Women's Health : Labour + Parturition Flashcards
How many stages is labour divided into?
3 stages
What defines the onset of the First Stage of Labour?
Progressive contractions and cervical changes
What are the 2 stages of First Stage of Labour?
Latent and Active first stage
What is involved in the Latent first stage?
Effacement (thinning) of cervix and dilatation to 3cm
What is involved in the Active first stage?
Dilatation from 3 - 10cm (i.e. fully dilated)
What occurs during the Second stage of Labour?
From full dilation to delivery of the baby
What are the two phases of the Second stage?
Passive and Active second stage
Passive second stage
head descends down pelvis
Active second stage
mother bears down
What happens in the Third stage of Labour?
Delivery of placenta and membranes
How long should the Third stage take?
Within 30 minutes of delivery of the baby
What are the management options for the Third stage?
Can be physiological (i.e. no intervention) or actively managed (oxytocin injection after delivery of anterior shoulder).
What coincides with the onset of labor?
passage of the operculum (mucus plug) and spontaneous rupture of membranes (SROM) should coincide with the onset of labour but are not defining features
What hormonal changes are triggered by the fetus to initiate labor?
The fetus triggers an increase in maternal oestrogen and a decrease in progesterone, along with factors like uterine stretch, cortisol, and the Ferguson reflex.
What is the result of increased maternal oestrogen and decreased progesterone in labor initiation?
It leads to the expression of Contraction-Associated Proteins (CAPs) and increased production of oxytocin and prostaglandins.
What is the role of Contraction-Associated Proteins (CAPs) in labor?
CAPs increase the expression of oxytocin receptors, prostaglandin receptors, gap junction proteins, and ion channels to facilitate uterine contractions.
Why is the increase in both agonists (like oxytocin) and receptors important in labor?
It prepares the uterus for effective contractions by ensuring that both the molecules initiating contractions and their receptors are present in high amounts.
How does the uterine muscle contract during labor?
The uterine muscle contracts due to the spread of action potentials, which open L-type calcium channels, increasing intracellular calcium.
What happens when intracellular calcium levels increase in uterine muscle cells?
The increase in calcium initiates actin-myosin sarcomere contraction, leading to muscle contraction in the uterus.
How is the duration of a uterine contraction determined?
The duration of a contraction is directly related to intracellular calcium levels; the longer calcium levels remain high, the longer the contraction lasts.
Which substances increase calcium-channel opening in the uterine muscle?
Prostaglandin F2-alpha and oestrogen increase calcium-channel opening, promoting uterine contractions.
What is myometrial activation?
Uterine contractions synchronized and coordinated at term
What triggers the endocrine cascade for labor?
Foetus
What hormones increase due to the endocrine cascade?
Maternal oestrogen
What hormone decreases due to the endocrine cascade?
Progesterone
What are some contributing factors to labor onset?
Uterine stretch, cortisol, Ferguson reflex
What proteins are expressed in response to labor initiation?
CAPs
What increases alongside CAP expression?
Oxytocin and prostaglandins
What do CAPs increase the expression of?
Oxytocin receptors
What do gap junction proteins facilitate?
Contractions
What initiates uterine muscle contraction?
Action potential spread
What increases intracellular calcium in uterine contractions?
L-type calcium channels
What hormones increase calcium-channel opening?
Prostaglandin F2-alpha and oestrogen
What are the 7 stages of labour?
- Descent 2. Flexion 3. Internal Rotation 4. Extension 5. Resistituion 6. External Rotation 7. Delivery of Shoulders
What is the first stage of the second stage of labour?
Descent
What happens during the “Descent” stage of labour?
- the baby’s head (providing it is in cephalic presentation) descends deeper into the pelvis until it is no longer palpable on abdominal examination.
What happens during the “Flexion” stage of labour?
- the baby’s head flexes (chin to chest) to give the narrowest (suboccipitobregmatic) diameter.
What happens during the “Internal Rotation” stage of labour?
baby’s occiput rotates anteriorly from the lateral position to give the normal occipito-anterior position.
What happens during the “Extension” stage of labour?
Baby’s occiput contacts pubic rami - it then extends and crowns
What happens during the “Restitution” stage of labour?
