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ESA 4 - Reproductive System > Problems with Labour > Flashcards

Flashcards in Problems with Labour Deck (127):
1

What is labour? 

The physiological process by which a fetus is expelled from the uterus to the outside world 

2

What does the process of labour involve? 

The sequential integrated changes in uterine decidua, and myometrium 

3

What tends to precede uterine contractions in labour? 

Changes in the uterine cervix

4

How do Braxton-Hicks contractions differ from labour? 

They do not cause the cervix to dilate 

5

What are the two main goals of uterine contractions in labour? 

  • Dilate cervix
  • Push fetus through birth canal 

 

6

What are the three P's of labour problems? 

  • Powers
  • Passenger
  • Passage

 

7

What effect does the oestrogen/progesterone ratio have on the uterine musculature in labour? 

It changes to increase excitability 

8

What effect does progesterone have on the uterine musculature in labour? 

It inhibits contraction by reducing the excitability of muscles 

9

What effect does oestrogen have on the uterine musculature in labour? 

Increases gap junctional communication between smooth muscle cells, increasing contractility 

10

What effect does oxytocin have on uterine musculature during labour? 

Increases excitability 

11

Where is oxytocin secreted from? 

Maternal posteiror pituitary gland 

12

What effect does mechanically stretching uterine smooth muscle in labour have? 

Increases contractility 

13

What does cervical stretching elicit in labour?

Uterine contractions

14

How do fetal effects contribute to labour? 

  • Fetus produces hormones which increase glucocorticoids from the placenta, which inhibits progesterone.
  • Fetal oxytocin is produced 

 

15

What can be given to induce labour? 

Prostaglandins 

16

How can prostaglandins be given to induce labour? 

Oral or into vagina

17

Give an example of when labour may need to be induced 

In pre-eclampsia 

18

What are prostaglandins? 

Powerful contractors of smooth muscle 

19

What are prostaglandins involved in, regarding the cervix? 

Cervical softening 

20

What stimulates prostaglandin synthesis in labour? 

  • Increase in oestrogen:progesterone ratio
  • Mechanical damage

 

 

21

What synthesises prostaglandins in pregnancy? 

  • Placenta
  • Decidua
  • Myometrium
  • Membranes 

 

22

What happens to prostaglandin synthesis in the third trimester? 

There is increased synthesis by the amnion 

23

What happens to the levels of prostaglandins in amniotic fluid very early in labour? 

They rise 

 

24

What is cervical ripening due to? 

Oestrogen, relaxin, and prostaglandins breaking down the connective tissue 

25

What does oxytocin do in labour? 

Initiates uterine contractions 

26

What happens to the action of oxytocin during pregnancy? 

It is inhibited by progsterone, relaxin, and low number of oxytocin receptors 

27

What happens to the number of gap junctions during pregnancy? 

It increases

28

Why does the number of gap junctions increase in pregnancy? 

To aid communication between muscle cells, which coordinates uterine activity

29

What happens to the myometrium at 36 weeks of pregnancy? 

There is an increased number of oxytocin receptors in the myometrium 

30

What is the result of the increased number of oxytocin receptors in the myometrium from 36 weeks? 

Uterus can respond to pulsatile release of oxytocin from posterior pituitary gland

31

What special properties does the myometrium have? 

Does not act like smooth muscle normally does in that myometrial fibres contract, but only partially relax, and so myometrial muscle does not return to its original size, and there is pernament partial shortening of muscle fibres 

32

What is the result of the pernament partial shortening of the muscle fibres of the myometrium? 

Propels fetus furthern into pelvis

33

What are the features of the contration of the myometrium in labour? 

  • Symmetry and polarity
  • Retraction

 

34

What is meant by symmetry and polarity in myometrial contraction? 

The contrations create two poles of uterus, then go to fundus and upper part of uterus, then down to the lower segment 

35

What is the result of symmetry and polarity of myometrial contraction? 

The forces of the upper segment are more powerful than that of the lower segment of the utersu 

36

What is meant by retraction in the contraction of the myometrium? 

After each contraction, the length of the myometrium muscle of the uterus cannot return to the former length, it becomes shorter and shorter. 

37

What is the result of retraction of the myometrium? 

The uterine capacity is progressively reduced so the pressure inside the uterus becomes stronger and stronger 

38

How many contractions are required for an effective labour? 

3-4 in 10 minutes 

39

What happens to levels of relaxin during pregnancy? 

Levels increase 

40

What is the result of increasing levels of relaxin during pregnancy? 

Causes changes in the cervix 

41

What changes in the cervix are caused by increasing levels of relaxin? 

