Labour Flashcards
Define Labour.
Products of conception expelled from uterus >24 weeks gestation.
Before how many weeks gestation is labour considered pre-term?
Before 37 weeks
What is the average length of labour for primiparous and parous women?
primiparous - 10 hours (unlikely to exceed 18 hours)
parous - 5.5 hours (unlikely to exceed 12 hours)
Describe the 1st stage of labour.
Onset of regular contractions
Cervical changes
Lasts until full dilatation of cervix and no longer palpable
The 1st stage of labour is split into the early latent phase and the active phase. Describe the cervical changes that occur in each.
Early latent phase - cervix becomes effaced, shortens in length and dilates to 4cm
Active phase - cervix fully dilates to 10cm
Describe the 2nd stage of labour.
From full cervical dilatation to delivery of foetus
The 2nd stage of labour is split into passive and active stages. Describe each.
Passive - full dilatation of cervix prior to or in absence of involuntary expulsive contractions
Active - baby is visible/ persistent involuntary expulsive contractions/ other signs of full cervical dilatation/ active maternal effort in absence of involuntary expulsive contractions
When is prolonged 2nd stage abour diagnosed in nulliparious women?
At 2 hours
When is prolonged 2nd stage labour diagnosed in multiparious women?
At 1 hour
What is the first-line management of prolonged labour?
Refer to obstetric reg unless birth is imminent
List 4 complications of prolonged labour.
Foetal distress
PPH
Pelvic floor dysfunction
Fistulae
Describe the 3rd stage of labour.
Time between delivery of foetus and delivery of placenta and membranes
Occurs 10-15 mins post foetal delivery and can last up to 30 mins
Describe physiological management of the 3rd stage of labour.
No drugs, cord not clamped until pulsations ceased
Placenta delivered by maternal effort
Describe active management of the 3rd stage of labour.
Use of uterotonic drugs (oxytocin or syntometrine) with delivery of anterior shoulder or immediately after birth or before cord stops pulsating
Bladder catheterisation
Deferred cord clamping and cutting
Controlled cord traction after sings of placental separation
Outline the signs of placental separation from membranes.
The uterus contracts, hardens and rises
Umbilical cord lengthens permanently
There’s a gush of blood variable in amount
Placenta and membranes appears at introitus.
Outline the pros and cons of active management of the 3rd stage of labour.
Pro - shortens length of 3rd stage
cons - increase risk of N&V, haemorrhage and blood transfusion
When is a change from physiological management of 3rd stage labour to active management indicated?
Excessive bleeding of haemorrhage occurs
Failure to deliver the placenta within one hour
The patient’s desire to shorten the third stage.
Describe 3 clinical signs of the onset of labour.
Regular, painful contractions that increase in duration and frequency
Passage of blood stained mucous from cervix
Rupture of membranes
What is the definition of prelabour rupture of membranes?
If the period between rupture of membranes to painful contractions is >4hours.
Called premature rupture of membranes if occurs before full-term gestation.
Describe hormonal changes that occur to initiate labour.
progesterone decreases
oestrogen and oxytocin increase thus increasing prostaglandin production
CRH is also thought to be involved - increases oestrogen and prostaglandin synthesis and reduces progesterone
How does oxytocin act to initiate labour?
released from posterior pituitary
acts on decidual tissue to promote prostagladin release
Initiates and sustains contractions
Also synthesised directly in decidual and extraembryonic tissue and placental tissue
oxytocin receptors in myometrial and decidual tissues increases towards end of pregnancy to increase uterine contractility
State another 2 hormones that influence uterine myocytes.
relaxin
activin A
(influence cAMP production causing relaxation of myometrial cells. Relaxin also helps soften pelvic ligaments and the pubic symphysis so allow room for baby to exit)
Describe 3 changes in the cervix towards term gestation/in labour.
Decreased collagen
Increased hyaluronic acid (softens and stretches the cervix by decreasing affinity for fibronectin and collagen and increasing affinity for water)
Progressive uterine contractions causes effacement and dilatation of cervix
State the 7 stages of labour.
Engagement Descent Flexion Internal rotation Extension External rotation (restitution) Expulsion
How is engagement assessed in the 1st stage of labour.
Assessing how much of the foetal head can be felt in the abdomen, this is done in 5ths. i.e. if all of the head can be felt in the abdomen - it is 5/5 parts palpable. If no head can be felt it is 0/5 parts palpable.
List 8 possible causes of abnormal labour.
Malpresentation (non-vertex)
Malposition (occipitoposterior, occipitotrasnverse)
Preterm labour <37 weeks
Post-term labour >42 weeks
Too painful - requires anaesthestic input
Too quick (<2 hours) - hyperstimulation, precipitate labour
Too long - failure to progress
Foetal distress (hypoxia, sepsis)
Use the 3 Ps of labour to suggest reasons for failure to progress.
Powers - inadequate contractions
Passage - trauma, shape, cephalopelvic disproportion
Passenger - big baby, malposition
What are the possible complications of obstructed labour?
Sepsis - ascending genitourinary tract infection
PPH
fistula formation
Foetal asphyxia
Neonatal sepsis
Uterine rupture - increased risk if previous scar
Obstructed AKI
How is progression of labour assessed?
Vaginal examination every 4 hours to assess cervical dilatation, descent of presenting part and signs of obstruction (moulding, caput, anuria, haematuria, vulval oedema)
How is failure to progress defined?
<2cm cervical dilatation in 4 hours