Obs Physiology

Question 1

Role of Human Chorionic Gonadotrophin in pregnancy

Answer 1

Prevents corpus luteum degradation so that the CL can produce progestins until the placenta is formed.

Question 2

Role of Progesterone in pregnancy

Answer 2

Source = corpus luteum then placenta.
Prepares endometrium and uterus for implantation by:
1) Proliferation, vascularisation and differentiation of endometrial stroma.
2)Promotes endometrial quiescence.
3) Increase maternal ventilation.
4) Promotes glucose deposition in fat stores.

Question 3

Role of Oestrogen in pregnancy

Answer 3

Source = ovary then placenta.
Facilitates progesterone action by increasing progesterone receptors at endometrium.
Indicator of fetal wellbeing during pregnancy.

Question 4

IgA in pregnancy

Answer 4

Secreted in breast milk

Question 5

IgE in pregnancy

Answer 5

Mast cells, used in anaphylaxis

Question 6

IgG in pregnancy

Answer 6

Only antibody able to cross placenta. Role in Rhesus disease with IgM.
Starts to cross at 16 weeks but majority is acquried in last 4 weeks.

Question 7

Immunology of pregnancy

Answer 7

Increase in both T helper 1 and 2 cells but bias towards Th2. Trophoblast has non-immunogenic interface with mother.

Question 8

Vascular changes at the uterus in pregnancy

Answer 8

Extra-Villus Trophoblast invade and remodel maternal spiral arteries. Invading chords form Primary villi which branch to form Secondary villi and then Free-floating villi. Penetrate to inner third of myometrium via decidua.

Question 9

Maternal adaptations at the cervix

Answer 9

Increased vascularity
Reduction in collagen
Increased mucus secretions via gland hypertrophy

Question 10

Maternal adaptations of the CV system

Answer 10

Increase cardiac output
Increase heart rate
Decrease in total peripheral resistance and decrease in blood pressure.
Increase red cell mass
Blood pressure initially falls and then rises in second half of pregnancy.

Question 11

Maternal adaptations in the resp system

Answer 11

Lower maternal PaCO2 to allow better gas exchange with fetus.

Question 12

Nutrients in pregnancy

Answer 12

Glucose main fatal energy substrate.

Hyperlipidaemia state for mother.

Question 13

Thyroid function in pregnancy

Answer 13

Increases

Question 14

Glomerular filtration rate in pregnancy

Answer 14

Increases

Question 15

What maternal hormones are suppressed by placenta hormones

Answer 15

growth hormone, LH and FSH

Question 16

How does glucose cross the placenta

Answer 16

Facilitated diffusion

Question 17

Examples of molecules which cross placenta via simple diffusion

Answer 17

Ketones, urea.

Question 18

Examples of molecules which cross placenta via active transport

Answer 18

Amino acids, water soluble vitamins.

Question 19

Early pregnancy maternal glucose levels

Answer 19

Post-prandial levels are low

Question 20

Late pregnancy maternal glucose levels

Answer 20

Post-prandial levels are high

Question 21

Stages of labour

Answer 21

First stage = onset of labour to fully dilated cervix (10cm). Includes latent and active phase. Latent = irregular contractions, ‘show’, cervix effaces, to 3cm dilated. Active = dilation over 4cm to fully dilated, regular contractions, engagement of fetus’ presenting part.
Second stage = from full dilation to fetus is delivered. Passive stage until head reaches pelvic floor and desire for mum to push commences, active stage with pushing from mum.
Third stage = from fetal delivery to passing of placenta and membranes.

Question 22

Features of labour onset

Answer 22

Painful, regular contractions
‘Show’ of mucus plug.
Cervix dilates (3cm) and effacement
Rupture of membranes can occur but is not defining feature.

Question 23

Braxton Hicks contractions

Answer 23

Painless, intermittent catering contractions before labour onset.

Question 24

3 factors which determine progress in labour

Answer 24

Passage - bony pelvis and resistance by soft tissue
Power - maternal uterine contraction force
Passenger - fetus

Question 25

Cervical effacement

Answer 25

Cervical ripening = thinning of cervix and shortening as muscle fibres retract. Accompanied by dilation. Caused by raised COX-2 levels.

Question 26

Stages of fetal descend in labour

Answer 26

``` Engagement Descent Flexion Internal rotation External rotation Restitution Lateral rotation ```

Question 27

Types of cephalic presentation

Answer 27

``` Vertex/crown (normal) Sinciput (forehead first) Brow Face Chin ```

Question 28

Types of breech presentation

Answer 28

Complete Footling Frank

Question 29

Types of vertex presentation

Answer 29

According to position of occiput. Left, right or transverse? Anterior or posterior? Best for fitting through pelvis is occiput-anterior and is mostly commonly left.

Question 30

Endocrinology of labour

Answer 30

- Progesterone synthesis decreases due to corticotropin-releasing hormone. Oestrogen levels also drop. - Ferguson's reflex from stretched myometrium triggers oxytocin release from posterior pituitary gland. Causes smooth muscle contractions. - Prostaglandins increase in labour to aid contractions via increasing myocyte contractility, ripen cervix and vasodilator small cervical vessels.

Question 31

Trimesters

Answer 31

``` 1 = 0 until 12+6 2 = 13+0 until 28+6 3 = 28+6 until birth/40 ```

Question 32

Hb in pregnancy

Answer 32

Physiological anaemia (low Hb), but increase red cell volume

Question 33

4 functions of the placenta

Answer 33

Gas exchange Endocrine (betahCG, progesterone etc) Nutrient and waste product exchange Barrier for infection

Question 34

Non-worrying murmur in pregnancy woman

Answer 34

Ejection systolic murmur

Question 35

Length of 3rd stage of labour

Answer 35

5-30 mins, over 30 mins increases PPH risk.

Question 36

Rate of dilation in active first stage of labour

Answer 36

0.5-1.0 cm/hour. Nulliparous = 1.2cm/hr and multiparous 1.5cm/hr. If active first stage is over 2hrs look for cause.

Question 37

Length of second stage of labour

Answer 37

Consider interventions if >2hrs for a nulliparous woman >1hr for a multiparous woman

Question 38

What can you use to track labour progress

Answer 38

Partogram

Question 39

Pattern of rise and fall of human chorionic gonadotrophin hormone

Answer 39

Detectable 8days after conception. Levels double every 48hrs in the first weeks of pregnancy. Reach peak at 10weeks of 80,000mIU/ml and then fall to 10,000mIU/ml for rest of pregnancy.

Question 40

Role of human placental lactogen hormone in pregnancy?

Answer 40

Mobilise glucose from fat reserves. Increase blood glucose levels. encourage mammary glands to become milk secreting tissues.

Question 41

Surfactant production by fetus

Answer 41

24 weeks

Question 42

When does the fetal heart start beating

Answer 42

4-5 weeks

Question 43

Discuss fetal haemoglobin and the changes on the oxygen saturation curve

Answer 43

HbF has higher affinity to oxygen than HbA (adult). This allows the oxygen in the mothers blood to transfer down to the fetus' haemoglobin which has a stronger attraction to the oxygen. HbA starts to be created at about 32-34 weeks. LEFT SHIFT ON CURVE