Normal Labour and Puerperium Flashcards
What is labour?
A physiological process during which the fetus membranes, umbilical cord and placenta are expelled from the uterus.
During labour, there is an interlay of 3 key factors. What are these?
Power – uterine contraction.
Passage – maternal pelvis.
Passenger – foetus.
What is the role of progesterone (in relation to labour)?
- Keeps the uterus settled.
- Prevents the formation of gap junctions.
- Hinders the contractibility of myocytes.
What is the role of oestrogen? (think ‘o’ for ooohhh that’s sore)
- Makes the uterus contract.
* Promotes prostaglandin production.
What is the role of oxytocin in relation to labour?
- Initiates and sustains contractions.
* Acts on decidual tissue to promote prostaglandin release.
Where is oxytocin synthesised (aside from in the posterior pituitary)?
Directly in decidual and extraembryonic fetal tissues and in the placenta
The number of what receptors where increases near the end of pregnancy?
Number of oxytocin receptors increases in myometrial and decidual tissues.
What causes the initiation of labour?
- There is some degree of uncertainty about this.
- Change in the oestrogen/progesterone ratio may be implicated.
- Fetal adrenals and pituitary hormones may control the timing of the onset of labour.
What is the effect of the myometrial stretch?
It increases excitability of myometrial fibres
What is the Ferguson reflex?
The neuroendocrine reflex comprising the self-sustaining cycle of uterine contractions initiated by pressure at the cervix or vaginal walls.
What has pulmonary surfactant secreted into amniotic fluid been reported to stimulate?
Prostaglandin synthesis
What does an increase in production of fetal cortisol stimulate?
An increase in maternal estriol
What does an increase in myometrial oxytocin receptors and their activation result in?
Phospholipase C activity, and subsequent increase in cytosolitic calcium and uterine contractility.
In Bishops score, Equal weight is give to each of the 5 elements. What are these?
- Position.
- Consistency.
- Effacement. (thinning of the cervix)
- Dilatation.
- Station in pelvis.
What does the Bishops score remain?
The best and simplest method available to determine if it is safe to induce labour.
What is the 1st stage of labour?
Latent phase: 3-4cms dilatation.
Active stage: 4-10cms (full dilatation).
What is the 2nd stage of labour?
Full dilatation – Delivery of baby.
What is the 3rd stage of labour?
Delivery of baby – Expulsion of placenta and membranes.
What are the uterine contractions like in the latent stage of labour?
Mild and irregular.
What happens to the cervix during the latent stage of labour?
It shortens and softens
What is the duration of the latent stage of labour like?
Variable - usually lasts a few days
When does the active stage of labour occur?
From 4cms onwards to full dilatation
SLOW DESCENT OF THE PRESENTING PART - occurs in which stage of labour?
Active stage
What happens to contractions during the active stage of labour?
They become progressively more rhythmic and stronger.
What is normal progress during the active stage of labour classified as?
1-2cm per hour.
What increase variability of progression during the active phase of labour?
Analgesia, mobility and parity.
When does the second stage of labour begin and end?
Begins with complete dilatation of the cervix (10cm).
To delivery of the baby.
When is the 2nd stage of labour considered prolonged in a nulliparous woman?
If it exceeds 3 hours if there is multiregional analgesia, or 2 hours without.
When is the 2nd stage of labour considered prolonged in a multiparous woman?
If it exceeds 2 hours with regional analgesia, or 1 hour without.
When does the third stage of labour occur?
From delivery of the baby to expulsion of the placenta and foetal membranes.
When does the 3rd stage of labour occur?
From delivery of the baby to expulsion of the placenta and foetal membranes.
How long does the 3rd stage of labour last?
Average duration 10 minutes but can be 3 minutes or longer.
What happens after 1 hour in the 3rd stage of labour?
Preparation is made for removal under GA.
What is the expected management in removal?
Spontaneous delivery of the placenta.
What is the active management after removal?
Use of oxytocic drugs and controlled cord traction is preferred for lowing risk of post-partum haemorrhage.
