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ESA 4 - Reproductive System > Partuition > Flashcards

Flashcards in Partuition Deck (137)
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1
Q

What is parturition?

A

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

2
Q

How can parturition occur?

A

Labour or c-section

3
Q

What is considered to be parturition?

A

Expulsion of the products of conceptus after 24 weeks

4
Q

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

A

Because 24 weeks is the legal limit of viability

5
Q

Why is 24 weeks considered the legal limit of viability?

A

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

6
Q

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

A

Spontaneous abortion

7
Q

What is it called when parturition occurs before 36 weeks?

A

Pre-term delivery

8
Q

What is pre-term delivery associated with?

A

Small baby
Neurogenic defects
Lung problems
Problems with gut and liver

9
Q

What neurogenic defects can occur with pre-term delivery?

A

Deaf
Blind
Cerebral palsy

10
Q

What is considered to be a term delivery?

A

37-42 weeks

11
Q

What is it called when parturition occurs after 42 weeks?

A

Post-term

12
Q

When does death of the fetus occur post-term?

A

42 weeks

13
Q

When does death of the mother occur post-term?

A

42 weeks and 6 days

14
Q

When are women inducted in the UK?

A

41 weeks and 3 days

15
Q

How is labour induction done?

A

Membrane rupture

Drugs

16
Q

What is labour?

A

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

17
Q

Why is the term labour often used instead of parturition?

A

Because lay people use it

18
Q

What is actually the case regarding labour and parturition?

A

It is just one part

19
Q

What are the stages of labour?

A

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

20
Q

What is the birth canal made up of?

A

Pelvis and pelvic organs

21
Q

What happens to the baby and placenta after birth?

A

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

22
Q

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

A

If placenta too large, small, or calcified

23
Q

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

A

Increases dramatically (obviously)

24
Q

When is the uterus palpable in pregnancy?

A

By about 12 weeks

25
Q

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

A

Small bump just above pubic symphysis

26
Q

When does the fetus and uterus reach the umbilicus?

A

By about 20 weeks

27
Q

When does the fetus and uterus reach the xiphisternum?

A

About 36 weeks

28
Q

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

A

It is starting to turn head downwards

29
Q

What is fundal height measured as?

A

Cm from pubic symphysis to uppermost portion of uterus

30
Q

What is the measurement of fundal height useful for?

A

To monitor progression of pregnancy

31
Q

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

A

Fetal position

32
Q

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

A

Lie
Presentation
Vertex

33
Q

What is meant by fetal lie?

A

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

34
Q

What should the fetal lie be?

A

Parallel, with the fetus flexed

35
Q

What is meant by fetal presentation?

A

The part that is adjacent to the pelvic inlet

36
Q

What is the normal fetal presentation?

A

Crown of the head - termed cephalic

37
Q

What are the abnormal fetal presentations?

A

Buttocks - termed podalic, or breech
Face
Brow
Shoulder

38
Q

What is the problem with shoulder presentation?

A

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

39
Q

What is meant by fetal vertex?

A

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

40
Q

What is the normal fetal vertex?

A

About 45 degrees

41
Q

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

A

At minimum diameter

42
Q

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

A

The pelvis

43
Q

What is the average size of the pelvic inlet?

A

11cm

44
Q

What is the biggest part in a normal presentation?

A

The head

45
Q

What is the diameter of the presentation of the head?

A

9.5cm

46
Q

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

A

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

47
Q

What may increase the size of the pelvic inlet?

A

Softening of the ligaments by collagenases

48
Q

How is the birth canal created?

A

By expansion of soft tissues

49
Q

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

A

Not much

50
Q

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

A

MMP enzymes

51
Q

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

A

Effacement

A lot of force

52
Q

What is effacement?

A

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

53
Q

What is considered early effacement?

A

30% of the way to fully effaced

54
Q

What is early effacement caused by?

A

Little contractions in the ithsmus of the uterus

55
Q

What is considered to be complete effacement?

A

When the internal and external os touch

56
Q

Why does the cervix have to remain closed during pregnancy?

A

So the products of conception don’t fall out

57
Q

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

A

Previous cervical surgery or cancer

58
Q

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

A

Put a stitch in

59
Q

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

A

Needs to be tough and thick, with lots of collagen

60
Q

What needs to happen to the cervix in labour?

A

Needs to undergo softening

61
Q

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

A

Cervical ripening

62
Q

What happens in cervical ripening?

A

Changes in the cervix collagen in proteoglycan matrix

63
Q

How is the cervix collagen changed in cervical ripening?

A

Reduction in collagen
Increase in glycosaminoglycans
Increase in hyaluronic acid

64
Q

What produces a reduction in collagen in cervical ripening?

A

MMP2 and MMP9 enter the cervix and perform enzymatic degradation

65
Q

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

A

Oestrogen

66
Q

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

A

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

67
Q

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

A

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

68
Q

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

A

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

69
Q

What is cervical ripening triggered by?

A

Prostaglandins

70
Q

What prostaglandins trigger cervical ripening?

A

PGE2 and PGF2-alpha

71
Q

What generates the force in labour?

