Normal Labour and Puerperium Flashcards
What is labour?
Physiological process during which foetal membranes, placenta and umbilical cord are expelled from uterus
What are the three options available for where to deliver?
Consultant-led unit, midwife-led unit or homebirth = 96% of women in UK still give birth in hospital setting
What are birth plans?
Record of what women would like to happen during her labour and after birth = depend on individual medical history and circumstances
What causes the initiation of labour?
Change in oestrogen:progesterone ratio
Myometrial stretch increases excitability of myometrial fibres
What hormones may control the timing of labour onset?
Foetal adrenal and pituitary hormones
What is the Feguson reflex in labour?
Pressure on internal end of cervix causes oxytocin release = stimulates uterine contractions which increase cervical pressure
What are the functions of progesterone in labour?
Keeps uterus settled, prevents formation of gap junctions, hinders myocyte contractility
What are the functions of oestrogen during labour?
Makes uterus contract, promotes prostaglandin production
What are the functions of oxytocin during labour?
Initiates and sustains contractions, acts on decidual tissue to promote prostaglandin release
Where is oxytocin synthesised?
Directly in decidual tissue and extra-embryonic foetal tissues and placenta
What happens to the number of oxytocin receptors as pregnancy goes on?
Number of receptors in myometrial and decidual tissues increases near end of pregnancy
How does pulmonary surfactant influence labour onset?
Secreted into amniotic fluid which stimulates prostaglandin synthesis
What does an increase in foetal cortisol during labour stimulate in th mother?
Stimulates increase in maternal oestriol
What does the increase in myometrial oxytocin receptors and their activation during labour result in?
Causes phospholipase C activity and subsequent increase in cytosolitic calcium and uterine contractility
What is the purpose of liquor during pregnancy?
Nurtures and protects foetus and facilitates movement
What are the different timings for membrane rupture?
Preterm, prelabour, first stage, second stage, born in caul
What does cervical tissue compose of?
Collagen tissue mainly (types 1-4), smooth muscle and elastin = held together by connective tissue ground substance
What cervical changes occur during labour?
Cervical softening and ripening
What causes cervical softening during labour?
Increase in hydraluronic acid gives increase in molecules among collagen fibres = decrease in bridging among fibres decreases cervical firmness
What happens in cervical ripening during labour?
Decrease in collagen fibre strength and alignment
Decrease in tensile strength of cervical matrix
Increase in cervical decorin
What are the advantages of the Bishops score?
Simple, easy to reproduce, good at predicting successful inductions
What is the Bishops score?
Assesses whether it’s safe to induce labour
Five elements = position, consistency, effacement, dilation, station in pelvis
What are the two components of the first stage of labour?
Latent and active phases
What occurs in the latent phase of the first stage of labour?
Up to 3-4cm dilation, mild irregular uterine contractions, cervix shortens and softens, duration variable (may be days)
What occurs in the active phase of the first stage of labour?
4cm to full dilation (10cm), slow descent of presenting part, contractions progressively become stronger and more rhythmic, normal progress is 1-2cm per hour
What contribute to the variability in the active phase of the first stage of labour?
Analgesia, mobility and parity
When is the second stage of labour?
From complete dilation of cervix to the delivery of the baby
When would the second stage of labour be considered prolonged in nulliparous women?
If it exceeds 3 hours with regional analgesia or 2 hours without
When would the second stage of labour be considered prolonged in multiparous women?
If it exceeds 2 hours with regional analgesia or 1 hour without
When is the third stage of labour?
From delivery of baby to expulsion of placenta and foetal membranes
What is the average duration of the third stage of labour?
10 minutes = can be as little as 3 minutes or much longer
When would you prepare for removal in the third stage of labour?
After 1 hour duration = give general anaesthetic
What is the management of the third stage of labour?
Expectant = spontaneous delivery of placenta Active = use of oxytocic drugs and controlled cord traction
What are Braxton-Hicks contractions?
Tightening of uterine muscles to aid body’s preparation for birth = sometimes called false labour
When do Braxton-Hicks contractions occur?
Can start from as early as 6 weeks gestation but more usually felt in third trimester
What are the features of Braxton-Hicks contractions?
Irregular, don’t increase in frequency or intensity, relatively painless, resolve with ambulation or change in activity
What are the features of true labour contractions?
Timing of contractions become evenly spaced and time between them gets progressively shorter
Duration of contraction increases and they become more intense and painful over time
What effect do contractions have?
Tighten the top part of the uterus = promotes cervical thinning, pushes baby downward into birth canal in preparation for delivery
Where is the smooth muscle density of uterine muscle highest?
At the fundus
What is the pacemaker for uterine contractions?
Region of tubal ostia = wave spreads downwards, waves from both ostia are synchronised
How does the uterus display polarity during contractions?
Upper segment contracts and retracts
Lower segment and cervix stretch, relax and dilate
What is the normal power of true labour contractions?
They have fundal dominance with regular pattern and adequate resting tone
What is the normal frequency and duration of labour cotractions?
Frequency = 3-4 in 10 minutes (allows time for resting tone) Duration = initially 10-15s, slowly builds to max of 15s
What determines the intensity of labour contractions?
Degree of uterine systole = greatest in second stage
What are the grades of labour contraction?
Mild, moderate, strong
What are the different types of pelvis?
Anthropoid, gynaecoid, android
What are the features of an anthropoid pelvis?
Oval shaped inlet with large antero-posterior diameter and relatively smaller transverse diameter
What is the most suitable pelvic shape for labour?
Gynaecoid
What are the features of an android pelvis?
