Preterm Delivery

Question 1

Define preterm delivery

Answer 1

Delivery between 24-37wks

Question 2

What is the incidence of preterm delivery?

Answer 2

5-8% deliver preterm (but a further 6% of deliveries present preterm with contractions but deliver at term)

Question 3

List the complications for the baby of preterm delivery

Answer 3

1. Neurological:
   - HIE
   - Retinopathy of prematurity
   - CP
   - IVH
2. Respiratory:
   - RDS
   - Chronic lung disease
3. GI:
   - NEC
4. Haematological:
   - Jaundice
   - Anaemia
5. Infection:
   - Sepsis
   - RTI
   - UTI

Question 4

What guideline is used in cases of preterm delivery?

Answer 4

NICE guideline NG25 Preterm Labour and Birth 2015

Question 5

List the risk factors for preterm delivery

Answer 5

1. Previous history
2. Lower SE class
3. Extremes of maternal age
4. Short-inter pregnancy interval
5. Maternal disease e.g. DM, rheumatic fever
6. Pregnancy complications - PET, IUGR
7. Male fetal gender
8. STIs
9. Vaginal infection
10. Previous cervical surgery
11. Multiple pregnancy
12. Uterine abnormalities and fibroids, UTI
13. Polyhydramnios
14. APH
15. Congenital fetal abnormalities

Question 6

How can preterm labour be prevented?

Answer 6

1. Cervix = cervical cerclage
2. Progesterone supplementation = suppositories from early pregnancy reduce the risk of preterm labour in those who are high risk (disputed efficacy - OPPTIMUM trial)

Question 7

What is cervical cerclage?

Answer 7

Cervical cerclage is the insertion of one or more sutures in the cervix to strengthen it and keep it closed

Question 8

What are the different types of cervical cerclage?

Answer 8

1. McDonald’s cerclage - placed using permanent suture
2. Shiradkor technique
3. Abdominal cerclage

Question 9

When is cervical cerclage used?

Answer 9

1. Elective at 12-24wks if high risk
2. Cervix scanned regularly and only sutured if significant shortening
3. ‘Rescue suture’

Question 10

What are the indications for prophylactic vaginal progesterone or prophylactic cervical cerclage?

Answer 10

1. History of spontaneous pre-term birth or mid-trimester loss between 16+0 and 34+0 weeks of pregnancy

AND

2. TVUS carried out between 16+0 and 24+0 weeks of pregnancy revealing a cervical length <25mm

Question 11

What are the indications for prophylactic vaginal progesterone?

Answer 11

1. No history of spontaneous preterm birth or mid-trimester loss in whom TVU has been carried out between 16-24wks showing cervical length <25mm

Question 12

What are the indications for prophylactic cervical cerclage?

Answer 12

TVUS carried out between 16-24wks revealing cervical length <25mm and who have either of following:

1. PPROM in previous pregnancy
2. History of cervical trauma

Question 13

What investigations are carried out to determine if a woman is at risk of preterm delivery?

Answer 13

1. Cervical length:
   - TVUS
   - Sensitive and specific
   - If cervical length <15mm at 23wks, 85% chance of delivery before 28wks

Question 14

List the clinical features of preterm labour

Answer 14

1. History:
   - Painful contractions
   - Dull suprapubic ache - painless cervical dilatation
   - APH and SROM
2. Exam:
   - Fever
   - Check lie and presentation
   - VE = dilatation and effacement

Question 15

What investigations should be done if preterm labour is suspected?

Answer 15

1. Fetal wellbeing:
   - CTG
   - US
2. Likelihood of delivery:
   - Fetal fibronectin assay (test in swab of secretions from ccervix; negative result [<50ng/ml] = delivery unlikely)
   - TVS (cervical length >15mm = delivery unlikely)
3. Check for infection:
   - High vaginal swab (HVS)
   - Bloods - WCC, CRP

Question 16

How do we manage a woman in preterm labour?

Answer 16

1. Fetal lung maturity:
   - Steroids at 24-37wks
2. Fetal neuroprotection:
   - Magnesium sulphate <32wks (reduces risk of CP)
   - HSE CPG 2012 Antenatal Magnesium Sulphate for Fetal Neuroprotection
3. Tocolysis - can delay delivery up to 7 days in some cases (NOT associated with reduction in mortality or perinatal morbidity - Greentop)

Question 17

What tocolytic agents can we use in preterm labour?

Answer 17

1. Nifedipine - Calcium channel blocker- blocks calcium channels in the myometrium, interrupting contraction
2. Atosiban - oxytocin receptor antagonist

Question 18

What patients benefit from tocolytic treatment?

Answer 18

1. Very preterm labour
2. Those who need transfer to another hospital
3. Allow time for steroids to work

Question 19

What should be done in the presence of chorioamnionitis?

Answer 19

1. IV abx

2. Immediate delivery

Question 20

Define preterm prelabour rupture of membranes (PPROM)

Answer 20

ROM <37wks

Question 21

What is the incidence of PPROM?

Answer 21

2% of pregnancies but accounts for 40% of preterm deliveries

Question 22

List the complications of PPROM

Answer 22

1. Preterm delivery - follows within 48hrs in >50%
2. Infection - fetus or placenta or cord
3. Prolapse of umbilical cord - rare
4. Absence of liquor - can result in pulmonary hypoplasia and postural deformities

Question 23

What is the history like in PPROM?

Answer 23

Gush of clear liquid, followed by further leaking

Question 24

What will be seen on examination in PPROM?

Answer 24

1. Check lie and presentation
2. Speculum - pool of fluid in posterior fornix
3. VE - best avoided, but can be done to exclude cord prolapse if presentation is not cephalic
4. Chorioamnionitis - characterised by contractions or abdominal pain, fever, tachycardia, uterine tenderness and coloured or offensive liquor

Question 25

What investigations should be done if PPROM is suspected?

Answer 25

1. Confirm diagnosis: - Nitazine test (pH) - Fern test 2. US: - reduced liquor volume 3. Check for infection: - HVS - CRP - FBC - Amniocentesis with gram staining and culture 4. Fetal wellbeing: - CTG

Question 26

How is PPROM managed?

Answer 26

- Balance risk of preterm delivery vs risk of infection - Steroids - Close monitoring for signs of infection - If >34wks, for IOL - Antibiotics

Question 27

How can infection be prevented in PPROM?

Answer 27

- Prophylactic use of erythromycin for 10days | Co-amoxiclav contraindicated, as increased neonatal risk of NEC