Labour Flashcards
What is labour?
The process whereby the fetus and placenta expelled from the uterus, which normally occurs between 37 and 42 weeks.
When is labour diagnosed?
When painful uterine contractions accompany dilatation and effacement of the cervix
What occurs in the first stage of labour?
The cervix opens to full dilatation to allow the head to pass through
When is the second stage of labour?
Between full dilution and the delivery of the fetus
What is the third stage of labour?
From delivery of the fetus to delivery of the placenta
What are the three mechanical factors of labour?
[1] The degree of force expelling the fetus (the powers)
[2] The dimensions of the pelvis and the resistance of soft tissues (the passage)
[3] The diameters of the fetal head (the passenger)
How often does the uterus contract during labour?
For 45-60 seconds about every 2-3 minutes
What do contractions do?
Pull the cervix ip (effacement) and cause dilation, aided by the pressure of the head as the uterus pushes the head down into the pelvis.
When is poor uterine activity common?
In nulliparous women and in induced labour
How is the level of descent in the uterus measured?
Using the ischial spines as station 0 and how many cm above or below, if it is 2cm below the spines, it is station +2, if it is 2cm above the spines it is station-2.
What factors determine how easily the head fits through the pelvic diameters?
The attitude (extension/flexion); the position (rotation) and the size of the head
What attitude is ideal for labour?
Maximal flexion, keeping the head bowed, this is called vertex presentation.
Why do you not want the attitude to be extension in labour?
A small degree of extension results in a larger diameter.
What is a brow presentations?
Extension of the head at 90 degrees
What is a face presentation
120 degree extension of the head, with the face looking parallel and away from the body.
What is the position of the head?
The degree of rotation of the head on the neck.
What should happen to the position of the head during labour?
The head must normally rotate 90 degrees during labour to fit through. It should be delivered with the occiput anterior.
What is moulding?
The head can be compressed in the pelvis because the sutures allow the bones to compress together and even overlap slightly
What are the positions that the head can be in?
Occipito-transverse (bad, needs assistance)
Occipito-posterior (more difficult to deliver)
Occipito-anterior (good)
What does prostaglandin production do during pregnancy?
It reduces cervical resistance and increases the release of oxytocin from the posterior pituitary, which aids stimulation of contractions
What is effacement?
When the normal tubular cervix is drawn up into the lower segment until it is flat.
What is the ‘show’ that often accompanies effacement?
Pink/white mucus plug from the cervix and/or rupture of the membranes, causing release of liquor.
What is the latent phase of the first stage of labour?
Where the cervix usually dilates slowly for the first 3cm and may take several hours
What is the active phase of the first stage of labour?
Average cervical dilatation is at the rate of 1cm/h in nulliparous women and about 2cm/h in multiparous women. The active first stage should not normally last more than 12h
What happens to the fetus during the second stage of labour?
Descent, flexion and rotation are completed and followed by extension as the head delivers.
What is the passive stage of the second stage of labour?
It is from full dilatation until the had reaches the pelvic floor and the woman experiences the desire to push.
How long does the passive stage of the second stage of labour last?
It can last a few minutes, but can be much longer
What is the active stage of the second stage of labour?
When the mother is pushing.
What causes the urge for the mother to push?
The pressure of the head on the pelvic floor produces an irresistible desire to bear down, although epidural analgesia may prevent this.
How long after the active stage of the second stage of labour is the baby normally delivered?
On average after 40 minutes (nulliparous) or 20 minutes (multiparous). This can be much quicker but if it is over an hour spontaneous delivery is unlikely
How long does the third stage of labour usually last for?
15 minutes
Why does the mother stop bleeding after delivery?
Uterine muscle fires contract to compress the blood vessels formerly supplying the placenta, which shears away from the uterine wall.
What is a first degree perineal tear?
Involves minor damage to the fourchette.