Second Stage Of Labour

Question 1

What does attitude mean?

Answer 1

Relationship between the fetal head and the limbs and trunk

Question 2

What is meant by the lie?

Answer 2

Relationship of fetus to long axis of the uterus

Question 3

What is meant by presentation?

Answer 3

Part of the fetus presenting in the lower aspect of the uterus

Question 4

What is meant by position?

Answer 4

Relationship of presenting part to the maternal pelvis

Question 5

What is the denominator?

Answer 5

Part of presenting part marking position (eg occiput)

Question 6

What is the second stage of labour?

Answer 6

From full dilatation of the cervix to the birth of the baby.

Question 7

Outline the characteristics of the transitional phase

Answer 7

Restlessness
Desire for pain relief
Stronger contractions but less frequent
Rupture of membranes
Expulsive contractions start

Question 8

Outline characteristics in the woman in the second stage of labour

Answer 8

Vocal changes
Eyes closing in concentration
Breathing changes 
Increased vocalisation
Involuntary bearing down

Question 9

What are the outward signs of transition?

Answer 9

Natal line (purple line)
Rhombus of michaelis
Anal dilatation
Vulval gaping
SROM
Mucous show

Question 10

What is the rhombus of michaelis?

Answer 10

Kite shaped area of bone moves backwards during the second stage of labour as it pushes the wings of the ilea out increasing diameters in the pelvis

Question 11

What is the Ferguson reflex?

Answer 11

Contractions become expulsive
Fetus descends further into vagina
Stimulation of nerve receptors in pelvic floor (positive feedback)
Woman wants to push.. Becomes compulsive
Secondary powers of expulsion abdominal muscles and diaphragm used

Question 12

Outline the physical changes as the head descends

Answer 12

Soft tissue becomes displaced
Bladder pulled up anteriorly
Urethra becomes elongated and stretched and narrowed
Posterior lay rectum becomes flattened into the sacral curve
Pressure of advancing presenting part expels any fecal matter
Perineal muscles (Levator ani) dilate and thin
Perineal body flattens stretched and thins
Fetal presenting part visible at vagina
Advances with each contraction
Crowns, head born, shoulders follow

Question 13

What position does the fetal head usually engage?

Answer 13

Occipito transverse as this is the widest diameter at the pelvic inlet
Descent then occurs

Question 14

Outline flexion as a mechanism of labour

Answer 14

Due to pressure from contractions along the long axis of the fetal pole flexion of the fetal head is encouraged.
This is physiologically beneficial as it encourages the smallest diameter of the fetal head to pass through the pelvis

Question 15

What is internal rotation?

Answer 15

The presenting part often the occiput hits the pelvic floor and will rotate forwards to lie underneath the symphysis pubis
It may now have adopted OA or OP position ideally OA

Question 16

Outline extension as a mechanism of labour

Answer 16

Once crowning has occurred the head can extend by pivoting around the pubic bone releasing the sinciput, face and chin.
These are born by the movement of extension

Question 17

Outline restitution as a mechanism of labour

Answer 17

The twist on the necks from the internal rotation is now corrected.
The occiput moves 1/8 of a circle towards the side at which it started

Question 18

Outline external rotation as a mechanism of labour

Answer 18

The shoulders rotate into the AP diameter which is the weirdest pelvic output

Question 19

Outline lateral flexion as a mechanism of labour

Answer 19

When mother is sitting the anterior shoulder is usually born first.
The anterior shoulder slips beneath the sub public arch and the posterior shoulder passes over the perineum
The remainder of the body is born by lateral flexion as the spine bends sideways through the curved birth canal

Question 20

What physiological changes occur in the second stage?

Answer 20

Increased heat generated by muscle activity
Rise in maternal pulse
Pressure on sacral plexus and obturator nerve

Question 21

How long does the seconds stage last?

Answer 21

NICE- birth would be expected to take place within 3 hours of the start of the active second stage in most nulliparous women and 2 hours in multiparous women
Time limits become prescriptive
There are no grounds for intervention if maternal and fetal condition is satisfactory
Steady progress is occurring evidenced by descent of presenting part

Question 22

Outline the physiology of the second stage

Answer 22

Cervix becomes fully dilated and has incorporated into the lower segment of the uterus
Size of uterine cavity and therefore placental site is reduced
Shortened upper segment acts as a piston with each uterine contraction that pushes the fetus lower into the pelvic cavity
Pattern of strong repeated regular contractions
Mother compelled to bear down and push
Mother inspires before pushing
Diaphragm lowered
Abdominal muscles contract
Bearing down helps overcome resistance of the soft tissues of the vagina and pelvic floor
Fetal attitude extends and is directed through the birth canal

Question 23

Outline the latent phases of the second stage

Answer 23

Full dilatation of cervix but presenting part not in pelvic outlet
No urge to bear down
Contractions may subside 10-12 mins
“Rest and be thankful”
Muscle fibres of uterine wall need to shorten and thicken further only when slack has been taken up can progress be made to expulsive contractions and descent
Stretch receptors in vagina, recumbent and perineum communicate change in volume,tension and tone
Passive cent should be allowed until presenting part visible

Question 24

Outline the signs that birth is imminent

Answer 24

Congestion of vulva, dilatation, gaping of anus
Pass of faeces
Involuntary suing
Forewaters rupture
Maternal behaviour - vomiting, panic, anxiety, overwhelmed
Bright red vaginal loss
Woman more vocal, low grunting noises
Restless, strong desire to change position
Need to grasp

Question 25

Outline the active phase of the second stage

Answer 25

Urge to push allows the presenting part to descend to compress the tissues of the pelvic floor
1cm above ischial spines nerve receptors are stimulated in pelvic floor (ferguson reflex) uncontrollable urge to push
Expulsive contractions

Question 26

What is the fetal ejection reflex?

Answer 26

Steep rise in catecholamines during last minutes before birth leads to woman being very alert
Fetus releases them too wide eyed at mother

Question 27

How is the fetal ejection reflex shown?

Answer 27

Sudden fear expressed in irrational way due to surge in hormones such as adrenaline
Immediately followed by irresistible contractions

Question 28

What is the valsalva manoeuvre?

Answer 28

Forceful attempted exhalation against closed airways, closed glottis

Question 29

What happens to the body in the valsalva manoeuvre?

Answer 29

Closed pressure system in the chest
Reduction in venous return
Reduction in cardiac output
Reduced BP
Reduced blood flow to placenta
Peripheral stasis in head and face (redness)
Maternal O2 levels reduced CO2 levels increased
Gasping for air causes sudden increase in BP, potential rupture of capillaries in face and neck
O2 to fetus reduced

Question 30

What hormonal influences occur in labour?

Answer 30

Oxytocin
Accumulation in pregnancy causes memory loss, nesting behaviour, relaxed
Highly sensitive to stress and anxiety

Placental growth hormone levels decline in early labour

Sharp fall in prolactin levels 2 hours before birth

High circulating levels of oestrogen, progesterone and cortisol inhibit insulin secretion

Changes reduce maternal appetite, enhance maternal glucose tolerance and reduce insulin secretion