Labour Flashcards
What is the latent phase of labour?
A period of time, not necessarily continuous, when there are painful contractions, and some cervical change, including cervical effacement and dilatation up to 4cm
What is established labour?
Regular painful contractions, and progressive cervical dilatation from 4cm
What are the stages of established labour?
1st stage: From onset of established labour (4cm) to full dilatation of the cervix (10cm)
2nd stage: From full dilatation to birth of the baby
3rd stage: From delivery of the baby to expulsion of the placenta and membranes
What is the passive second stage of labour?
The period between full dilatation of the cervix and onset of involuntary expulsive contractions
What is the active second stage of labour?
Expulsive contractions or active maternal effort with a finding of full dilatation of the cervix
How can the third stage of labour be managed?
Physiological management - no routine use of uterotonic drugs, clamping of cord only when pulsations stop, delivery of placenta by maternal effort, prolonged if > 60 mins
Active management - reduces risk of haemorrhage and shortens duration of 3rd stage. Uterotonic drugs e.g. syntometrine given, clamp and cut cord after 1 min has passed, controlled cord traction. Prolonged if > 30 mins
After how long is the active 2nd stage of labour said to be delayed in a nulliparous woman?
> 2 hours
After how long is the active 2nd stage of labour said to be delayed in a multiparous woman?
> 1 hour
How is the fetus monitored during labour in low risk women?
Intermittent auscultation of the fetal heart using Doppler or Pinard stethoscope
How is the fetus monitored during labour in high risk women?
Continuous fetal monitoring using cardiotocograph (CTG)
What position does the fetal head engage into the pelvis during descent?
Left or right occipito-anterior position
What are the mechanisms of labour from engagement to delivery of the shoulders (how the fetus moves through the pelvis)?
Engagement - when largest diameter of head descends into maternal pelvis. Fetal head is 3/5ths palpable of less
Flexion - Cervical flexion when fetal head contacts pelvic floor (assists passage through pelvis)
Internal rotation - Fetal head rotates 90o from L or R occipital-transverse position to occipito-anterior position to lie under the suprapubic arch
Crowning - when widest part of the head successfully negotiates the narrowest part of the bony pelvis
Extension - Occiput slips beneath suprapubic arch allowing the head to extend, head is delivered
Restitution - head externally rotates, shoulders reach pelvic floor and rotate from transverse to AP position
Delivery of shoulders - Downward traction by midwife to assist delivery of anterior shoulder followed by upward traction to deliver posterior shoulder
What is used to monitor progress of labour and what does it chart?
Partogram - charts cervical dilation and descent of head, frequency of contractions, fetal heart rate, liquor colour, maternal obs (BP, HR, temp), drugs and fluids, use of oxytocin, unrinalysis
What is the criterion for defining delay in 1st stage of labour?
Primigravida: cervical dilatation < 2cm in 4 hours
Multigravida: cervical dilatation < 2cm in 4 hours or a slowing down in the rate of progress
What are the indications for assisted vaginal delivery?
Slow progress in 2nd stage of labour, maternal exhaustion, avoiding raised ICP or BP, presumed fetal compromise
What methods exist for assisted vaginal deliver?
Vacuum extraction (Ventouse), Traction forceps, Rotational forceps
What are some fetal complications of instrumental delivery?
Cephalhaematoma, facial bruising, facial nerve palsy, retinal haemorrhage, hyperbilirubinaemia
What are some maternal complications of instrumental delivery?
Cervical laceration, vaginal laceration, haematoma, perineal tear, psychological trauma
What are the pre-requisites for instrumental delivery?
F - Fully dilated cervix O - One fifth or nil palpable abdominally R - Ruptured membranes C - Contractions present E - Empty bladder P - Presentation and position known S - Satisfactory analgesia
What are absolute contraindications to instrumental delivery?
Malpresentation, unengaged fetal head, cephalopelvic disproportion, fetal clotting disorder.
If < 34 weeks - can use forceps but not Ventouse
In what circumstances should instrumental delivery be abandoned?
Difficulty applying instrument, no descent, delivery not imminent after 3 pulls, 15 mins has elapsed
What are the indications for induction of labour?
Going post-term (42 weeks), IUGR, prelabour rupture of membranes, APH, maternal HTN or diabetes, poor obstetric Hx, intrauterine death, maternal request.
What should be offered to women before formal induction of labour in an attempt to aid labour initiation?
Membrane sweeping a.k.a. stretch and sweep
Finger inserted through cervix - causes localised release of prostaglandins
What scoring system is used to assess the cervix and whether induction of labour will be needed?
Bishop score
What factors are assessed when calculating the Bishop score?
Cervical dilation Length of cervix (effacement) Station Consistency of cervix (firm/medium/soft) Position of cervix (posterior/central/anterior)
What are the progressive stages of labour induction once membrane sweeping has been offered?
- Up to 3 doses of prostaglandin gel inserted into posterior fornix
- Artificial rupture of membranes - causes local prostaglandin release
- Syntocinon iv infusion
Why should a vaginal examination not be performed in Preterm Premature Rupture of Membranes (PPROM)?
Risk of introducing ascending infection
How should PPROM be managed?
Erythromycin 250mg QDS for 10 days (prevent/treat chorioamnionitis)
and
Steroids if between 24 - 34+6 weeks to accelerate fetal lung development.
Outpatient monitoring of growth, maternal temp and CRP until 34 weeks at which point, induce labour.
What are the management steps for slow progress of labour (<0.5cm per hour in 4 hours)?
- Artificial rupture of membranes
- Syntocinon infusion
- C-section
