Week 10 - Partuition Flashcards Preview

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Flashcards in Week 10 - Partuition Deck (45)
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1
Q

Define partuition

A

-Transition from pregnant state to non-pregnant state at the end of gestation due to expulsion of products after 24 weeks

2
Q

When is delivery classsed as pre-term?

A

-Befre 36 weeks

3
Q

When is delivery classed as post-term?

A

-After 42 weeks

4
Q

When does the uterus become palpable in pregnancy?

A

-12 Weeks

5
Q

When does the uterus reach umbilicus during pregnancy?

A

-20 Weeks

6
Q

When does the uterus reach the xiphisternum during pregnancy?

A

-36 Weeks

7
Q

Why would a nurse weight the placenta after delivery?

A

-Often weighs the same as the baby so measures it to ensure all the placenta has been delivered

8
Q

Why does the fundus move back towards the pubic symphysis at term?

A

-Fetal head has moved into pelvic inlet

9
Q

What 3 positional factors need to be assessed towards the end of pregnancy?

A
  • Lie -> Relationship of the long axis of the baby to the uterus
  • Presentation -> Which part of the fetus is adjacent to the pelvic inlet
  • Vertex -> Relationship of fetus along its axis in relation to presenting part
10
Q

What is the most common positions of lie, presentation and vertex of a baby?

A
  • Lie -> Normally longitudinal and fetus flexed
  • Presentation -> Normally the head
  • Vertex -> minimal diameter between presenting part and pelvic inlet
11
Q

Give some abnormal presentations of the fetus at the end of pregnancy

A
  • Breech (buttocks or foot)
  • Brow
  • Shoulder
12
Q

In normal presentation, what is the average diameter of the head?

A

-9.5cm

13
Q

What is the average size of the pelvic inlet?

A

-11cm

14
Q

What can increase the size of the pelvic inlet?

A

-Softening of the ligaments by MMP2 and MMP9

15
Q

Briefly, what is the first stage of labour?

A

-Creation of the birth canal by expansion of the soft tissues (Cervix, uterus and vagina) and cervical ripening

16
Q

What is cervical ripening?

A
  • Process in the first stage of labour where the thick tough cervical collagen is softened
  • Involves reduction in collagen through enzymatic degradation, increases in GAGs in order to separate strands and reduce aggregation, increase in hyaluronic acid to draw in water so tissues expand
17
Q

What triggers cervical ripening?

A

-Prostaglandins (E2 and F2x)

18
Q

What effect do contractions have in the first stage of labour?

A

-Thin the cervix (effacement) and then dilate it

19
Q

What happens to the myometrium during pregnancy?

A

-Thickens due to increased cell size and glycogen deposition

20
Q

What generates the force in uterine smooth muscle cells?

A

-Intracellular apparatus of actin and myosin triggered by an increase in intracellular calcium due to action potentials arriving at the cell membrane

21
Q

What allows the smooth muscle to all contract unanimously?

A

-Specialised gap junctions allows the action potential to spread from cell to cell allowing coordinated contractions of the myometrium

22
Q

What are pacemaker cells of the fundus? How is this beneficial?

A
  • Cells which can spontaneously depolarise and generate action potentials
  • Allows the myometrium to always be spontaneously motile
23
Q

Describe the contractions in early pregnancy

A

-Approximately every 30 mins or so but are of low amplitude so cannot be felt

24
Q

Describe how the amplitude and frequency of contractions changes throughout pregnancy

A
  • Frequency falls throughout pregnancy with an increase in amplitude
  • Can produce noticable ‘Braxton-Hicks’ contractions mid gestation
  • Onset of labour characterised by a sudden increase in apmplitude and frequency of contractions
25
Q

Which two hormones are indicated in the sudden onset of increased amplitude and frequency of contractions?

A
  • Prostaglandins

- Oxytocin

26
Q

What is the major producer of prostaglandins throughout preganancy?

A

-Endometrium

27
Q

What controls the release of prostaglandins from the endometrium?

A

-Oestrogen:Progesterone ratio
(low ratio = low synthesis, high ratio=high synthesis)
-Oxytocin

28
Q

During labour, what is suspected to causes an increase in prostaglandin synthesis and thus increased contractions?

A

-Fall in prgesterone

29
Q

How does oxytocin exert its effects on the endometrium?

A

-Binds to receptors on smooth muscle cells

30
Q

What increases the endometrial sensitivity to oxytocin?

A

-Increase in oestrogen:progesterone ratio

31
Q

What is the furgeson reflex? What is its purpose?

A
  • As contractions increase, sensory receptors in the cervix and vagina are stimulated. The excitation passes via afferent nerves to the hypothalmus which ultimately promotes oxytocin release
  • This enters a positive feedback cycle as increased oxytocin increases the frequency and force of contractions which further stimulates oxytocin release and so on
32
Q

What is oxytocin?

A

-A peptide hormone secreted from the posterior pituitary which lowers the threshold for action potentials to generate contraction of smooth muscle cells making contractions more frequent and forceful

33
Q

What is brachystasis?

A

-Muscle fibres contract more than they relax so gets progressively shorter, particuarly in the fundal region, therefore pushes the presenting part into the pelvic inlet and cervix

34
Q

Why does fetal oxygen reduce during labour?

A

-Forceful uterine contractions temporarily interrupt placental blood supply thus reducing o2 supply to fetus -> needs to be monitored to make sure not excessive

35
Q

What marks the end of the first stage of labour?

A

-Dilation of the cervix to 10cm

36
Q

Which stage of labour is the quickest?

A

-Second

37
Q

Describe the second stage of labour

A
  • Head flexes as it meets the pelvic floor
  • internal rotation
  • Descent
  • Crowning as head is delivered it rotates and extends back to original position
  • Shoulders rotate, followed by the head and the shoulders deliver followed by the rest of the body
38
Q

What marks the end of the second stage of labour?

A

-Delivery of the fetus

39
Q

Describe the 3rd stage of labour

A
  • After the fetus is removed there is a powerful contraction which separates the placenta from the uterus
  • Placenta and membranes expelled withing 10 minures
40
Q

Besides from delivery of the placenta, why is the powerful contraction of the third stage of labour crucial?

A

-Compress the blood vessels to reduced the bleeding of the uterus

41
Q

Whaat tirggers the fetus to take its first breatg?

A

-Environmental stimuli eg light, temperature change, noise, trauma

42
Q

Describe the vascular changes which occur in the fetus after delivery

A
  • First breath causes a dramatic fall in pulmoonary resistance which reduced pulmonary arterial pressure -> reduced pressure in RA lower than LA -> closure of foramen ovale
  • Rising arterial pO2 causes coontraction of smooth muscle in DA
  • As the umbilical cord is clamped, removal of placental supply causes the sphincter in DV constricts and DV closes
43
Q

What is the Apgar score?

A

-A system used to monitor the fetus after birt

44
Q

How can post-partuition haemmorhage be limited medically?

A
  • Fundal massage

- Oxytocic drug

45
Q

Why does labour need to be induced ~42+ weeks?

A

-Reducion in amniotic fluid is dangerous for baby