Causes enzymes to degrade collagen and so changes in collagen to ground substance ratio 

42

Over what time period to the changes in the cervix caused by relaxin occur? 

Period of weeks, evident from 36/40

43

How does a labour cervix allow for delivery? 

Offers less resistance to the presenting part 

44

What are the cervical changes during labour known as? 

Effacement and dilatation 

45

Describe the cervix in mid-pregnancy? 

Unripe - form, not much give, tubular, closed 

46

What happens to the cervix in late pregnancy? 

It softens 

47

What causes the changes in the cervix from early to late pregnancy? 

Oestrogen, prostaglandins, and relaxin increase, causing dispersion of proteoglycan complexes and an increase in collagenase 

48

Describe a term cervix

Softened and effaced 

49

What causes the changes in the cervix between late pregnancy and term? 

Uterine contractions before and during labour cause retraction of the myometrium 

50

When is a cervix considered to be fully dilated? 

When it can't be felt

51

What is the ideal pelvis for childbirth? 

Gynecoid 

52

What are the features of a gynaecoid pelvis? 

  • Wide forepelvis
  • Straight side walls
  • Wide suprapubic arch 

 

 

53

What pelvices may cause problems in delivery? 

  • Anthropoid 
  • Android
  • Platpelloid 

 

54

Describe the features of an anthropoid pelvis

  • Narrow transverse diameter
  • Wide AP diameter
  • Divergent forepelvis
  • Narrow side walls
  • Wide inclination of the sacrum 

 

55

What often happens with an anthropoid pelvis? 

Baby doesn't engage 

56

Describe the features of the android pelvis

  • Narrow forepelvis 
  • Convergent side walls
  • Forward inclination of the sacrum 
  • Narrow subpubic arch

 

57

Where is the platypelloid pelvis often seen?

In African populations 

58

What often happens with platypelloid pelvis? 

Don't get engagement until very late in labour 

59

Describe the features of the platypelloid pelvis

  • AP diameter narrow
  • Forepelvis straight
  • Side walls wide
  • Inclination of sacrum narrow
  • Subpubic arch wide 

60

What happens in pelvimetry? 

Do an x-ray to determine measurements of pelvis

61

Why isn't pelvimetry done any more? 

Not an accurate measurement beacsue cartilage relaxes, so may change

62

What are the ideal measurements in pelvimetry? 

  • Transverse diameter of inlet = 13.5cm 
  • Interspinous diameter = 10cm
  • Obstectrical diameter = 10.5cm

 

  •  

63

What are the potential presentations? 

  • Vertex
  • Sinciput
  • Brow
  • Face

 

64

What is the presenting diameter in vertex presentation? 

9.5cm (suboccipitobregmatic) 

65

What position is the baby in with vertex presentation? 

Chin on chest, smallest diameter coming out through pelvis

66

What is the presenting diameter in a sinciput presentation? 

10cm (suboccipitofrontal) 

67

What is the presentating diameter in brow presentation? 

13.8cm (mentovertical) 

68

What is the presenting diameter in face presentation? 

9.5cm (submentobregmatic) 

69

What is the result of the 9.5cm presenting diameter with face presentation? 

Can be delivered vaginally, because same as vertex presentation 

70

What soft tissues constitute the passageway in labour? 

  • Cervix
  • Vagina
  • Perineum 

 

71

When may the cervix cause problems with delivery? 

If have had treatment for abnormal smear, can have scarring and stenosis

72

When may the vagina cause problems with delivery? 

Polyps/masses 

73

What may be necessary when the perineum stops the head from crowning? 

May need epistiotomy 

74

What changes to the pelvic floor occur during labour? 

  • Stretching of fibres of levator ani 
  • Thinning of central portion of the perineum to almost transparent membranous structure 

 

75

What 'passenger' factors may cause problems with labour? 

  • Size
  • Number
  • Position

76

What may cause a big fetus? 

Gestational diabetes 

77

Why can number of fetuses cause problems with labour? 

More fetuses = more likely to be breech

78

What aspects of fetal position can cause problems in labour? 

  • Presentation
  • Lie 

 

79

What is the ideal lie for labour? 

Longitudinal 

80

What lie may cause problems in labour? 

Transverse 

81

What can happen when a fetus has a transverse lie? 

Can cause umbilical cord prolapse 

82

What happens when there is an umbilical cord prolapse? 

The cord can go into spasm, stopping oxygen going to the baby 

83

What happens when a mother is found to have a transverse lie? 

They are usually admitted at 37 weeks, and if not stabalised by term, C-section

84

What are the potential attitudes of the fetus? 

