Normal Labour & Delivery

Question 1

Powers, passages and passenger

Answer 1

• Powers = uterus
  
  • Labour contractions
• Passages = pelvis
  
  • Pelvis - inlet, outlet
  • Cervix - effacement, dilatation
• Passenger
  
  • Fetus - lie, presentation
  • Fetal head - position (degree of rotation of babies head), station (relation of vertex of babies head in relation to iliac spines), engagement (how many 5ths of the babies head are inside the pelvis), caput (physiological swelling of head of baby), moulding (degree of plate overlap)

Question 2

Definitions

Answer 2

• Labout - the presence of contractions of sufficient strengthto cause cervical effacement and dliatation
• Contractions - tightening and shortening of the uterine muscle (optimally 3-4 in 10 minutes lasting 40-80 seconds)
• Effacement - shortening of the cervical canal from 3cm to fully effaced
• Cervical ripening - softening of cervix, assessed using Bishop’s Score which includes dilatation, length of cervix, station of presenting part, consistency and position)
• Dilatation - upper segment shortens by muscle contraction to expel the fetus
• Lie - relation of fetal axis to mother (longitudinal, transverse, oblique)
• Presentation - part of fetus closest to birth canal (cephalic, breech, shoulder)
• Position - relation of presenting part to maternal pelvis (left occipito-anterior, direct occipito-anterior)
• Station - relation (in cm) of the presenting part to the ischial spines
• Engagement - descent of the widest diameter of the presenting part below pelvic inlet

Question 3

Fetal head anatomy

Answer 3

Question 4

Stages of labour

Answer 4

• 1st stage (latent phase) - onset of effective contractions until 3cm dilated and fully effaced
• 1st stage (active phase) - end of latent phase until full dilatation, 8-18 hours for latent and active together
• 2nd stage - full dilatation until delivery, within 3 hours of start of active stage
• 3rd stage - delivery of baby until delivery of the placenta within 1 hour

Question 5

Management of normal delivery

Answer 5

• 1st and 2nd stages
  
  • Maternal recordings (contractions, BP, temperature)
  • Assess progress (abdominal and vaginal examination every 2-4 hours)
  • Encourage to push in 2nd stage
  • Restricted use of episiotomy
• 3rd stage
  
  • Watch for signs of PPH
  • Can give oytocin and controlled cord traction

Question 6

Induction of labour

Answer 6

• Artificial initiation of contractions
• Indicated if:
  
  • Maternal health problems
  • Obstetric complications (PIH, IUGR, prolonged pregnancy)
  • Fetal conditions (anomaly requiring treatment)
• Methods:
  
  • Membrane sweep (releases local PGs)
  • Vaginal PGE2 (prostin)
  • ARM
  • Oxytocin

Question 7

Analgesia in labour

Answer 7

• Entonox (best before pain starts)
• Systemic opiates (avoid if delivery imminent)
• Epidurals
• Spinals (for instrumental delivery)
• General anaesthesia (good if all else fails or in emergencies)
• Local analgesia