Antenatal Care & Screening Flashcards
What five general lifestyle advice to we give pregnant women?
Folic Acid Supplements
Vitamin D Supplements
Alcohol Cessation
Smoking Cessation
Medication Alteration
How long should folic acid supplements ideally be taken prior to pregnancy?
Three months
Why do we promote pregnant patients taking folic acid supplements?
They decrease the risk of the baby developing neural tube defects
What dose of folic acid supplements are recommended?
400mcg daily
In what three patient groups is a dose of folic acid 5mg daily recommended?
Those who have a BMI > 30
Those who take valproate for epilepsy
Those who have had a previous child with spina bifida
What dose of vitamin D supplements is recommended in pregnant patients?
A dose of 10mcg daily throughout the whole pregnancy
Why is alcohol cessation recommended to pregnant patients?
Alcohol can cross the placenta, enter the foetus, and disrupt fetal development
Is there a safe level of alcohol in pregnancy?
No
Women are encouraged not to drink at all
What are the three complications of alcohol during pregnancy?
Miscarriage
Preterm Delivery
Fetal Alcohol Syndrome
What are the seven clinical features of fetal alcohol syndrome?
Microcephaly
Smooth Flat Philtrum
Short Palpebral Fissure
Thin Upper Lip
Learning Disability
Hearing & Vision Problems
Cerebral Palsy
What are the six complications that can arise due to smoking during pregnancy?
Fetal Growth Restriction
Sudden Infant Death Syndrome (SIDS)
Miscarriage
Stillbirth
Preterm Delivery
Pre-Eclampsia
What is the first pregnancy appointment called? When does it take place?
Booking clinic
10 weeks gestation
What four investigations take place at the booking clinic?
Antenatal Examination
Bloods
Blood Pressure
Urinalysis
What two measurements are taken during the antenatal examination in the booking clinic?
Symphyseal Fundal Height (SFH)
Fetal Presentation
What is the SFH?
This is the distance between the pubic symphysis to the fundus of the uterus
What is the SFH used to measure?
This measurement is then plotted on a chart allowing us to measure the growth of the foetus and whether this is normal or not
In what two circumstances can the SFH measurement not be obtained?
High BMI
Uterine fibroids
Why is fetal presentation important?
If abnormal, it can have implications for delivery
What is offered when the baby remains in a breech presentation after 36 weeks?
External cephalic aversion
What is external cephalic aversion?
This is a procedure used to turn a fetus from a breech position into a vertex position before labour begins
What happens if an external cephalic version fails?
The baby will be delivered by elective c-section
What seven blood tests taken during the booking clinic?
FBC
Blood Group
Antibodies
Rhesus D Status
Alpha Fetoprotein
Infectious Disease Screening
Inherited Blood Disorder (Haemoglobinopathy) Screening
Why is a FBC conducted during the booking clinic?
To look for anaemia
What alpha fetoprotein level at the booking clinic indicates further investigation?
> 2MoM
What is rhesus?
It refers to various types of rhesus antigens on the surface of red blood cells
What is the most relevant antigen within the rhesus blood group system?
Rhesus-D antigen
How do we manage pregnant women who are rhesus-D positive?
There is no need for any additional treatment during pregnancy
Explain why rhesus-D negative pregnant women need to be managed
There is a possibility that her child will be rhesus positive.
It is likely that at some point during the pregnancy that the blood from the baby will find a way into the mother’s bloodstream.
When this happens, the baby’s red blood cells display the rhesus-D antigen.
The mother’s immune system will recognise these antigens as foreign and produce antibodies against them.
The mother has then become sensitised to rhesus-D antigens.
This sensitisation process doesn’t cause problems during the first pregnancy.
However, in subsequent pregnancies, the mother’s rhesus-D antibodies can cross the placenta into the fetus.
If that fetus is rhesus-D positive, these antibodies attach themselves to the red blood cells of the fetus and causes the immune system of the fetus to attack them.
