Antenatal care & screening

Question 1

Are palpitations a common complaint in pregnancy?

Answer 1

Cardiac output (CO) increases by 30-50%

CO = SV x HR, heart rate increases from 70-90bpm

At Term blood flow to the uterus must exceed 1L/min

Question 2

When in pregnancy does BP drop?

Answer 2

In the second trimester

Expansion of the uteroplacental circulation

A fall in SVR

A reduction in blood viscosity

A reduction in sensitivity to angiotensin

BP usually returns to normal in the third trimester

Question 3

Why are UTIs in pregnancy important to treat?

Answer 3

Can be associated with preterm labour

(There is an increase in urinary stasis & Hydronephrosis is physiological in the third trimester and makes pyelonephritis more common)

Question 4

Why does an anaemia occur in preg?

Answer 4

Plasma volume increases by about 50% and RBC mass by about 25%
This results in a drop in haemoglobin by dilution from 133-121g/L

Iron requirements are increased by 1g during pregnancy

Platelet count falls by dilution

Question 5

Progesterone acts centrally to reduce CO2: How else is resp affected in preg?

Answer 5

Progesterone acts centrally to reduce CO2

Increase:
Tidal volume
Respiratory rate
Plasma pH
O2 consumption increases by 20%

Plasma PO2 is unchanged

Hyperaemia of respiratory mucous membranes

Question 6

How is the GI system affected in preg?

Answer 6

Oesophageal peristalsis is reduced

Gastric emptying slows

Cardiac sphincter relaxes

GI motility is reduced due to
INCREASED progesterone and REDUCED motilin

Question 7

What supplements should be started pre-preg?

Answer 7

Folic acid 400 mcg standard dose or 5mg high dose

Vitamin D 10mcg daily

Question 8

Does thyroxine demand increase in preg?

Answer 8

Yes, therefore if taking it doses need to be increased (hypothyroidism)

Question 9

What should be checked in antenatal examination?

Answer 9

Routine enquiry
Feeling well
Feeling fetal movements
(after 20 weeks)

Blood Pressure (Detect evolving hypertension)

Urinalysis

Abdo palpation (SFH, size, liquor volume)

Determine fetal presentation

Listen to fetal heart

Question 10

What infection screening is offered?

Answer 10

Hepatitis B
- If infected can provide passive and active immunisation for baby

Syphilis
- Easily treated with Penicillin

HIV
- Maternal treatment and careful planning reduces vertical transmission

MSSU-Urinary tract infection

Question 11

What are all women screened for?

Answer 11

All pregnant women are screened for Rubella, Hepatitis B, Syphilis, and HIV as part of routine ANC. Consent is required for all testing.

Question 12

What is offered to all Rh negative women?

Answer 12

Anti D IgG is offered to all Rh negative women both prophylactically and after potentially sensitising events.

Question 13

What is screened for at 12 & 28 weeks gestation?

Answer 13

Iron deficiency anaemia

Isoimmunisation
- Rhesus disease
- Anti-c, Anti-Kell

Question 14

When is first trimester screening carried out and what does it use?

Answer 14

Carried out at 10-14 weeks gestation

Uses maternal risk factors, serum B-human chorionic gonadotrophin (B-hCG) and pregnancy associated plasma protein A (PAPP-A) and fetal nuchal translucency (NT) measurement

Question 15

What does nuchal translucency show?

Answer 15

Nuchal translucency increases with gestational age
and the incidence of chromosomal and other
abnormalities is related to the size, rather than the
appearance of NT.

Question 16

When is further testing offered?

Answer 16

Further testing is offered if risk of Down’s syndrome is >1 in 150

Options:
CVS
Amniocentesis
Non-invasive Prenatal testing

Question 17

How is non invasive prenatal testing done?

Answer 17

Maternal blood taken
- Can detect fetal cell free DNA released from the placenta
- No risk of miscarriage

Not diagnostic, so if gives a high risk result, parents are offered CVS/amniocentesis

Question 18

Amniocentesis can be done from … weeks onwards

Answer 18

15

Question 19

How is screening for a neural tube defect done?

Answer 19

Not routinely offered since introduction of first trimester screening

Personal or FH of NTD are at increased risk
- Should be advised to take 5mg folic acid to reduce risk

First trimester USS to detect anencephaly and sometimes spina bifida (variants of NTD)

2nd trimester biochemical screening
- Carried out if not able to get NT measurement
- Maternal serum is tested for alpha fetoprotein

Second trimester (20wk) ultrasound will detect >90% of NTD

Question 20

What USS sign can indicate Spina bifida?

Answer 20

Banana sign

Head signs often detected first

Question 21

What is the role of the second trimester USS?

Answer 21

To detect fetal abnormality

This is a good screening test for major structural abnormalities but a poor test for chromosomal abnormalities