Partuition Flashcards Preview

ESA 4 - Reproductive System > Partuition > Flashcards

Flashcards in Partuition Deck (137):
1

What is parturition?

The scientific term used to describe the transition from the pregnant state to the non-pregnant state at the end of gestation

2

How can parturition occur?

Labour or c-section

3

What is considered to be parturition?

Expulsion of the products of conceptus after 24 weeks

4

Why must it be after 24 weeks to be considered parturition?

Because 24 weeks is the legal limit of viability

5

Why is 24 weeks considered the legal limit of viability?

Because after this, the baby can survive outside of the uterus and has legal rights

6

What is it called when the expulsion of the products of conceptus occurs before 24 weeks?

Spontaneous abortion

7

What is it called when parturition occurs before 36 weeks?

Pre-term delivery

8

What is pre-term delivery associated with?

Small baby
Neurogenic defects
Lung problems
Problems with gut and liver

9

What neurogenic defects can occur with pre-term delivery?

Deaf
Blind
Cerebral palsy

10

What is considered to be a term delivery?

37-42 weeks

11

What is it called when parturition occurs after 42 weeks?

Post-term

12

When does death of the fetus occur post-term?

42 weeks

13

When does death of the mother occur post-term?

42 weeks and 6 days

14

When are women inducted in the UK?

41 weeks and 3 days

15

How is labour induction done?

Membrane rupture
Drugs

16

What is labour?

The non-scientific term used to describe parturition when both the cervix and the uterus have been remodelled

17

Why is the term labour often used instead of parturition?

Because lay people use it

18

What is actually the case regarding labour and parturition?

It is just one part

19

What are the stages of labour?

First stage- creation of birth canal
Second stage- expulsion of fetus
Third stage- expulsion of placenta and contraction of uterus

20

What is the birth canal made up of?

Pelvis and pelvic organs

21

What happens to the baby and placenta after birth?

They are both weighed to ensure they are roughly the same size

22

When will paediatrician attention be required following weighing of baby and placenta?

If placenta too large, small, or calcified

23

What happens to the size of the fetus and uterus during pregnancy?

Increases dramatically (obviously)

24

When is the uterus palpable in pregnancy?

By about 12 weeks

25

What is the uterus palpable as at 12 weeks of pregnancy?

Small bump just above pubic symphysis

26

When does the fetus and uterus reach the umbilicus?

By about 20 weeks

27

When does the fetus and uterus reach the xiphisternum?

About 36 weeks

28

What is happening to the position of the fetus at about 36 weeks?

It is starting to turn head downwards

29

What is fundal height measured as?

Cm from pubic symphysis to uppermost portion of uterus

30

What is the measurement of fundal height useful for?

To monitor progression of pregnancy

31

What needs to be assessed towards the end of the pregnancy?

Fetal position

32

What aspects of fetal position need to be assessed towards the end of pregnancy?

Lie
Presentation
Vertex

33

What is meant by fetal lie?

The relationship of the vertebral column to the long axis of the uterus

34

What should the fetal lie be?

Parallel, with the fetus flexed

35

What is meant by fetal presentation?

The part that is adjacent to the pelvic inlet

36

What is the normal fetal presentation?

Crown of the head - termed cephalic

37

What are the abnormal fetal presentations?

Buttocks - termed podalic, or breech
Face
Brow
Shoulder

38

What is the problem with shoulder presentation?

Dangerous because can cause shoulder dystocia, and can loose baby easily

39

What is meant by fetal vertex?

The relationship of the fetus along its axis; the orientation of the presenting part in relation to the spinal cord

40

What is the normal fetal vertex?

About 45 degrees

41

What is normally true of the vertex to the pelvic inlet?

At minimum diameter

42

What is the maximum size of the birth canal determined by?

The pelvis

43

What is the average size of the pelvic inlet?

11cm

44

What is the biggest part in a normal presentation?

The head

45

What is the diameter of the presentation of the head?

9.5cm

46

What happens if the babys head is bigger than the canal?

It won't come out, and requires a C-section

47

What may increase the size of the pelvic inlet?

Softening of the ligaments by collagenases

48

How is the birth canal created?

By expansion of soft tissues

49

How much does the perineum expand in the creation of the birth canal?

Not much

50

How are the cervix and vagina stretched to create the birth canal?

