Flashcards in Normal Labour and Puperium Deck (60):
What is labour?
A physiological process during which the fetus, membranes, umbilical cord and placenta are expelled from the uterus
What is labour associated with?
Regular, painful uterine contractions with increasing frequency, intensity and duration
Biochemical changes in cervical tissue allowing cervical effacement and cervical dilatation resulting in delivery of the fetus and expulsion of the placenta
What are the 3 key factors in labour?
Power: uterine contration
Passage: maternal pelvis
What is the role of progesterone in labour?
Keeps uterus settled
Prevents the formation of gap junctions
Hinders the contractibility of myocytes
What is the role of oestrogen in labour?
Makes uterus contract
Promotes prostaglandin production
What is the role of oxytocin in labour?
Initiates and sustains contractions
Acts on decidual tissue to promote prostaglandin release
Where is oxytocin synthesised?
Directly in decidual and extraembryonic fetal tissues and in the placenta
The number of oxytocin receptors increases in myometrial and decidual tissues near end of pregnancy
What occurs in the initiation of labour?
Degree of uncertainty
Change in the estrogen/progesterone ratio
Fetal adrenals and pituitary hormones may control the timing of the onset of labour
Myometrial stretch increases excitability of myometrial fibres
Mechanical stretch of cervix and stripping of fetal membranes
What are some other known causes of possible labour initiation?
Pulmonary surfactant secreted into amniotic fluid- reported to stimulate prostaglandin synthesis
Increase in production of fetal cortisol stimulates an increase in maternal estriol
Increase in myometrial oxytocin receptors and their activation results in phospholipase C activity and subsequent increase in cytosolitic calcium and uterine contractility
What occurs in the latent phase of the first stage of labour?
Mild irregular uterine contractions, cervix shortens and softens, duration variable of up to a few days. 3-4cm dilatation
What occurs in the active phase of the first stage of labour?
4cm onwards to full dilatation
Slow descent of presenting part
Contractions progressively become more rhythmic and stronger
What happens in the second stage of labour?
Complete dilatation of cervix (10cm) to delivery of baby
Nulliparous women considered prolonged if it exceeds 3 hours if regional anaesthesia, 2 hours without
Multiparous: 2 hours with ra, 1 without
In low risk care vaginal exam not always carried out
What happens in the third stage of labour?
Delivery of baby to expulsion of placenta and fetal membranes
Average duration 10 minutes, can be 3 or longer
After 1 hour prep made for removal under GA
Active management: use of oxytocic drugs and controlled cord traction is preferred for lowering risk of post partum haemorrhage
What is the active management in the third stage of labour?
Prophylactic administration of Syntometerine: 1ml ampoule containing 500mg ergometrine maleate and 5IU oxytocin OR oxytocin 10 units
Cord clamping + cutting
Controlled cord traction
What cervical softening occur in labour?
Increase in hyaluronic acid gives increase in molecules among collagen fibres
The decrease in bridging among collagen fibres gives decrease in firmness of cervix.
What cervical ripening occurs in labour?
Decrease in collagen fibre alignment
Decrease in collagen fibre strength
Decrease in tensile strength of the cervical matrix
Increase in cervical decorin (dermatan sulphate proteoglycan 2)
What are Braxton Hicks contractions?
Tightening of uterine muscle, thought to aid the body prepare for birth
Can start 6 weeks in, usually not felt until 2nd or 3rd trimester
Can thin the cervix, but won't lead to delivery
What is a true labour contraction?
Pain starts low, rises until it peaks, and finally ebbs away. Mothers abdomen will be hard during contraction
Start about 5 minutes apart
How do Braxton Hicks contractions resolve?
Ambulation or change in activity
What do contractions do to your uterus and cervix?
Tighten top part of uterus pushing baby downward into birth canal
Promotes thinning of cervix
Describe contraction timing
Start infrequently and may be noticed at 10-15 minute intervals
Get longer and more intense feeling
What accompanies contractions?
Cervical changes, softening, effacement and dilatation
Describe the uterine muscle
Smooth muscle (myocyte) in connective tissue (collagen and elastin)
Density highest at fundus
Describe cervical tissue
Collagen tissue mainly (types 1,2,3,4), smooth muscle, elastin
Held together by connective tissue ground substance
Where is the pacemaker of the uterus and cervix?
Region of tubal ostia
Wave spreads in a downward direction
Do both ostia synchronise?
Describe the polarity of contractions
Upper segment contracts and retracts, lower segment and cervix stretch, dilate and relax
Describe the intensity of contractions?
Degree of uterine systole
Max in second stage
Grades: mild, moderate, strong
What is the frequency and duration of contractions?
Normal up to 3-4 in 10 minutes
Allows time for resting tone
Initially 10-15 secs, max 45
What is an anthropoid pelvis?
There is an oval shaped inlet with large anterio-posterior diameter and comparatively smaller transverse diameter
What is an android pelvis?
Android shaped pelvis has 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 is the most suitable female pelvic shape?
What is the liquor?
Nurtures and protects fetus and facilitates movement
What is the normal position during labour?
Presenting with vertex
OA- head engages occipito-transverse
What are the stages of delivery?
Crowning and extension
Restitution and external rotation
Expulsion, anterior shoulder first
How often should vaginal examinations be carried out during labour?
Approximately every 4 hours
Should not be carried out inappropriately just for information
What is crowning?
Appearance of a large segment of fetal head at the introitus
How stretched will labia be during crowning/
To full capacity
What is the largest diameter of the fetal head encircled by during crowning?
What parameters can be used to characterise the cervix during labour?
Level of the presenting part
What are the 5 elements of the Bishop score?
Station in Pelvis
What is the Bishop score?
Best and simplest method available to determine if it is safe to induce labour
What are some analgesia options during labour?
What is a normal blood loss in pregnancy?
Volume of less than 500ml
What is an abnormal blood loss in pregnancy?
Volume greater than 500ml
More significant if greater than 1500ml
At blood loss prior to delivery apart from 'show' is abnormal, and requires consultant unit referral
What is the plane of placental separation?
Spongy layer of decidua basalis
What are the methods of placental separation?
Matthew Duncan: marginal, the most common type of separation
Schultz: separation from central aspect
What 3 signs indicate placental separation?
Uterus contracts, hardens and rises
Umbilical cord lengthens permanently
Gush of blood variable in amount
When does expulsion of the placenta normally occur?
5-10 mins after delivery
Normal is up to 30 mins
How is haemostasis achieved in placental separation?
Tonic contraction: lattice pattern of uterine muscle strangulates the blood vessels
Thrombosis of the torn vessel: pregnancy is hyper-coagulable state
What is puerperium?
Period of repair and recovery to non-pregnant stae
How long does puerperium last?
What is lochia?
Vaginal discharge containing blood, mucus and endometrial castings
Rubra (fresh red)
Serosa (brownish red, watery)
What happens to the uterine weight in uerperium?
~1000g reduces to 50-100g
What fundal height change occurs in puerperium?
Goes from umbilicus to within pelvis in 2 weeks
How long does the endometrium take to regenerate following pregnancy?
End of a week (except placental site)
What structures regress but never go back to pre-pregnancy state?
When does diuresis commence postnatally?
What is lactation initiated by?