Normal Labour and Puerperium Flashcards
(55 cards)
Define labour?
Physiological process during which the foetus, membranes, umbilical cord and placenta are expelled from the uterus
Usually assoc. with regular, painful uterine contractions with increasing frequency, intensity and duration and accompanied by biochemical changes in the cervical tissue, allowing cervical effacement and cervical dilatation
This results in delivery of the foetus and expulsion of the placenta
What is puerperium?
6 weeks following labour
3 key factors allow labour?
- Power - uterine contractions
- Passage - maternal pelvis
- Passenger - foetus
Physiological factors that allow labour to occur?
Progesterone - keeps the uterus settled; it prevents the formation of gap junctions and hinders the contractability of myocytes
Oestrogen - makes the uterus contract and this promotes PG production
Oxytocin - synthesised in decidual and extra-embryonic foetal tissues and in the placenta; this initiates and sustains contractions and it also acts on decidual tissue to promote PG release
The no. of oxytocin receptors increases in myometrial and decidual tissues near the end of the pregnancy
How is labour initiated?
There is a degree of uncertainty but the following factors may be inv:
• Change in the oestrogen / progesterone ratio
• Foetal adrenals and pituitary hormones may control the timing of the onset of labour
• Myometrial stretch increases excitability of myometrial fibres
• Mechanical stretch of the cervix and stripping of foetal membranes
• Ferguson’s reflex
• Pulmonary surfactant secreted into amniotic fluid has been reported to stimulate PG synthesis
• Increased in production of foetal cortisol stimulates an increase in maternal oestriol
• Increase in myometrial oxytocin receptors and their activation results in phospholipase C activity and subsequent increase in cytosolitic Ca and uterine contractility
What is Ferguson’s reflex?
Neuroendodrine reflex comprising the self-sustaining cycle of uterine contractions, initiated by P at the cervix or vaginal walls
What is Bishop’s score?
Used to determine whether IOL is required and whether it is safe to do so; equal weight is given to each of the 5 elements: • Position • Consistency • Effacement • Dilatation • Station in the pelvis
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Stages of labour?
- 1st stage - consists of 2 phases:
• Latent phase - there is up to 3-4 cm dilatation
• Active phase - dilatation progresses from 4 to 10 cm, i.e: full dilatation - 2nd stage - with full dilatation, the baby is delivered
- 3rd stage - there is expulsion of the placenta and membranes
Features of the latent phase of labour (in the 1st stage)?
Mild, irregular uterine contraction, with variable duration
Cervix shortens and softens
This stage is very unpredictable and can vary from being only a few hours to a few days; essentially, the latent phase prepares for labour
Features of the active phase of labour (in the 1st stage)?
Cervical dilatation of 4 cm onwards; normal progress is assessed at 1-2 cm per hour
There is slow descent of the presenting part
Contractions progressively become stronger and more rhythmic
NOTE - analgesia, mobility and parity all increase variability
Features of the 2nd stage of labour?
Begins with complete dilatation of the cervix, i.e: 10cm, to delivery of the baby
How does the timing of the 2nd stage of labour vary between different women?
In nulliparous women, this stage is considered prolonged if it:
• Exceeds 3 hours, with regional analgesia
• Exceeds 2 hours, without analgesia
In multiparous women, this stage is considered prolonged if it:
• Exceeds 2 hours with regional analgesia
• Exceeds 1 hours without analgesia
How often are vaginal examinations done during labour?
In low risk care, vaginal examinations are not always carried out to assess time of full dilatation (in normal labour, examine 4 hourly)
Should not be done inappropriately just for info
Features of the 3rd stage of labour?
Average duration of 10 minutes, but can be 3 minutes or longer
After 1 hour, preparation is made for removal under general anaesthetic
Mx of the 3rd stage of labour?
Expectant Mx - spontaneous delivery of the placenta
Active Mx: • Oxytocic drugs • Cord clamping and cutting • Controlled cord traction (preferred due to the lower risk of PPH) • Bladder emptying
What are the oxytocic drugs used for active Mx of the 3rd stage of labour?
Prophylactic administration of:
• Syntometerine (1ml ampoule containing 500 micrograms ergometrine maleate and 5iu oxytocin)
• Oxytocin 10 units
How do the cervical changes occur in labour?
Complex biochemical process causes cervical softening and ripening
Cervical softening due to:
• Increase in hyaluronic acid increases the molecules among the collagen fibres
• Decrease in bridging among collagen fibres gives decrease in firmness of cervix
Cervical ripening due to: • Decrease in collagen fibre alignment • Decrease in collage fibre strength • Decrease in tensile strength of the cervical matrix • Increase in cervical decorin
What are Braxton Hicks contractions?
AKA false labour, practice contractions, etc
Tightening of the uterine muscles, which aid the body to prepare for birth; the woman has a false sensation of real contractions
They can thin the cervix but they will not ultimately lead to delivery
When do Braxton Hicks contractions begin?
Can start 6 weeks into pregnancy but are more usually felt in the 3rd trimester
Not usually felt until the 2ND OR 3RD TRIMESTER
Characteristics of Braxton Hicks contractions?
Irregular; they do not increase in frequency or intensity
Resolve with ambulation or a change in activity
Relatively painless
Characteristics of true labour contractions?
Contractions are evenly spaced, e.g: 5 minutes apart; the time between gets SHORTER and the DURATION INCREASES (from 10 to 45 seconds)
Generally, they are painful
They also become MORE INTENSE and painful over time
Contractions do not resolve with a change in position
Accompanying cervical changes, softening, effacement and dilatation
Feeling of a true contraction is described as a WAVE, starting low and then rising until it peaks before ebbing away; if the mother’s abdomen is felt, it hardens during the contraction and this can be timed
Duration of true labour contractions?
Start about 5-10 minutes apart
Mechanics of uterine contractions?
Uterine muscle - smooth muscle in CT; the density is highest at the fundus
Cervical tissue - mainly collagen tissue, smooth muscle and elastin held together by CT ground substance
Contraction and retraction leads to shortening of the muscle fibres; this propels the baby down the birth canal and exerts P on the cervix
Power of uterine contractions?
Pacemaker is in the region of the tubal ostia and the wave spreads in the downward direction; as waves come from both ostia, the contractions are synchronised
