnancy dating with ultrasound?

Answer 19

1) Ultrasound at 6-12 weeks accurate within 3-5 days

2) ultrasound at 12-20 weeks accurate within 10 days

Question 20

What are the babies risks with a postterm pregnancy?

Answer 20

1) macrosomia
2) shoulder dystocia
3) meconium aspiration syndrome
4) oligohydraminos

Question 21

What is the definition of macrosomia and what is a common cause?

Answer 21

1) fetal weight greater than 4,000-4,5000 g
a) 8lbs 13 oz to 10lbs
2) diabetes and genetic factors

Question 22

Does induction at 39 weeks or elective C section reduce to birth trauma from macrosomia?

Answer 22

NO - except in diabetics

Question 23

What is shoulder dystocia?

Answer 23

impaction of anterior shoulder against the pubis symphysis during delivery

Question 24

What are the consequences of shoulder dystocia?

Answer 24

1) Erb-Duchenne Palsy (waiters tip)
a) C5 and C6
b) paralysis of infraspinatus, deltoid and
flexor muscles of the forearm
2) Klumpke’s Palsy
a) C8 and T1
b) hand paralysis

Question 25

What is oligohydraminos and what are its risks?

Answer 25

1) AFI less than 5cm

2) risk of cord compression, uteroplacental insufficiency and meconium aspiration

Question 26

When does amniotic fluid reach its maximal volume?

Answer 26

34-36 weeks

Question 27

How do you manage a postterm pregnancy?

Answer 27

1) at 41 weeks
a) induce OR
b) antepartum fetal surveilance

Question 28

How do you diagnos PROM?

Answer 28

1) History - gush of fluid or steady leaking
2) speculum exam - pooling of fluid
3) nitrazine test - uses pH to distinguish amniotic fluid from other fluids
4) Fern test - Na+ Cl- pattern

Question 29

After 16 weeks what produces most amniotic fluid?

Answer 29

Fetal urine

Question 30

What are the functions of amniotic fluid?

Answer 30

1) protects against infection, trauma and umbilical cord compression
2) allows for fetal movement and fetal breathing which allows skeletal development and lung maturation

Question 31

What is the definition of PROM?

Answer 31

rupture of the chorioamniotic membrane before onset of labor

Question 32

What are risks for PROM?

Answer 32

1) smoking doubles the risk
2) short cervix
3) prior preterm delivery
4) hydramnios
5) multiple gestations
6) bleeding early in pregnancy

Question 33

What is the biggest and most concerning complication of PROM?

Answer 33

INFECTION

also cord prolapse and placental abruption

Question 34

What is chorioamnionitis?

Answer 34

infection of fetal membranes or amniotic fluid

fetal sepsis is associated with risk of perventricular leukomalacia and cerebral palsy

Question 35

What are the signs and symptoms of chorioamnionitis?

Answer 35

1) fever > 100.4
2) maternal or fetal tachycardia
3) uterine tenderness
4) contractions

Question 36

What is the treatment for chorioamnionitis?

Answer 36

IV antibiotics and delivery

Question 37

What is the management of PROM?

Answer 37

1) if gestational age > 34 weeks induce labor if it does not ensure within 24 hours and give GBS prophylaxis
2) 24-33 weeks - GBS prophylaxis, corticosteroids, antibiotics to prolong latency