MMP enzymes

51

What does the creation of the birth canal by expansion of the tissue require?

Effacement
A lot of force

52

What is effacement?

The process by which the internal os and external os of the cervix are close together

53

What is considered early effacement?

30% of the way to fully effaced

54

What is early effacement caused by?

Little contractions in the ithsmus of the uterus

55

What is considered to be complete effacement?

When the internal and external os touch

56

Why does the cervix have to remain closed during pregnancy?

So the products of conception don't fall out

57

What increases the risk of the products of conception falling out from the cervix during pregnancy?

Previous cervical surgery or cancer

58

What can be done when there is an increased risk of the products of conception falling out of the cervix during pregnancy?

Put a stitch in

59

What needs to be true of the cervix to retain the fetus?

Needs to be tough and thick, with lots of collagen

60

What needs to happen to the cervix in labour?

Needs to undergo softening

61

What is the softening process of the cervix during labour termed?

Cervical ripening

62

What happens in cervical ripening?

Changes in the cervix collagen in proteoglycan matrix

63

How is the cervix collagen changed in cervical ripening?

Reduction in collagen
Increase in glycosaminoglycans
Increase in hyaluronic acid

64

What produces a reduction in collagen in cervical ripening?

MMP2 and MMP9 enter the cervix and perform enzymatic degradation

65

What is the reduction in collagen by MM2 and MMP9 in labour under the influence of?

Oestrogen

66

What is the effect of an increase in glycosaminoglycans in cervical ripening?

Seperates the strands of collagen, and so allow MMP2 and 9 to get into the collagen and break it down further

67

What is the effect of an increase in hyaluronic acid in the cervix in labour?

Very hydrophilic, so brings water into the tissue, causing it to expand and reducing the aggregation of collagen fibres

68

What causes an increase in hyaluronic acid in the cervix in labour?

Rubbing of 2 tissues - the cervix against the babies head - causing blistering

69

What is cervical ripening triggered by?

Prostaglandins

70

What prostaglandins trigger cervical ripening?

PGE2 and PGF2-alpha

71

What generates the force in labour?

Myometrium

72

What happens to the myometrium in pregnancy?

The smooth muscle becomes much thickened, from 0.5cm to 2.5cm

73

When are action potentials generated in the myometrium?

When intracellular [Ca] rises due to spontaneous triggering by pacemaker cells in fundus

74

When do uterine contractions occur in pregnancy?

Throughout pregnancy

75

Describe the uterine contractions in early pregnancy

Low amplitude - some reach threshold and cause a twinge
Every 30 minutes

76

Describe the uterine contractions in middle pregnancy

Less frequent, higher amplitude, known as 'Braxton-Hicks' contractions

77

What is happening with Braxton-Hicks contractions?

Uterus is getting ready for labour, and the fibres are coming together to eventually all act as one cell

78

What is the importance of Braxton-Hicks contractions?

In first pregnancy, might think they are going into labour

79

Describe the contractions in early labour?

Variable, but high amplitude

80

What do the contractions in early labour cause?

Increasing pain and backache

81

Describe the contractions in late labour?

More frequent and higher amplitude

82

What is clinical labour considered to be?

59 second or more contractions, 3x in 10 minutes

83

What makes uterine contractions more forceful and frequent?

Prostaglandins
Oxytocin

84

What effect to prostaglandins have on uterine contractions?

More Ca per action potential

85

What effect to oxytocin have on uterine contraction?

More action potentials because lower threshold

86

What are prostaglandins?

Biologically active lipids that act as local hormones

87

Where are prostaglandins produced?

Mainly in myometrium and decidua

88

What controls the production of prostaglandins?

Oestrogen:progesterone ratio

89

What does a low oestrogen:progesterone ratio cause?

Low prostaglandins

90

What does a high oestrogen:progsterone ratio cause?

Increased prostaglandins

91

When does oestrogen begin to predominate in pregnancy?

When human chorionic gonadotrophin production reduces

92

What is the result of the relative fall in progesterone when hCG production falls?

It increases prostaglandins, which;
- Ripens cervix
- Promotes uterine contractions

93

What is oxytocin secreted by?

Posterior pituitary

94

What is secretion of oxytocin controlled by?

Hypothalamus

95

What increases the secretion of oxytocin?

