Week 3 - C - Antenatal care and screening in pregnancy (Down's screening & Pre-eclampsia prophylaxis also)

Question 1

The mothers health takes priority – so if the clinician has to end a pregnancy to save the mothers life that is what they will do

How many ultrasound scan are carried out in a non-complicated pregnancy and at what weeks?

Answer 1

2 ultrasound scans are carried out in a non-complicated pregnancy

The first occurs around 8-14 weeks - usually at week 12 (end of the first trimester)

The second scan occurs around week 18-20 weeks

Question 2

How long should folic acid be taken for?

Answer 2

Folic acid supplements should be taken whilst trying for pregnancy and up to 12 weeks of pregnancy to prevent neural tube defects - the neural tube forms the brain and spinal cord

Question 3

Normally in the booking visit for a pregnant women, an obstetrics history is taken before an examination is carried out

WHat are the components of the history?

Answer 3

Name, age, parity

• PC and HPC

History of present pregnancy
Past obstetrics history
Gynaecological history

• Past medical history and previous surgeries
• DHx and allergies
• FHx
• SHx
• Systematic enquiry

Question 4

Who usually carries out the booking visit?

After the history is taken, examination begins, height, weight, blood pressure of mother are all taken

What is examined?

Answer 4

Booking visit is usually carried out by the midwife but can be carried out by a doctor

In the examination, an abdominal examination of the mother is carried out

Question 5

What is gestational age measured from?

What day does it assume that ovulation takes place on?

Answer 5

Gestational age is the common term used during pregnancy to describe how far along the pregnancy is. It is measured in weeks, from the first day of the woman’s last menstrual cycle to the current date

Gestational Age is in weeks from the first day of the last menstrual period and assumes ovulation on day #14 of that cycle.

Question 6

What is the pregnancy (gestational age) calculator used to estimate the estimated due date of the pregnancy?
How does the calculation work?

Answer 6

The calculation is done using: Naegele’s Rule for Pregnancy

The calculation works by adding nine months and seven days to the first day of the Women’s LMP - this should be approx 40 weeks after the LMP

Question 7

A number of blood tests investigations are carried out for a women in antenatal care roughly around the time of the booking visit

What is screened for in the blood?

WHat is looked for in urinalysis?

Answer 7

In the blood - syphilis, sickle cell anaemia, thalasaemia, BBV, rhesus disease and haemoglobin count

• (syphilis and thalasaemia only in high risk patients)

Urinalysis - check for gestational diabetes, and pre-eclampsia

Question 8

What would be seen on urinalysis in a mother with pre-eclampsia?

Answer 8

over 300mg protein

Question 9

An ultrasound scan is carried out in the first trimester - roughly 12 weeks - to look for any foetal abnromalities

• Confirm viability
• Number of foetuses
• Estimate gestational age – explain the most accurate time/method
• Detect major structural anomalies that may be identified in early pregnancy

What number of ultrasound scans will detect a miscarriage?

Answer 9

1in5 scans at this time will pick up a miscarriage in the mother

Question 10

What does this USS show?

Answer 10

Shows twins

Question 11

What is the gestational age of the foetus by measured using?

Answer 11

The head circumference of the baby is used to try and measure the approximate gestational age of the baby

Question 12

Apart from foetal head circumference, what else can be used to give an approximate gestational age?

Answer 12

Can use the femur length, crown-heel lenght and biparietal diameter (the latter two are slightly more inaccurate)

Question 13

In follow up antenatal visits after the booking appointment, physical and mental health of the mother are checked and examination of the abdomen are regularly carried out

An early screening scan is carried out in the booking visit (initial ultrasoun here) to look for what abnormality?

Answer 13

Screens for any foetal anomaly eg Down’s syndrome

Question 14

The ultrasound scan screens for nuchal translucency and chorionicity

What is chorionicity? (ie monochronic twins or dichronic twins)

Answer 14

The chorionicity of twins. Twins can be either dichorionic or monochorionic:

• Dichorionic – each baby has a separate placenta and is inside a separate sac which has its own outer membrane, called a ‘chorion’.
• Monochorionic – the babies share a placenta and chorion (which means they are identical).

Question 15

Objectives of screening ultrasound:

• Reduction in perinatal mortality and morbidity
• Potential for in utero treatment
• Identification of conditions amenable to neonatal surgery

First trimester is the optimum time for down’s syndrome screening
How sensitive is the 1st trimester screening for DOwn’s syndrome?