A

Myometrium

72
Q

What happens to the myometrium in pregnancy?

A

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

73
Q

When are action potentials generated in the myometrium?

A

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

74
Q

When do uterine contractions occur in pregnancy?

A

Throughout pregnancy

75
Q

Describe the uterine contractions in early pregnancy

A

Low amplitude - some reach threshold and cause a twinge

Every 30 minutes

76
Q

Describe the uterine contractions in middle pregnancy

A

Less frequent, higher amplitude, known as ‘Braxton-Hicks’ contractions

77
Q

What is happening with Braxton-Hicks contractions?

A

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

78
Q

What is the importance of Braxton-Hicks contractions?

A

In first pregnancy, might think they are going into labour

79
Q

Describe the contractions in early labour?

A

Variable, but high amplitude

80
Q

What do the contractions in early labour cause?

A

Increasing pain and backache

81
Q

Describe the contractions in late labour?

A

More frequent and higher amplitude

82
Q

What is clinical labour considered to be?

A

59 second or more contractions, 3x in 10 minutes

83
Q

What makes uterine contractions more forceful and frequent?

A

Prostaglandins

Oxytocin

84
Q

What effect to prostaglandins have on uterine contractions?

A

More Ca per action potential

85
Q

What effect to oxytocin have on uterine contraction?

A

More action potentials because lower threshold

86
Q

What are prostaglandins?

A

Biologically active lipids that act as local hormones

87
Q

Where are prostaglandins produced?

A

Mainly in myometrium and decidua

88
Q

What controls the production of prostaglandins?

A

Oestrogen:progesterone ratio

89
Q

What does a low oestrogen:progesterone ratio cause?

A

Low prostaglandins

90
Q

What does a high oestrogen:progsterone ratio cause?

A

Increased prostaglandins

91
Q

When does oestrogen begin to predominate in pregnancy?

A

When human chorionic gonadotrophin production reduces

92
Q

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

A

It increases prostaglandins, which;

  • Ripens cervix
  • Promotes uterine contractions
93
Q

What is oxytocin secreted by?

A

Posterior pituitary

94
Q

What is secretion of oxytocin controlled by?

A

Hypothalamus

95
Q

What increases the secretion of oxytocin?

A

Afferent impulses from the cervix and vagina - the Ferguson reflex

96
Q

Show the Ferguson reflex

A

Picture

97
Q

What does oxytocin act on?

A

Smooth muscle receptors

98
Q

When are there more oxytocin receptors?

A

If oestrogen:progesterone ratio is high

99
Q

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

A

Increases

100
Q

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

A

Cervix ripens
Uterine contractions more forceful
Brachystasis

101
Q

What happens in cervical ripening at the onset of labour?

A

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

102
Q

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

A

10cm

103
Q

How is cervix dilation measured with fingers?

A

1 finger = 2.5cm

4 fingers = 10cm

104
Q

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

A

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

105
Q

What happens in brachystasis?

A

The uterus relaxes less than it contracts

106
Q

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

A

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

107
Q

What is created by brachystasis?

A

A ratcheting system

108
Q

How is labour initiated in animals?

A

Rise in oestrogen:progesterone ratio

109
Q

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

A

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

110
Q

How is labour initiated in sheep?

A

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

111
Q

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

A

Because sheep have 1, 2, or 3 lambs

112
Q

What promotes labour in humans?

A

Prostaglandins

113
Q

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

A

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
Q

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

A

Some women have increased progesterone towards the end of pregnancy

115
Q

How does surfactant protein A stimulate the production of prostaglandins?

A

It crosses the fetal membranes and stimulates macrophages to produce prostaglandins

116
Q

How long is the second stage of labour?

A

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

117
Q

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

A

Parity

118
Q

What is initiated in the second stage of labour?

A

The urge to ‘bear down’ and ‘push’

119
Q

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

A

Need abdominal muscles to help push out

120
Q

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

A

The presenting part

121
Q

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

A

Crowning

122
Q

What is done once a baby is crowning?

A

Mother told to push

123
Q

What is meant by ‘breech’?

A

When the presenting part is buttocks, shoulder, or knee

124
Q

What must happen if the fetus is breech?

A

Fetus has to be turned - converted

125
Q

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

A

Footling breech

126
Q

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

A

It flexes and rotates internally

127
Q

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

A

Stretch it, with a risk of tearing

128
Q

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

A

Epistiotomy

129
Q

What complications can arise from epistiotomies?

A

Fistulae along gut and vagina

130
Q

What happens once the head has been delivered?

A

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

131
Q

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

A

It is dramatically increased by expulsion of fetus

132
Q

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

A

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

133
Q

How long does the third stage of labour normally take?

A

10 minutes

134
Q

What is done once the placenta has been expelled?

A

Wait 3 minutes before clamping it

135
Q

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

A

Allows blood to pump to the baby, preventing neonatal jaundice

136
Q

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

A

Compresses spiral arteries, reducing post-partum haemorrhage

137
Q

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

A

Oxytocic drug

Manual fundal massage