Preterm Birth

Question 1

Dating ultrasound accuracy
Guidelines for redating

<9w
9-14w
14-16w (biometry)
16-22w
22-28
>28

Answer 1

>5 days from LMP
>7 days
>7 days
>10 days
>14 days
>21 days

Question 2

Neonatal complications of PTL

Answer 2

RDS
IVH
PDA
NEC
Sepsis

Question 3

Strongest risk factors for preterm birth

Answer 3

History of preterm birth or PPROM
Short cervical length
Multiples

Question 4

cervical length screening ?

Answer 4

16 to 24 weeks at 1-4 week intervals For Singleton with history of PTB. Recurrence risk 35%

Insufficient data to recommend cervical length screening for multiples

Question 5

Interventions to reduce risk of preterm birth in patients with singleton, Short cervical length and no history of PTB

Answer 5

Vaginal P4
Use for CL <25mm
200mg

Cerclage if CL <10mm or exam indicated 16-24w

Question 6

Interventions for Patient with history of preterm birth

Answer 6

Vaginal progesterone or 17 OHP

Cervical length monitoring 16 to 24 weeks
- if <25, cerclage or vaginal P4

Question 7

Intervention for multiple gestation with history of preterm birth

Answer 7

17 0HP may be beneficial

Insufficient data for cervical length screening

Cerclage may be beneficial for advanced cervical dilation noted on exam

Question 8

Antibiotic regiment for PPROM

Answer 8

Two day course IV ampicillin and erythromycin (azith if not available) followed by five day course of oral amoxicillin and erythromycin (azith)

Question 9

Tocolytics

Magnesium sulfate

Answer 9

Mechanism unknown
6g load then 2g per hour
Don’t use in women with myasthenia gravis or cardiac conduction defects

Calcium gluconate 1g IV over 5-10 min is antidote

Question 10

Terbutaline

Answer 10

Beta 2 agonist
25 mcg q20-30 min x4 doses
SE: maternal tachycardia, hypotension, bronchial relaxation
CI: poorly controlled hyperthyroidism and DM

Question 11

Nifedipine

Answer 11

CCB
20-30mg load then 10mg q6h
SE: nausea, flushing, dizziness, HA, palpitations
CI: heart failure, hypotension, mag sulfate

Question 12

Indomethacin

Answer 12

Cyclooxygenase inhibitor
50-100 mg load then 25 mg q6 h
Can cause premature closure of DA&raquo_space; pulmonary HTN in neonate
Don’t use after 32w
CI: plt dysfunction of bleeding diathesis, asthma, hepatic dysfunction

Question 13

What is the dose for betamethasone?

Dexamethasone?

Answer 13

12 mg IM q24 hrs x2

6mg q12 hrs x4

Question 14

Indication for cerclage placement

Answer 14

1. History of one or more second trimester pregnancy loss as related to painless cervical dilation OR prior cerclage for this indication
2. Painless cervical dilation in the second trimester prior to liability
3. Hx of PTB AND Cervical length less than 25 mm before and 24 weeks or CL <1 cm

Question 15

What is the incidence of preterm birth

Singleton
Twins
Triplets

Answer 15

8%
20%
80%

Question 16

Neonatal survival statistics

24 w
28w

Answer 16

30-50%

90%

Question 17

What is the benefit of steroids?

Answer 17

Decreases RDS, NEC, IVH