Answer 15

1st trimester screening for Down’s syndrome is 90% sensitive

(clinodactyly - is a medical term describing the curvature of a digit )

Question 16

What is measured on the Down’s syndrome USS screening scan at 10–13weeks6days?

Answer 16

The nuchal translucnecy szie (basically thickness) (NT) is measured - this is the measure of skin thickness behind the foetal neck using ultrasound - greater thickness means a greater risk of Down’s syndrome

Question 17

The NT test is done in combination with measure free-bHCG and PAPP-A
This is known as the combined test - a different but similar testing is carried out in second trimester screening (better to screen earlier for accurate results)

What do the free-bHCG and PAPP-A stand for?
Should their levels be higher or lower in DOwns?

Answer 17

Nuchal transparency size - higher in a child with downs

free-bHCG free-beta human chorionic gonadotrophin - raised in a child with downs

PAPP-A - pregnancy associated plasma protein A- decreased in a child with Down’s

Question 18

What in the placenta produced b-HCG and PAPP-A?

Answer 18

It is the placental syncytiotrophoblasts that produce both b-human chorionic gonadotrophin and pregnancy associated plasma protein A

Question 19

If a woman books later in pregnancy (when nuchal translucency is not as accurate, or if it is not technically possible to measure it) the quadruple test can be taken.

When is the blood sample of the quadruple test able to be taken?

Answer 19

The blood smaple of this test can be taken between 15+0 weeks and 20+0 weeks

Question 20

What four markers are measured in the quadruple test?

Answer 20

Alfa-foeto protein

UNconjugated estradiol
b-HCG (free or total)
And

Inhibin A

Question 21

For both first and second trimester:

Incorporation of these measurements / results with maternal age and gestation to give a personal risk

What is measured in the combine test in 1st trimester?
What is measured in the quadruple test in 2nd trimester?

A risk greater than what requires frther investigation?

Answer 21

1st trimester

• Nuchal translucency size
• Free-bHCG
• PAPP-A

2nd trimester - 15-20 weeks

• Alfa-feto protein
• UNconjugated estradiol
• Free or total b-HCG
• Inhibin A

A risk greater than 1 in 250 warrants further investigation

Both tests take into account the mothers age

Question 22

Low AFP and high HCG greatly increase the risks of Down’s syndrome

What specific diagnostic tests can be carried out if the risk if greater than 1 in 250?

Answer 22

Amniocentesis or chorionic villus sampling

Question 23

Amniocentesis:

• Usually performed after 15 weeks

Chorionic villus sampling:

• Usually performed after 12 weeks

What is the miscarriage rate of both these procedures?

Answer 23

Amnicoentesis - miscarriage rate of 1%

Chorionic villus sampling - miscarriage rate of 2%

Question 24

When is screening for things like sickle cell anaemia and thalasaemia carried out?

Answer 24

Carried out based on ethnicity and therefore you are either high risk for not for the screening procedure

Question 25

What is given to rhesus negative mothers who have been exposed to rhesus positive blood of baby?

What antibodies is the treatment composed of?

Answer 25

Anti-D immunoglobulin

It is composed of IgG antibodies as they are able to cross the placenta (IgG is dimeric)

Question 26

When can Anti-D immunoglobulin be given to prevent sensitisation of the mothers blood?

Answer 26

Ideally given within 72 hours of expsorue but can be given up to 10 days after

Question 27

Where is the ideal site for Anti-D injection?

What are its attachment points?

Answer 27

Origin the anterior border and upper surface of the lateral third of the clavicle, acromion, spine of the scapula

Insertion deltoid tuberosity of humerus

Ideal site for adminsitration is the deltoid muscle

Question 28

Do you have new feelings and thoughs which you have never had before, which make you disturbed or anxious ?

Are you experiencing thoughts of suicide or harming yourself in violent ways ?

Are you feeling incompetent as a mother as though you cant cope or feeling distant or estranged

What is one of the major causes of death of feotus in pregnancy?

Answer 28

The maternal mental health

Question 29

In women with more than one moderate risk factor for pre-eclapmsia

What is the advise prophylaxis treatment from 12 weeks of pregnancy?

Answer 29

Pregnant women at increased risk of pre-eclampsia at the booking appointment are offered a prescription of 75 mg of aspirin to take daily from 12 weeks until birth.