Triangular or heart shaped inlet and narrower front
More common in Afro-Caribbean women
What are the five parameters used to assess the cervix?
Effacement, dilatation, firmness, position, level of presenting part
What are the normal positions for the foetus during labour?
Longitudinal lie with cephalic presentation = flexed head, presenting part is vertex
Position is occipito-anterior, head engages occipito-transverse
What are the abnormal foetal positions during labour?
Breech, oblique or transverse lie
Position is occipito-posterior
How can you determine foetal position?
Fontanelles can be felt on vaginal examination
What are the analgesia options during labour?
Paracetamol, co-codamol, TENS, entonox, remifentanyl, diamorphine, epidural or combined spinal/epidural
What is a partogram?
Graphic record of key maternal and foetal data contained in one sheet = used to assess progress of labour
What do the 7 cardinal movements refer to?
Changes in position of baby’s head in the pelvis = described in relation to vertex position
Do the cardinal movements occur in sequence?
Yes = continuous process with movements occurring one after the other
What are the seven cardinal movements?
Engagement, descent, flexion, internal rotation, crowning and extension, restitution and external rotation, expulsion
What occurs in restitution and external rotation?
Head adopts optimal position for shoulder = foetal head returns to correct anatomical position for torso
What foetal body part comes first in expulsion?
Anterior shoulder
What occurs in engagement?
Passage of widest diameter of presenting part to the level below the plane of the pelvic inlet
What occurs in descent?
Downward passage of presenting part through pelvis
When is the foetal head said to be engaged?
When widest diameter of head has entered brim of pelvis = also described as 3/5 of head entered pelvis and 2/5 still felt abdominally
What are used as reference points during descent?
Abdominal fifths
What should you observe during descent?
Maternal discomfort, feeling of pressure, frontal synciput and occipital eminences
How often are vaginal examinations carried out during descent in a normal labour?
Carried out 4 hourly for cervical assessment
What position does the foetal head assume during descent?
Occiput transverse position = widest pelvic diameter for widest part of head
When does extension occur?
Once foetus has reached level of interoitus = brings base of occiput in contact with inferior margin at symphysis pubis
What occurs during expulsion?
Delivery of rest of foetal body
What does crowning describe?
Appearance of large segment of foetal head at interoitus = labia stretched to full capacity, largest diameter of foetal head encircled by vulval ring
What may the mother feel during crowning?
Burning and stinging
How should the head be delivered during crowning?
Carefully and slowly with hands guiding exit to prevent rapid extension of tissues and perineal tearing = care of perineum vital to reduce trauma
Why may an episiotomy be required after crowning?
To prevent anal sphincter trauma
Why can immediate cord clamping cause neonatal problems?
Can reduce red blood cells received by the infant at birth by >50%
When should you delay clamping until?
Cessation of pulsations or up to three minutes post-expulsion
How long should babies have skin to skin contact with mother after birth?
Uninterrupted contact for 1 hour immediately after birth = keeps baby warm and calm, improves other aspects of transition to life outside womb
How long does it take for the placenta to be expelled after birth?
Usually occurs 5-10 minutes after delivery = considered normal up to 30 minutes
What are the signs of the third stage of labour?
Uterus contracts, hardens and rises
Permanent lengthening of umbilical cord
Gush of blood (variable in amount)
Placenta and membranes appear at introitus
What is the active management of the third stage of labour?
Prophylactic syntometrine OR oxytocin 10 units
Cord clamping and cutting, controlled cord traction and bladder emptying
How is syntometrine given in the third stage of labour?
1ml ampoule = 500mg ergometrine inaleate and 5IU oxytocin
What causes placental separation?
Shearing force = separates spongy layer of decidua basalis
What is the underlying pathophysiology of placental separation?
Inelastic placenta reduces surface area on placental bed due to sustained contraction of uterus
What are some categories of placental separation?
Matthew Duncan = most common
Schultz = separation from central aspect
How much blood can be lost in the third stage?
Normal <500ml
Abnormal >500ml
Significant if >1000ml
Is blood loss during labour considered normal?
No = any blood loss during labour prior to delivery apart from “show” is abnormal and requires referral to consultant unit
How is haemostasis achieved during pregnancy?
Tonic contraction = lattice pattern of uterine muscle strangulates vessels
Thrombosis of torn vessel ends
Myotamponade-opposition to anterior/posterior walls
What is puerperium?
Period of repair and recovery = return of tissue to non-pregnant state, takes 6 weeks
What are the discharges that can occur in puerperium?
Lochia = contains blood, mucus and endometrial castings Rubra = fresh red, 3-4 days Serosa = brownish red and watery, 4-14 days Alb = yellow, 10-20 days
How long would you expect blood stained discharge after birth?
10-14 days
What uterine changes occur during puerperium?
Uterine involution = reduction in weight from 1kg to 50-100g
How long does it take the fundal height to move from the umbilicus after delivery?
Moves from umbilicus to within pelvis within 2 weeks
How long does it take the endometrium to regenerate after birth?
Occurs by 7 days (except placental site)
What happens to the cervix, vagina and perineum after birth?
They regress, but never back to pre-pregnancy state
When does physiological diuresis commence after delivery?
Commences 2-3 days postnatally
What initiates lactation?
Placental expulsion and decrease in oestrogen and progesterone
What effect to oestrogen and progesterone have during pregnancy to prevent lactation?
Block prolactin release during pregnancy and make mammary gland cells unresponsive to prolactin
What happens to prolactin during puerperium?
Prolactin is maintained
What are the benefits of colostrum?
Rich in immunoglobulin = long term protective effect for foetus