What does active management during the 3rd stage involve prophylactic administration of?
Syntometerine (1ml ampoule containing 500 micrograms ergometrine maleate and 5iu oxytocin)
OR
Oxytocin 10units.
Explain how cervical softening happens.
- Increase in hyaluronic acid gives increase in molecules among collagen fibres.
- The decrease in bridging among collagen fibres gives decrease in firmness of the cervix.
Explain how cervical ripening comes about.
- Decrease in collagen fibre alignment.
- Decrease in collagen fibre strength.
- Decrease in tensile strength of cervical matrix.
- Increase in cervical decorin (dermatan sulphate proteoglycan).
What causes Braxton Hick’s contractions?
Tightening of the uterine muscles.
Braxton hicks contractions are _____ contractions
FALSE
What is this tightening of the uterine muscles thought to do?
Prepare the body for birth
When do Braxton Hick’s contractions occur?
Can start 6 weeks into pregnancy, but not usually felt until the second or third trimester
What has the feeling of a true contraction been described as?
A wave
Describe the pain which occurs during true labour contractions.
Pain starts low, rises until it peaks and finally ebbs away.
If you touch a patient’s abdomen during a contraction, how will it feel?
Hard
How far apart are contractions?
About 5-10 minutes apart.
What are Braxton Hicks contractions sometimes called? Why?
‘False labour’ – because they give the woman a false sensation that she is having real contractions.
Although Braxton Hick’s contractions can thin the cervix (the opening of the uterus), what do they not do?
Induce labour
Describe Braxton Hick’s contractions.
Irregular, do not increase in frequency or intensity.
Resolve with ambulation or change in activity.
Relatively painless
When do real contractions happen?
When your body releases a hormone called oxytocin, which stimulates your uterus to contract.
What are contractions a sign of?
Your body being in labour
What is ‘true labour’?
When the contractions are evenly spaced (e.g. 5 mins apart), and the time between them gets shorter and shorter (3 mins apart, then 2, then 1)
As labour progresses, what happens to length of time of contraction?
Increases – 10 secs to 45 secs
Real contractions will also get more intense and painful over time
TRUE
What do contractions do?
Tighten the top part of the uterus, pushing the baby downward into the birth canal, in preparation for delivery
This also promotes thinning of the cervix
How do contractions start?
Start infrequently, and may be noticed at 10-15 minute intervals.
True labour contractions always get longer and more intense feeling. What accompany these?
Cervical changes, softening, effacement and dilatation.
What do ‘true contractions’ not resolve with?
A change of position
Are true contractions painful?
YES
Describe the uterine muscle.
Smooth muscle (myocyte) in connective tissue (collagen and elastin). Density highest at the fundus.
Describe cervical tissue.
Collagen tissue (mainly types 1, 2, 3, 4) smooth muscle, elastin, held together by connective tissue ground substance.
What leads to shortening of the muscle fibres?
Contraction and retraction
What do uterine contractions do?
Propel the baby down the birth canal, exerting pressure on the cervix.
Where is the pacemaker for uterine contractions in the region of? What does this facilitate?
The tubal ostia – facilitates a wave which spreads in a downward direction.
Describe the polarity of uterine contractions.
Upper segment contracts and retracts, while the lower segment and cervix stretch, dilate and relax.
What is intensity of contractions determined by?
Degree of uterine systole
When is the intensity of contraction maximum?
2nd stage of labour
Power of contractions can be graded as . . .
Mild, moderate of strong
What is the normal frequency of contractions?
Up to 3-4 in 10 minutes.
- allows time for resting tone.
What is the duration of contractions initially?
10-15 seconds.
What is the max duration of contractions?
45 seconds (slowly builds up).
What becomes
PROGRESSIVLEY MORE INTENSE, FREQUENT AND LONGER LASTING ?
Contractions
5/5
Head is mobile above the symphysis pubis
How can the cervix be characterized?
By evaluating 5 parameters (Bishop’s score):
- Effacement.
