L15 - Pregnancy and Birth COPY

Question 1

INITIATION OF LABOUR

i) what part of the maternal brain is stimulated by factors from the foetal hypothalamus?
ii) what do the foetal adrenals secrete?
iii) which hormone promoting labour increases and which hormone promoting pregnancy decreases?
iv) what does the maternal post pit secrete? what does the decidua (lining of uterus) release? what do these two events cause?
v) what causes mech stimulation of the uterus? what happens to the cervix?

Answer 1

i) ant pit of mother is stim by factors from foetal HT
ii) foetal adrenals secrete cortisol
iii) oestrogen increases and progesterone decreases

iv) maternal post pit secretes oxytocin and decidua releases prostaglandinds
- this creates uterine contractions

v) mech stim of uterus and cervix by overstretching and pressure from the babies head
- cervix shortens and dilates

Question 2

LATENT PHASE OF LABOUR

i) what does the cervix soften and shorten in response to?
ii) which two mediators cause uterine contractions?
iii) what is the intensity of contractions in this phase?

Answer 2

i) cervix soften and shortens in response to prostaglandins
ii) oxytocin and prostaglandins cause uterine contractions
iii) contraction intensity varies throughout this stage

Question 3

EFFACEMENT OF THE CERVIX

i) what is the appearance of the cervix before labour starts? what % effacement is this?
ii) what happens to the cervical os at complete effacement?

Answer 3

i) cervix is long before labour starts
- 0% effacement

ii) complete effacement = cervical os dilates

Question 4

DIAGNOSIS OF ACTIVE LABOUR

i) how often are contractions assessed? what is their character?
ii) what is the level of cervical effacement?
iii) how many cms will the cervix be dilated? how is this assessed?

Answer 4

i) assess every 10 min
- contractions are regular and painful

ii) full cervical effacement

iii) cervix will be dilated 4cm or more
- assess digitally on a vaginal exam

Question 5

ACTIVE/FIRST AND SECOND STAGES OF LABOUR

i) what is the average amount for the cervix to dilate per hour?
ii) what is the descent of the foetal head measured in relation to? (2)
iii) when is second stage of labour established?
iv) what happens during the second stage?

Answer 5

i) cervix dilates at 0.5cm per hour
ii) descent of foetal head is measured in relation to the ischial spines and pelvic brim
iii) second stage established when cervix is fully dilated
iv) baby is pushed out

Question 6

PELVIC INLET AND OUTLET

i) what shape is the pelvic brim?
ii) what is the approx transverse diameter of the pelvis? what happens to this as the foetus descends into the pelvis?
iii) which way does the foetal head rotate as it pushes through? what happens to the chin?
iv) which three diamters are in the pelvic outlet?
v) what happens to the coccyx during birth?

Answer 6

i) oval apart from at the promontory
ii) TV diam is around 13cm and is decreases as foetus desc into pelvis
iii) fetal head rotates antero posterior and the chin flexes
iv) outlet = AP, oblique and TV
v) coccyx is deflected backwards to make space

Question 7

FOETAL SKULL

i) which part of the skull usually presents anteriorly at the outlet of the pelvis?
ii) which part is the narrowest? what is the widest part?
iii) what shape is the anterior fontanelle? how many sutures intersect to form it? when does it close?
iv) what shape is the posterior fontantelle? how many sutures join to form it? when does it close?
v) why does the occiput rotate to an anterior position? what may happen if it doesnt do this?

Answer 7

i) occiput
ii) suboccipitobregmatic diam is narrowest and biparietal diameter is the widest part

iii) ant fontanelle is diamond shaped formed by joining of four sutures
- closes at 18 months

iv) post fontanelle is Y shaped and formed by 3 sutures
- closes at 6-8 weeks

v) occiput rotates to adapt to narrow space at the outlet
- may be harder to birth if it doesnt do this

Question 8

label the parts of the foetal skull

Answer 8

A = occiput

B = suboccipitobregmatic diam (narrowest)

C = posterior fontanelle

D = biparietal diameter (widest)

E = anterior fontanelle aka bregma

Question 9

MECHANISM OF BIRTH

i) in what plane does the head enter the pelvis?
ii) what does the foetus do with its head as it descends?
iii) what happens when the foetus reaches the pelvic floor? (what does foetus and mother do) (2)
iv) what diameter of the pelvis do the shoulders rotate into?
v) what type of pressure on the babys head delivers the anterior shoulder? what direction of lateral flexion delivers the posterior shoulder?

Answer 9

i) transverse plane
ii) foetus flexes the head as it descends
iii) when foetus reaches pelvic floor the mother pushes and the baby rotates to occipital anterior position
iv) shoulders rotate into AP diameter of pelvis
v) downward pressure delivers ant shoulder and upward lateral flexion delivers posterior shoulder

Question 10

THIRD STAGE OF LABOUR

i) what does it involve the delivery of?
ii) what is the normal estimated blood loss? how much does maternal circulation increase during birth to allow for this?
iii) what hormone is given in active management? what does this cause and therefore allow? (3) what does it decrease the risk of?

Answer 10

i) the placenta

ii) 300-500ml of blood
- maternal circulation increases by 50% in birth

iii) oxytocin can be given to cause uterine contractions which allows contraction of placental bed and delivery of the placenta
- decreases risk of post partum haemmorhage

Question 11

FOETAL MONITORING IN LABOUR

i) what is this used to detect?
ii) name three ways to intermittent auscultate
iii) how often is intermittent auscultation of the heart used in first stage of labour? how often in second stage? what would be used if any abnormality was found?
iv) what gives a continous print out of foetal heart rate and contractions using abdo US? is this diagnostic?
v) name another way foetal heart rate may be monitored

Answer 11

i) detect foetal hypoxia and deliver the baby if needed
ii) doppler/ear trumpet, cardiotocograph or foetal blood sample

iii) first stage = every 15 min before and after a contraction
second stage = every 5 mins
- find abnormality = use cardiotocograph (CTG)

iv) cardiotocograph gives foetal heart rate
- not diagnostic, just screening tool

v) also measure foetal heart rate using a foetal scalp electrode (not often used)

Question 12

FOETAL BLOOD SAMPLING

i) in what situation is a CTG highly sensitive? in what situation is it poorly specific?
ii) what does use of CTG leads to an increase?
iii) what are CTG readings checked with?
iv) how is a foetal blood sample taken? name two things that can be sampled
v) name three contraindications of foetal blood sampling

Answer 12

i) CTG is highly sensitive if baby is ok but poorly specific if baby is hypoxic
ii) CTG leads to increase in caesarians if heart abnorm
iii) check CTG readings with foetal blood sample

iv) take blood sample with a stab on the foetal scalp and collect blood via a glass pipette
- can give info about pH and base excess

v) contraindics = infection such as HIV/Hep B, foetal blood disorder and premature (<32wks)