HD: PBL 2 (Normal Pregnancy and Labour) Flashcards
What are antenatal screening tests?
System which assesses and reduced the risk of harm to the motherand baby during the pregnancy
What is involved in maternal well-being tests?
Weight, BP, urinalysis (for protein, blood and glucose), ultrasound, blood group and Rhesus group, screening for antibodies, full blood count, rubella, VDRL (syphilis test), hepatitis B and HIV screening
What is involved in foetal well-being tests?
Foetal ultrasound to check viability, number, growth and normal anatomy. Serum screening (blood test) and nuchal scan for Down’s syndrome. Cardiotocography in late pregnancu
Describe the programme/time-line of antenatal screening
8 weeks gestation - confirmation of pregnancy at GP
12-14 weeks - first hospital visit
GENERALLY: seen by midwife/obstetrician every 4 weeks until 28 weeks, then every 2 weeks between 28-36 weeks, then every week thereafter
Describe the normal physiological changes to the cardiovascular system during pregnancy
Cardiac output increases in first trimester, increased blood volume, heart rate and decreased diastolic blood pressure (vasodilation decreases peripheral vascular resistance)
Why can lying supine cause maternal hypotension and why may this cause dizziness and fainting?
There is compression of the vena cava due to the gravid uterus which significantly reduces venous return to the heart and consequently reduces cardiac output –> reduced perfusion to the head and neck area –> dizziness and fainting
Why does diastolic pressure decrease in pregnancy?
Placenta acts as AV shunt, there is also peripheral vasodilating factors such as oestrogen and progesterone as well as increased endothelial synthesis and prostaglandins (E2) and prostacyclins
Why is leg oedema often present in pregnancy?
Venous pressure in the legs is increased during pregnancy due to mechanical obstruction by the uterus and its contents as well as the high pressure of venous outflow from the uterus therefore the rise in venous pressure with the fall of colloid osmotic pressure in the blood results in oedema (more fluid flowing into cells and ECF)
Would a fall onto the stomach in pregnancy damage the foetus?
Unlikely due to the cushioning provided by the uterus and amniotic fluid
What is the Ferguson reflex?
This reflex is triggered when the foetal presenting part impinges on the ripened cervix, this causes a release of oxytocin from the posterior pituitary which binds to receptors in the myometrium and causes the muscle fibres to contract
When is labour diagnosed?
When regular painful uterine contractions effect progressive cervical dilation
What are the three stages of labour?
Dilation of cervix from 0-10cm (uterine contractions), foetal expulsion and placental expulsion
How does cardiac output change during labour?
Increases due to autotransfusion from the contracting uterus
Describe the first stage of labour
Cervix dilates at rate greater than 1cm/hour and normal Braxton-Hicks contractions become painful, rhythmic contractions every 2-3 minutes –> myometrial fibres contract and retract
Describe the second stage of labour
Contractions supplemented by voluntary contraction of abdominal muscles and fixing of diaphragm (increase in intra-abdominal pressure) and the foetus is delivered