- baby’s occiput re-aligns with its shoulders, which lie in between the anterior-posterior and lateral positions
What happens during the “External Rotation” stage of labour?
baby’s shoulders rotate into anterior-posterior position (i.e. perpendicular to mother’s). At this point, the baby’s head is delivered - it is aligned with its shoulders, so the face looks laterally at the mother’s thigh
How are the shoulders delivered?
the anterior shoulder is delivered first from beneath the pubic ramus; the head is then gently lifted anteriorly to deliver the posterior shoulder. The rest of the baby’s body rapidly follows.
What is included in the initial assessment during monitoring in labour?
Take history, assess risk factors, assess pain
Which vital signs are monitored during initial assessment?
Pulse, blood pressure, respiratory rate
What does abdominal palpation determine?
Lie, presentation, engagement, contraction strength
What does a vaginal examination determine?
Station, position, cervical effacement and dilatation, presence or absence of membranes, caput or cranial moulding
What is recorded on a partogram?
progression of Labour, foetal, maternal wellbeing
What progress measurements are recorded?
Cervical dilatation, descent, contractions (frequency and duration)
How is foetal wellbeing monitored?
Heart rate, amniotic fluid (liqour)
What maternal wellbeing measurements are recorded?
Pulse, blood pressure, temperature, urinalysis
Heart rate can be monitored by …..
intermittent auscultation with a Doppler probe (in low risk deliveries) or continuously with a cardiotocograph (CTG, in higher risk deliveries)
How is heart rate monitored in higher risk deliveries?
Continuous cardiotocograph (CTG)
Normal CTG
No non-reassuring features
Suspicious CTG
One non-reassuring
Pathological CTG
Two non-reassuring or one abnormal
Reassuring features of the CTG : baseline HR
110-160 bpm
Reassuring features of the CTG : decelerations
(drops of 15 bpm for 15s): absent
Reassuring features of the CTG : accelerations
(increases of 15 bpm for 15s): present
Reassuring features of the CTG : Baseline variability
5-25 bpm
Non-reassuring features of the CTG : Baseline Rate
100-109 / +20 from start of labour
Non-reassuring features of the CTG : Accelerations
Absent
Non-reassuring features of the CTG : Decelerations
Repetitive variable for <30 mins / variable for <30 mins / repetitive late for 30 mins
Non-reassuring features of the CTG : Variability
<5 for 30-50 mins / >25 for <10 mins
Abnormal features of the CTG : Baseline Rate
<100 / >160
Abnormal features of the CTG : Accelerations
Absent
Abnormal features of the CTG : Decelerations
Repetitive variable with concerning characteristics >30 mins / repetitive late >30 mins / 3 min bradycardia
Abnormal features of the CTG : Variability
<5 for 50 mins / >25 for >10 mins / sinusoidal pattern
Non-pharmacological analgesia methods in labour
Breathing, relaxation, birthing pool
Non-regional analgesia methods in labour
: Entonox (‘gas and air’ - 50:50 mix of nitrous oxide and oxygen), intramuscular opioids e.g. diamorphine or morphine
Regional analgesia methods in labour
: Epidural - local anaesthetic e.g. bupivacaine combined with fentanyl bolused into L3-4 epidural space, where it acts upon nerve roots to provide analgesia. N.B. a ‘passive hour’ without active pushing upon full dilatation is required.
Entonox composition
50:50 nitrous oxide and oxygen (gas and air)
Labour can be induced artificially, and is usually done so for what indications?
- Prolonged pregnancy >41 weeks 2. Preterm prelabour rupture of membranes (usually offered at 37+0) 3. Term prelabour rupture of membranes (offer 24hrs expectant management as well) 4. Maternal request 5. Maternal health issues e.g. pre-eclampsia, obstetric cholestasis 6. Intrauterine foetal death (IUFD)
At what gestation is induction of labour usually offered for prelabour rupture of membranes?
37+0
What is recommended for term prelabour rupture of membranes?
24 hours expectant management
What are the methods for inducing labour?
Membrane Sweep
Describe the membrane sweep
finger passed through cervix to separate part of the chorionic membrane from the decidua; offered from 39+0.
Method for inducing labour if Bishop Score < 6
prostaglandin E2 pessary (dinoprostone) or osmotic dilator
Method for inducing labour if Bishop Score > 6
amniotomy (artificial rupture of membranes) +/- oxytocin infusion.
