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13.06.01 Normal labour

Definition
  • Products of conception expelled by the mother
  • Progressive dilatation and effacement of the cervix
  • Painful, regular contractions

Stages of labour
  • Stages
    • First = Onset of true uterine contractions to full dilatation of cervix
    • Second = Full dilatation and rupture of membrane to delivery of foetus
    • Third = Complete expulsion of foetus to complete expulsion of placenta and membranes
  • Latent/active
    • Latent = <4 cm dilated, irregular contractions
    • Active = >4 cm dilated, rapid further dilatation, fast/continuous contractions

Assessment of cervix
  • Dilatation
  • Effacement
  • Consistency
  • Position of foetus
  • Presenting part

Post-partum haemorrhage
  • Primary (<24 hrs)
    • Atonic uterus
    • Retained placental part
    • Tears
  • Secondary (>24 hrs - 6 weeks)
    • RPOC
    • Infection
    • Endometritis

Bishop score

  • Interpretation
    • > 8 => Likely to achieve a successful vaginal birth
    • < 7 => Cervical ripening method (prostaglandins)


Indications for induction
  • Post-term
  • Pre-eclampsia
  • Obstructive cholestasis (risk of stillbirth)
  • Diabetes (big baby)

Head position

  • OA = Best
  • ROA/LOA = Fine, but a bit slower as it has to rotate
  • Transverse get stuck
  • OP get stuck (face presentation)

CTG interpretation



Fetal blood sampling
  • pH < 7.2 => Urgent delivery
  • pH 7.2 - 7.25 => Repeat in 30 mins
  • pH 7.25 - 7.3 => Repeat in 60 mins

Notes
  • Braxton-Hicks contractions: Irregular, occur throughout pregnancy, start at first trimester
  • Power, Passage, Passenger
  • Uterine muscle doesn't ever relax - just progressively contracts
  • Oxytoxin to encourage the placenta out (if >30 mins)
  • ERCP = Evacuation of retained products of conception
  • Station is measured relative to ischial spines (zero = head at spines)
  • STAN = ST analysis/T:QRS ratio = Measure of chronic oxygen deprivation
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