Flashcards in Week 10 - Partuition Deck (45)
-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?
When does the uterus reach umbilicus during pregnancy?
When does the uterus reach the xiphisternum during pregnancy?
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?
(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