Afferent impulses from the cervix and vagina - the Ferguson reflex

96

Show the Ferguson reflex

Picture

97

What does oxytocin act on?

Smooth muscle receptors

98

When are there more oxytocin receptors?

If oestrogen:progesterone ratio is high

99

What happens to the level of prostaglandins at the onset of labour?

Increases

100

What is the result of the increased prostaglandins at the onset of labour?

Cervix ripens
Uterine contractions more forceful
Brachystasis

101

What happens in cervical ripening at the onset of labour?

Cervix thins and flattens in process called effacement
Ferguson reflex stimulates oxytocin release
Cervix begins to dilate
Rupture of amnion

102

How dilated is the cervix by the end of the first stage?

10cm

103

How is cervix dilation measured with fingers?

1 finger = 2.5cm
4 fingers = 10cm

104

How long does it take for the cervix to be fully dilated?

Can take many hours;
96 hours in first pregnancy
24 hours in previous pregnancies

105

What happens in brachystasis?

The uterus relaxes less than it contracts

106

What is the result of the uterus relaxing less than it contracts?

Pulls fibres along their longitudinal axis, driving the presenting part to the cervix

107

What is created by brachystasis?

A ratcheting system

108

How is labour initiated in animals?

Rise in oestrogen:progesterone ratio

109

How is a rise in oestrogen:progesterone ratio bought about in the initiation of labour in animals?

Placenta makes less progesterone, so increased prostaglandins and increased myometrial sensitivity to oxytocin (because more receptors)

110

How is labour initiated in sheep?

Due to rise in fetal cortisol, which goes to placenta and decreases production of progesterone

111

Why is looking at sheep labour a good model for what happens in humans?

Because sheep have 1, 2, or 3 lambs

112

What promotes labour in humans?

Prostaglandins

113

Why is the the relationship between progesterone and the initiation of labour in humans unclear?

Humans with no adrenals get born
No consistent evidence of progesterone:oestrogen changes
Evidence that surfactant protein A produced by fetal lungs causes prostaglandin production in myometrium

114

Why is there no consistent evidence that progesterone:oestrogen changes initiate labour?

Some women have increased progesterone towards the end of pregnancy

115

How does surfactant protein A stimulate the production of prostaglandins?

It crosses the fetal membranes and stimulates macrophages to produce prostaglandins

116

How long is the second stage of labour?

Relatively rapid - up to 1 hour, but can be very fast

117

What does the duration of the second stage of labour depend on?

Parity

118

What is initiated in the second stage of labour?

The urge to 'bear down' and 'push'

119

Why is the urge to push initiated in the second stage of labour?

Need abdominal muscles to help push out

120

What appears in the birth canal at the second stage of labour?

The presenting part

121

What is it called if the presenting part appearing in the birth canal is the top of the head?

Crowning

122

What is done once a baby is crowning?

Mother told to push

123

What is meant by 'breech'?

When the presenting part is buttocks, shoulder, or knee

124

What must happen if the fetus is breech?

Fetus has to be turned - converted

125

What is it called when the presenting part is the foot?

Footling breech

126

What happens to the head of the fetus during the second stage of labour?

It flexes and rotates internally

127

What does the head of the fetus do to the vagina and perineum?

Stretch it, with a risk of tearing

128

What can be done if there is a risk of tearing of the perineum?

Epistiotomy

129

What complications can arise from epistiotomies?

Fistulae along gut and vagina

130

What happens once the head has been delivered?

The head rotates and extends, shoulders rotate and deliver, followed rapidly by the rest

131

What happens to the effect of uterine contractions in the third stage of labour?

It is dramatically increased by expulsion of fetus

132

What is the result of uterine contractions in the third stage of labour?

The uterus contracts down hard and shears off the placenta to expel it

133

How long does the third stage of labour normally take?

10 minutes

134

What is done once the placenta has been expelled?

Wait 3 minutes before clamping it

135

Why should you wait 3 minutes before clamping the placenta after delivery?

Allows blood to pump to the baby, preventing neonatal jaundice

136

What is the importance of uterine contractions in the third stage of labour?

Compresses spiral arteries, reducing post-partum haemorrhage

137

How can uterine contractions be enhanced in the third stage of labour?

Oxytocic drug
Manual fundal massage