Preterm Labour

Question 1

2 key determinants of fetal outcomes in preterm babies?

Answer 1

• birthweight
  
  • average = 3.5kg at term
  • SGA or LGA
• gestational length

Question 2

Care of the preterm infant?

Answer 2

• Pink
  
  • well oxygenated ($4000 to ventilate in NICU)
• Sweet
  
  • normoglycemia
• Warm
  
  • prevent hypothermia

Question 3

Reasons/Causes for delivery <34 weeks?

Answer 3

• Major Obstetric indications
  
  • pre-eclampsia
  • FGR
• Infection (cause or consequence)
• multiple pregnancy
• APH
• preterm labour
• PROM

Question 4

What things can you do to stop preterm labour?

Answer 4

• most prophylactic methods don’t work:
  
  • socioeconomic strategies
  • education
  • cervical cerclage
  • bed rest (not proven)
  • prophylactic tocolysis (never shown helpful) - increasing Braxton Hicks doesn’t increase preterm risk
  • uterine activity monitoring
  • control vaginal infections/Obs problems
• TLC - trial participation decreases incidence.

Question 5

How can you predict preterm labour?

Answer 5

• uterine activity monitoring
• serial cervical assessment (for length and ilation)
  
  • shortening (short cervic = 25mm) dilating will give indicators of impending preterm
  • possible assess length
    
    • US - between 20-28weeks. Gestational age asc.
    • cervical effacement (T, Y, V, U) - internal towards external dilation. Dynamic, not always closed.
  • usually approx 3.5cm length + few mm width
  • cervical insufficiency - suture cervix, progesterone pessaries
• cervicovaginal microbiology
• cervicovaginal biochemistry
  
  • foetal fibronectin (ECM protein secreted by trophoblast)
  • bedside test - qualitative (look for line), quantitative now ELIZA.
    
    • under 200 be reassuring.
  • uterine activity - disrupts attachment - identifiable in vaginal fornices.
  • not there between 20-35weeks - detect = preterm
  • high false positives, but good negative predictive value. No Labour next two weeks.

Question 6

How do you prepare the fetus for preterm delivery?

Answer 6

• Lungs
  
  • approx 48 hr administration of corticosteroids induces surfactant production.
    
    • betamethasone
    • dexamethasone
  • delayed labour <32 weeks better
• Neuroprotection
  
  • Magnesium sulfate - improve neuro outcomes.
    
    • <30weeks gestation as close to 4hrs before birth
  • regardless of number of fetuses, reasons for preterm birth, number of maternal parity, mode of birth.

Question 7

What is PROM? What causes it?

Answer 7

• premature rupture of the membrane
• causes:
  
  • idipathic
  • APH
  • congenital membrane weakness
  • congenital membrane weakness
  • uterine anomaly
  • genital tract infection.

Question 8

What are some toxolytic agents?

Answer 8

whether they work is not clear

• beta-adrenergics (SE profile poor, only in acute)
  
  • contraindicated in gestation >32-34weeks, <20-22weeks, pre-eclampsia, FGR, ROM, etc…
• PG synthesis inhibitors (indomethacin) -
  
  • fetal effects (oligohydramnios -renal flow, close ductus prematurely)
• CCB - nifedipine - drug of choice. Can have maternal Hypotension.
• Magnesium sulfate - not really used.

Question 9

What is the management of PROM?

Answer 9

• Diagnosis:
  
  • small for dates uterus due to oligohydramnios
  • observed vaginal fluid loss (continues to trickle)
  • alkaline pH -
  • characteristic odour. (sensitive smell)
  • biochemical markers (e.g. fibronectin)
    
    • amnisure - protein marker (PPANG)
• *US** - pooling of straw fluid in posterior fornix, fluid around baby (anhydramnios)
  
  • ferning test (collect - dry on slide) - old-fashioned.
  • pyridium test - colours urine orange.

DDx:

* leukorrhoea (oestrogen imbalance causing white d/c)
* stress incontinence * Ix:
* CTG - regular declerations
* vitals (spontaneous labour in 7 days) - infection risk, outpatient own monitoring.
* speculum exam
* high vaginal swab (infection screen) - fortnightly
* US
* FBE
* CRP - not useful for infection, predictive marker for first presents with ROM. * Mg:
* tocolytic = short term burst to allow steroids
* ABx - erythromycin prefered (chorioamnionitis)
    * just treating improves outcome.
    * CP rate with use of antibiotics? (inflam mediators holding them in uterus for longer?)
* corticosteroids
* amnioinfusion - artificial fluid never shown beneficial.
* oxytocics? (why?) - syntocinon/PGs

Question 10

Complications of PROM?

Answer 10

• infection
• preterm labour
• Maternal:
  
  • hospitalisation
  • anxiety
  • genital tract sepsis
  • CS
• Fetal
  
  • pulmonary hypoplasia - pressure of uterus on developing lungs
  • limb contractures
  • prematurity
  • umbilical cord compression

Question 11

Preterm Labour Management Acronym?

Answer 11

STATIN:

• Statin
• Transfer + admission
• Antibiotics
• Tocolysis
• Intrapartum care
• Neuroprotection <30 (neonatal review)