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Flashcards in Week 10 - Partuition Deck (45)
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Define partuition

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


When is delivery classsed as pre-term?

-Befre 36 weeks


When is delivery classed as post-term?

-After 42 weeks


When does the uterus become palpable in pregnancy?

-12 Weeks


When does the uterus reach umbilicus during pregnancy?

-20 Weeks


When does the uterus reach the xiphisternum during pregnancy?

-36 Weeks


Why would a nurse weight the placenta after delivery?

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


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

-Fetal head has moved into pelvic inlet


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

-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


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

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


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

-Breech (buttocks or foot)


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



What is the average size of the pelvic inlet?



What can increase the size of the pelvic inlet?

-Softening of the ligaments by MMP2 and MMP9


Briefly, what is the first stage of labour?

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


What is cervical ripening?

-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


What triggers cervical ripening?

-Prostaglandins (E2 and F2x)


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

-Thin the cervix (effacement) and then dilate it


What happens to the myometrium during pregnancy?

-Thickens due to increased cell size and glycogen deposition


What generates the force in uterine smooth muscle cells?

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


What allows the smooth muscle to all contract unanimously?

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


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

-Cells which can spontaneously depolarise and generate action potentials
-Allows the myometrium to always be spontaneously motile


Describe the contractions in early pregnancy

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


Describe how the amplitude and frequency of contractions changes throughout pregnancy

-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


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



What is the major producer of prostaglandins throughout preganancy?



What controls the release of prostaglandins from the endometrium?

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


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

-Fall in prgesterone


How does oxytocin exert its effects on the endometrium?

-Binds to receptors on smooth muscle cells


What increases the endometrial sensitivity to oxytocin?

-Increase in oestrogen:progesterone ratio