Preterm Labour Flashcards
What is preterm labour
Onset of labour prior to 37 week gestation
What are sub classification of pre term Labou?
Very preterm <32
Extremely preterm <28
What is PTL correlated to?
Higher morbidity and mortality
What are common short term issues in pre term babies
- Respiratory distress syndrome
- Intraventricular haemorrhage > neurological deficit
- Paraventricular leukomalacia
- Necrotising enterocolitis
- Sepsis
- Retinopathy
What are key RF for preterm birth?
Prior preterm birth
Prior second trimester loss
Prior cervical biopsy / intervention
Why is second trimester loss important in PTL and not first trimester loss?
Because first trimester loss is likely due to genetic / chromosomal foetal abnormalities
Second trimester instead is more likely that the foetus is normal and the cervix is unable to hold it in
What are secondary RF for PTL?
- Immunological e.g. infection, vaginal microbiome
- Mechanical e.g. fibroids, multiple pregnancy (push down on baby)
- Structural (uterine abnormality)
- Social (smoking, drugs, age, BMI extremes)
What are common infections linked to PTL?
BV
UTI
Chlamydia / gonorrhoea
Why do UTIs commonly occur in pregnancy?
Due to relaxation of SM
What are examples of cervical interventio ns that trigger cervical weakness?
LLETZ Cone biopsy (NOT punch biopsy, as that is too small)
What does PTL present with?
Regular uterine contractions
Leaking amniotic fluid
PV bleed
Worsening lower back pain
What is very important to test during suspected PTL?
Take cervicovaginal fluid level of FOETAL FIBRONECTIN
fFN
What is fFN?
A glycoprotein produced by chorionic membranes as you are approaching labour
What are boundaries of ffN and what does it indicate?
fFN <50 gives a NEGATIVE result, so chance of delivering in next week is <1%
fFN >50 is POSITIVE RESULT (so admit, potential tocolysis etc.)
What are tocolytics?
Medications that delay labour for long enough to give corticosteroids and magnesium sulphate
What Is the common tocolytic given?
Nifedipine (calcium channel blocker)
Inhibits calcium influx into cells > prevents SM contraction
Why must you not give beta agonists as tocolytics
Because they have important maternal side effects e.g. pulmonary oedema
Why must you not give NSAIDS as tocolytics?
NSAIDS inhibit prostaglandins
this causes::
- premature closure of ductus arteriosus
- leads to persistent pulmonary hypertension
When are corticosteroidfs given in PTL?
24-34 week gestation
How many doses of corticosteroids must be given?
2 doses 24h apat
How long does corticosteroid benefit last fo?
2 to 7 days
What are corticosteroids to give in PTL
‘Dexamethasone
What do you need to keep in mind if giving steroids in PTL mother?
That steroids increase WCC
This means there is an increased risk of confusion if the mother is infection
What is a negative effect of giving repeated doses of steroids on the foetus?
Impact baby IQ
What other dug would you consider in PTL with PPROM?
Antibiotics
10 day course of erythromycin
How do you predict risk of preterm delivery?
Based on Past Obstetric Hx (prior PTD)
Based on cervical length measured on TVUSS (short cervix > high risk)
When would you perform a rescue cerclage?
At 16-24 weeks, if cervix is dilated (with exposed membranes) but membranes are intact and there are no contractions
Why myst you not consider rescue cerclage is membranes are ruptured?
Because infection had spread to abdomen
There is likely chorioamnionitis developing
When would you do an US indicated cerclage?
When cervix shortens <25 mm in women with history of cervical surgery / prior PTD
What is PPROM?
Ruptured membranes <37 weeks with not uterine contractions
How is delivery related to PPROM?
Most deliveries occur in next 24h
What is PPROM diagnosed qwith?
Clinical history
Pool of liquor in vagina on speculum
How do you treat PPROM?
Erythomycin 10 days
Expectant management unless evidence of chorioamniositis
What is chorioamniositis
infection of foetal membranes, usually coming from vaginal canal
What are symptoms / signs of chorioamniositis
Offensive liquor Yellow / green liquor Maternal tachycardia Temp >37.5 High CRP >40 Tender uterus, increased uterine activity CTG shows high foetal HR
What is the function of magnesium sulphate ?
Neuroprotector
Reduces risk of cerebral palsy
when do you perform foetal fibronectin
if suspecting preterm labour
and TVUSS is not available/not approprite
What. are important considerations for delivery method in PTB
C section is harder in preterm birth - increased ilkelyhood of vertical incition