  • Flexion - back of head facing canal 
  • Extension - face to canal

85

What are the types of breech presentation? 

  • Frank breech
  • Full breech
  • Single footling breech

86

What position is the fetus in with a Frank breech? 

Knees straight, buttocks to canal 

87

What position is the fetus in with a full breech? 

Knees bent 

88

What needs to be done with a single footling breech? 

C-section

89

Why is a C-section needed with a single-footling breech? 

Risk of cord prolapse 

90

What does the first stage of labour constitute? 

The interval between the onset of labour and full cervical dilation 

91

What are the phases of the first stage of labour? 

  • Latent phase
  • Active phase 

 

92

What happens in the latent phase of the first stage of labour? 

Onset of labour with slow cervical dilation to 4cm

93

How long does the latent phase of the first stage of labour take? 

Variable duration - can take days 

94

What happens in the active phase of the first stage of labour? 

Faster rate of cervical change, 1-1.2 cm/hour and regular uterine contractions 

95

When is someone considered to be in the second stage of labour? 

Once they are 10cm dilated 

96

What happens once a person is fully dilated? 

Wait an hour to allow contractions to push the baby down, and then push for one hour 

97

Why is a woman only told to push for one hour? 

Any longer would be very exhausted 

98

What % of maternal mortality is due to obstructed labour? 

10%

99

What can result from obstructed labour? 

  • Death of fetus 
  • Rupture of uterus 

 

100

What can be done in obstructed labour? 

  • C-section
  • Operative delivery 

 

101

What kind of incision is used in a caesarean section? 

Transverse suprapubic 

102

What is required in addition to incision in a C-section? 

Hand pushing to act as contractions 

103

What can be used in an operative delivery? 

  • Forceps
  • Vacuum extraction

 

 

104

When are forceps useful? 

When the baby is in the wrong position - can rotate and delivery 

105

When does the 3rd stage of labour commence? 

When there is completed birth of the baby 

106

When does the 3rd stage of labour end? 

With the complete expulsion of the placenta and membranes 

107

How long does the 3rd stage of labour last? 

Usually between 5 and 15 minutes, but any period up to 1 hour may be considered within normal limits 

108

What happens if the placenta is not delivered within an hour? 

Take to theatre 

109

Why must a patient be taken to theatre if placenta not delivered within 1 hour? 

Risk of infection or heavy bleeding 

110

What happens to the size of the uterus after the baby is born? 

There is a marked reduction 

111

Why is there a marked reduction in the size of the uterus after the baby is born? 

Due to powerful contraction and retraction (ongoing) 

112

What happens to the placenta as a result in the reduction in size of the uterus after the baby is born? 

It is reduced

113

By how much is the size of the placenta reduced due to the reduction in size of the uterus after the baby is born? 

Can be up to 1/2 before seperation begins 

114

What is the effect of uterine contraction on the post-birth placenta? 

Inelastic placenta is squeexed, and peels away 

115

What happens to the blood supply to the placenta after birth? 

  • Blood in intervillous space forced back into veins of spongy layer of decidua basalis.
  • Veins become tense and congested, and kept under pressure by underlying muscle of uterus 
  • Blood can't drain back into the maternal bloodstream because the uterus has retracted and doesn't allow it 

 

116

What are the signs that the placenta has seperated? 

  • Bleeding
  • Fundus retracted

 

117

What can happen if the midwife pulls on the cord before the placenta is fully seperated? 

Can get prolapse of the uterus

 

 

118

What is the normal blood flow to the placenta site? 

500-800ml/minute (10-15% of cardiac output) 

119

What is critical for minimising blood loss in women who have just given birth?

Normal physiological processes

120

When may there be lots of bleeding after giving birth? 

If no uterine contractions 

121

What can be given to a women to get uterus contracting after giving birth to prevent bleeding? 

Give syntometrine

122

What does syntometrine consist of? 

  • Oxytocin
  • Ergometrine

123

What is the effect of the oxytocin in syntrometrine? 

Causes uterine contractions within seconds (short term) 

124

What is the effect of the ergometrine in syntrometrine? 

More sustained tonic contraction

125

What is the advantage of syntrometrine? 

Shown to produce significant reduction in maternal death 

126

What physiological processes control bleeding in women who have just given birth? 

  • Powerful contraction/retraction of uterus, especially action of interlacing muscle fibres which constrict blood vessels running through myometrium 
  • Pressure exerted on placental site by walls of contracted uterus 
  • Blood clotting mechanism 

 

127

When does pressure exerted on placenta walls by sides of the contracted uterus control bleeding? 

After placenta and membranes have been delivered