The red blood cell destruction (haemolysis) caused by the antibodies of the mother is called haemolytic disease of the newborn.
How do we manage rhesus-D negative women during pregnancy?
All women are given intramuscular anti-D injections
How does anti-D medication work to prevent sensitisation?
It works by attaching to the rhesus-D antigens on the fetal red blood cells in the mother’s circulation, causing them to be destroyed
This prevents the mother’s immune system recognising the antigen and creating its own antibodies to the antigen
When do we give anti-d injections - three circumstances?
28 weeks’ gestation
Sensitisation events
At birth (if the baby’s blood group is found to be rhesus-positive)
What is the Kleihauer test?
It checks how much fetal blood has passed into the mother’s blood during a sensitisation event
When is the Kleihauer test conducted? Why?
It is used after any sensitising event past 20 weeks’ gestation
To assess whether further doses of anti-D are required
How is the Kleihauer test conducted?
This test involves adding acid to a sample of the mother’s blood
Fetal haemoglobin is naturally more resistant to acid, therefore it persists in response to the added acid, whilst the mother’s haemoglobin is destroyed
The number of cells still containing haemoglobin can then be calculated
What three infectious diseases are screened during the booking clinic? In which women do we screen these diseases?
Hepatitis B
HIV
Syphilis
This is part of the routine antenatal screening, which is recommended for every pregnancy
What two inherited blood disorders are screened during the booking clinic? In which women do we screen these diseases?
Sickle cell disease - only those that are at high risk are screened
Thalassaemia -all pregnant women are offered screening
Why is blood pressure measured at the booking clinic?
It is conducted to screen for hypertension
A hypertensive pregnancy can be indicative of pre-eclampsia
Why is a urinalysis investigation conducted at the booking clinic?
It is used to screen for excess protein and bacteria
This can then allow diagnosis of a UTI or pre-eclampsia
After the booking clinic what is the next pregnancy appointment? When is this conducted?
Dating scan
10-14 weeks
What investigation is conducted at the dating scan?
Ultrasound scan
What are the six things screened for at the dating scan?
It is used to check the baby’s heartbeat, growth and development
It is used to estimate the stage of the pregnancy and the due date
It confirms whether there is a multiple pregnancy
It allows screening for trisomy abnormalities. These screening tests only provide a risk of their baby being affected however cannot provide a confirmed diagnosis
It is used to measure the nuchal translucency (NT)
It screens for neural tube defects
What measurement is used to calculate the gestational age?
Crown rump length
What are the three types of trisomy abnormalities?
Down’s syndrome (trisomy 21)
Edward’s syndrome (trisomy 18)
Patau’s syndrome (trisomy 13)
Can screening for trisomy abnormalities confirm a diagnosis?
No, they can only estimate a risk
What is the first line antenatal screening for Down’s syndrome?
Combined test
At what gestation is the combined test conducted?
11-14 weeks gestation
What is the combined test?
It involves combining results from ultrasound and maternal blood tests
What does the ultrasound scan in the combined test measure?
Nuchal translucency
What is the nuchal translucency?
This is the sonographic appearance of a collection of fluid under the skin behind the fetal neck
What two things increase the nuchal translucency?
Gestational age
Chromosomal abnormalities
What nuchal translucency thickness is indicative of Down’s syndrome?
> 6mm
What investigation should be conducted when individuals have a high nuchal translucency and a low trisomy risk? Why?
Cardiac scan
This is due to fetal cardiac abnormalities are associated
What two maternal blood tests are included in the combined test?
Beta-Human Chorionic Gonadotrophin (beta-hCG)
Pregnancy-Associated Plasma Protein-A (PAPPA)
What beta-hCG result indicates a greater risk of Down’s syndrome?
Higher
What PAPPA result indicates a greater risk of Down’s syndrome?
Lower
When is the triple test conduced?