- Dilatation.
- Firmness.
- Position.
- Level of the presenting part or station.
We need to assess all of these factors during a vaginal examination in labour.
Anterior fontanelle shape?
Diamond
Posterior fontanelle shape?
Triangle
What are used as references for the descend of the head?
Abdominal fifths
In normal labour, how often should vaginal examinations be carried out?
4 hourly
What is the most suitable pelvic shape?
Gynaecoid pelvis.
Describe the anthropoid pelvis.
There is an oval shaped inlet with large anterio-posterior diameter and comparatively smaller transverse diameter.
Describe the android pelvis.
Triangular or heart-shaped inlet and is narrower from the front. African-Caribbean women are more at risk of having an android shaped pelvis.
What does liquor do?
Nurtures and protects the fetus, and facilitates movement.
Outline the different timings of rupture of the membranes.
- Pre-Term.
- Pre-Labour.
- First Stage.
- Second Stage.
- Born in a caul.
Outline the key stages of labour, in terms of foetal movement.
Engagement Descent Flexion Internal Rotation Crowning and extension Restitution and external rotation (head adopts optimal position for shoulder) Expulsion, anterior shoulder first
What is crowning?
The appearance of a large segment of the fetal head at the introitus.
What is stretched to full capacity during crowning?
The labia
What is the largest diameter of the fetal head encircled by during crowning?
The vulval ring
What does the mother experience during crowning?
Burning and stinging.
What may be required to prevent trauma to anal sphincters?
Episiotomy
3 classic signs indicate separation. What are these?
- Uterus contracts, hardens and rises.
- Umbilical cord lengthens permanently.
- Gush of blood variable in amount.
When, after delivery, does expulsion of the placenta usually occur? What is considered normal?
5-10 minutes.
Considered normal up to 30 minutes.
What is the plane of separation?
The spongy layer of decidua basalis.
What type of mechanical force does separation involve?
Shearing force.
Inelastic placenta reduces surface area on the placental bed due to the sustained contraction of the uterus.
TRUE
What is the method of separation?
Matthew Duncan method – marginal most common type of separation
What type of separation occurs from the central aspect?
Schultz.
What are the analgesic options during labour?
Paracetamol/ Co-codamol TENS Entonox Diamorphine Epidural Remifentanyl Combined spinal/epidural
What is entonox?
‘Gas and air’ - a mix of nitric oxide and oxygen
What volume of blood loss is normal?
<500 ml
What amount of blood loss is abnormal?
> 500 ml
What amount of blood loss is significantly abnormal?
> 1000 ml
How is haemostasis achieved naturally?
Tonic contraction: Lattice pattern of uterine muscle strangulates the blood vessels
Thrombosis of the torn vessel ends: pregnancy is a hyper-coaguable state
Myo-tamponade-opposition of the anterior/posterior walls.
What is puerperium?
A period of repair and recovery.
Puerperium - The return of tissues to a non-pregnant state in __ weeks.
6 weeks
What is lochia?
Vaginal discharge containing blood, mucous and endometrial castings.
Vaginal discharge in weeks following birth
Rubra
fresh red
Serosa
Brownish -red and watery
Alba
Yellow
How long following birth does bloodstained discharge last?
For around 10-14 days
Outline the uterine weight change which occurs.
1000g reduces to 50-100g.
What change occurs in relation to fundal height during uterine involution?
Umbilicus to within pelvis in 2 weeks.
When does the endometrium regenerate by?
The end of 1 week – except the placental site.
What commences 2-3 days postnatally?
Physiological diuresis.
What is lactation initiated by?
Placental expulsion.
What is lactation initiated by?
Placental expulsion
+
* DECREASE in oestrogen and progesterone.
* PROLACTIN is maintained
What is colostrum rich in? What is the main advantage of this?
Immunoglobulin – has a long-term protective effective.
Why can breastfeeding be problematic at the beginning?
Due to physical debility, especially after surgical intervention and psychological effects following the trauma of delivery.
