PRETERM LABOUR

Question 1

What is the definition of preterm labour?

Answer 1

Labour occurring after 24 weeks and before 37 weeks of pregnancy.

Question 2

Up to what point of gestation should attempts be made to stop a premature labour and why should these attempts be made?

Answer 2

Up to 34+0 weeks

Need to delay long enough to administer corticosteroids to the mother, which will boost fetal lung surfactant production and therefore reduce neonatal respiratory distress.

Question 3

What corticosteroids can be given to mothers in cases of premature labour to increase fetal surfactant production?

Answer 3

Betamethasone or dexamethasone.

Two IM injections given 12-24 hours apart

Question 4

What is the mortality rate of preterm babies?

Answer 4

42 in 1000 livebirths

Question 5

What is the incidence of preterm labour in England and Wales?

Answer 5

7.6% but this figure is increasing

Question 6

What are the risk factors for premature labour?

Answer 6

Previous preterm labour
Smoking
Low SEC
BMI below below 19
Lack of social support
Afro-Caribbean ethnicity
Extremes of reproductive age (less than 20 or more than 35)
Domestic violence
Bacterial vaginosis
Chronic medical conditions

Question 7

What are the main causes of preterm delivery?

Answer 7

Infection eg chorioamnionitis, maternal pyelonephritis

Uteroplacental ischaemia eg abruption

Uterine overdistension eg polyhydramnios, multiple pregnancy

Cervical incompetence

Fetal abnormality

Iatrogenic - because of threat to mother or babies life eg pre-eclampsia

Question 8

What are the main pathogens implicated in preterm labour?

Answer 8

Sexually transmitted: Chlamydia, Trichomonas, Syphilis, Gonorrhea

Enteric organisms: E. coli, Strep fecalis

Bacterial vaginosis: Gardnerella, Mycoplasma and anaerobes

Group B streptococcus (would be very heavy growth)

Question 9

What do we call palpable uterine contractions where the cervix remains closed?

Answer 9

Threatened preterm labour

Question 10

What would you examine in a pregnant women who presents with symptoms consistent with preterm labour?

Answer 10

Abdominal tenderness 
Uterine tenderness
Uterine tone
Uterine contractions
Fetal lie, presentation and engagement

Question 11

What investigations should you do in a pregnant women who appears to be having preterm labour? Why?

Answer 11

Ultrasound - to check abnormal lie and presentation

Cardiotocography - if 27 weeks of gestation or more to check fetal heart

Kit to check for presence of fetal fibronectin - the absence of this would indicate that delivery is less likely which may assist management decisions with regard to tocolysis

Urinalysis - check for UTI infection

Question 12

What is the 11 point management checklist (including investigations) for a patient who presents with threatened preterm labour?

Answer 12

1. Assess for signs of precipitant - sepsis, polyhydramnios, abruption, pre-eclampsia
2. Take bloods and do urinalysis
3. Determine frequency and regularity of contractions
4. Perform sterile speculum to examine cervix (open or closed). Take high vaginal and endocervical swabs.
5. Start fetal heart monitoring
6. Ascertain fetal presentation (breech or cephalic) with ultrasound
7. Give corticosteroids
8. Give Abx if ruptured membrane or sepsis
9. Consider tocolysis
10. Contact paediatricians
11. Discuss mode of delivery.

Question 13

What does tocolysis mean?

Answer 13

The administration of drugs to reduce uterine activity

Question 14

What are the factors that determine whether tocolysis is necessary in a women is is going into preterm labour?

Answer 14

Cervical dilatation

The need to administer steroids and allow time for them to be effective

Need for in utero transfer (breech)

Question 15

What are the different drugs that can be used as tocolytics, drugs that try and stop contractions in women who have gone into preterm labour? For each class give an example that is used.

Answer 15

Oxytocin receptor antagonists - atosiban

Calcium channel blockers - nifedipine (not licenced in the UK)

Beta agonists - salbutamol, ritodrine, terbutaline (IV)

NSAIDs (prostaglandin inhibitors) - indomethacin

Nitric oxide donors - GTN (transdermal patch)

Question 16

What are the potential side effects of oxytocin receptor antagonists, used as tocolytics?

Answer 16

8% of women experience headaches

Question 17

What are the potential side effects of calcium channel blockers such as nifedipine when used as tocolytics?

Answer 17

Headache
Flushing
Tremor

Question 18

What are the potential side effects of beta agonists such as salbutamol when used as tocolytics?

Answer 18

Side effects are very common (80% of women):

Tachycardia (both mother and fetus)
Headache
Tremor
Hyperglycaemia
Hypokalaemia
Pulmonary oedema
MI

Question 19

What are the potential side effects of NSAIDs such as indomethacin when used as tocolytics?

Answer 19

Mother:
Heartburn
Nausea

Fetus:
Premature closure of ductus arteriosus
Reduced renal function causing oligohydramnios

Question 20

What are the contraindications for the use of tocolytics?

Answer 20

Maternal illness that would be helped by delivery (eg pre-eclampsia)

Evidence of fetal distress

Chorioamnionitis - intra-amniotic infection

Significant vaginal bleeding, particularly if abruption is suspected

Already ruptured membranes

Question 21

Should all women who go into preterm labour be given antibiotics?

Answer 21

Those women whose membrane has ruptured before term should have prophylactic erythromycin.

If membrane is intact, the mother should be screened for infection with vaginal and cervical swabs and blood cultures if pyrexial) and only given antibiotics if there are signs of infection.

Question 22

What is cervical incompetence or insufficiency and why is it an issue in pregnancy?

Answer 22

This is when the cervix starts to shorten and open too early during a pregnancy. It can causing either a late miscarriage or preterm birth by allowing the membrane to prolapse and then rupture.

Question 23

How can we treat cervical incompetence or insufficiency?

Answer 23

Cervical cerclage can be performed. This is the insertion of a suture into the cervix to reduce the prolapsed membrane.

Question 24

How should preterm babies be delivered?

Answer 24

There is no evidence to suggest that caesarian section is any safer than vaginal birth in preterm babies.

Question 25

What does PPROM stand for with regard to obstetrics?

Answer 25

Preterm prelabour rupture of membranes

Question 26

What is the principal issue with preterm prelabour rupture of the membrane?

Answer 26

Sepsis of both the mother and the fetus.

Question 27

How do you manage a patient with preterm prelabour rupture of the membrane?

Answer 27

Check fetal lie and presentation - risk of cord prolapse

Digital examination should not be done - unless there are obvious signs of labour - due to risk of infection introduction

Check for symptoms of clinical chorioamnionitis (fever, rigors, green or brown or foul smelling vaginal loss, tender uterus on palpation)

CTG

Blood tests

Administration of prophylactic erythromycin / treat sepsis

Administration of corticosteroids to improve fetal lung maturity

Question 28

How long after preterm prelabour rupture of membrane will a women normally go into labour?

Answer 28

Within 72 hours

Question 29

If a women whose membrane ruptures preterm and prelabour does not go into labour within 72 hours at what point is the target delivery date?

Answer 29

34+0 weeks

Either by induced labour or caesarian section.

Question 30

What tocolytics are used in women with PPROM?

Answer 30

None. They are never used.

Question 31

What antibiotics should be avoid in someone with PPROM due to their association with necrotising enterocolitis in the infant?

Answer 31

Co-amoxiclav