14-20 weeks gestation
This investigation is only conducted if it is not possible to obtain a nuchal translucency measurement or the patient is over 14 weeks pregnant
What three maternal blood tests are included in the triple test?
Beta-Human Chorionic Gonadotrophin (beta-hCG)
Alpha-Fetoprotein (AFP)
Serum Oestriol
What AFP result indicates a greater risk of Down’s syndrome?
Lower
What serum oestriol result indicates a greater risk of Down’s syndrome?
Lower
When is the quadruple test conducted?
14-20 weeks gestation
This investigation is only conducted if it is not possible to obtain a nuchal translucency measurement or the patient is over 14 weeks pregnant
What is the quadruple test?
It is identical to the triple test, but also includes maternal blood testing for inhibin-A
What inhibin-A result indicates a greater risk of Down’s syndrome?
Higher
What three investigations should be offered to individuals when individuals have a Down’s syndrome risk score greater than 1 in 150?
Non-Invasive Prenatal Testing
Chronic Villus Sampling (CVS)
Amniocentesis
What is the first line investigation used for high nuchal translucency?
Non-invasive prenatal testing
What is non-invasive prenatal testing?
It involves sampling maternal blood, which will contain fetal cell free DNA that has been released from the placenta
Does non-invasive prenatal screening carry a risk of miscarriage?
No
What happens if the risk of chromosomal abnormalities is determined low from non-invasive prenatal screening?
No further investigations are required
What happens if the risk of chromosomal abnormalities is determined high from non-invasive prenatal screening?
These parents are offered amniocentesis and chronic villus sampling to further investigate this
When is CVS conducted?
10-14 weeks gestation
What is CVS?
It involves a fine needle being guided through the abdomen to take a small sample of tissue from the placenta
The chromosomes from the placenta can be counted from the sample
What is the % risk of miscarriage with CVS?
1-2%
When is amniocentesis conducted?
15 weeks gestation
What is amniocentesis?
It involves a fine needle being guided through the abdomen to take a small sample of amniotic fluid
The chromosomes from the fluid can be counted from the sample
What is the % risk of miscarriage with amniocentesis?
1%
What is the routine screening test offered to women for Down’s syndrome?
Combined ultrasound/biochemical (CUB) investigation
What are the two types of neural tube defects?
Anencephaly
Spina Bifida
What is ancephaly?
It is characterised by an absence of cortical tissue and cranial vault
What are the three features of ancephaly on the dating scan?
The presence of no parenchymal tissue
A low crown-rump length
A “frog eye” appearance due to absent cranial bone and bulging orbits
What is spina bifida?
It is characterised by incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy
What are the three features of spina bifida on the dating scan?
The presence of dorsal ossification centres or lateral pedicles are being splayed apart
The lemon sign, which is when the shape of the fetal skull appears flattened and inwardly scalloped
The banana sign, which is the appearance of the cerebellum wrapped around the medulla
What next pregnancy appointment occurs after the dating scan?
Anomaly scan
When is the anomaly scan carried out?
18 and 21 weeks gestation
What does the anomaly scan screen for?
Neural tube defects
What are the three neural tube defects screened for on the anomaly scan?
Hypoplastic Left Heart
Exomphalos
Cleft Lip
What is hypoplastic left heart syndrome?
It is a birth defect in which the left side of the heart is critically underdeveloped and affected individuals have profound cyanosis and cardiac failure
What are the three features of hypoplastic left heart syndrome on an anomaly scan?
A small ascending aorta
A thick-walled left ventricle
An enlarged right heart chamber
What is exomphalos?
It is an abdominal wall defect in which the baby’s intestines protrude inside the umbilical cord
What is exomphalos associated with?
Trisomy chromosome abnormalities
What is cleft lip?
An opening or split in the upper lip
What is the cause of a cleft lip?
It results when facial structures that are developing in an unborn babe don’t close completely
