Antenatal Care and Screening Flashcards
What are the objectives of antenatal care?
Detect and manage pre-existing maternal disorders that may affect pregnancy outcomes
Prevent or detect maternal and foetal complications
Detect congenital foetal problems if requested
What antenatal appointments are offered to low risk pregnancies?
Booking visit = 8-12 weeks Review at 16 weeks
Foetal anomaly scan = 20 weeks
Reviews at 25, 29, 31, 34 and 35 weeks
When are women seen by the midwife if they haven’t given birth after 36 weeks?
38, 40, 41 and 42 weeks
What is covered in the history and examination at the booking appointment?
History = obstetric, medical, surgical, medications, allergies, mental health, family, social Examination = height, weight, blood pressure
What bloods are done at the booking appointment?
Haemoglobin, Rhesus status and antibodies, syphilis, HIV, hep b and C, urinalysis
What is the purpose of the US done at the booking appointment?
Confirm viability and whether singleton/multiple
Confirm gestational age = most accurate time
Detect major structural abnormalities
Offer trisomy screening
What is Naegele’s rule used to predict?
Estimated due date = add nine months and seven days (280 days) to date of onset of last menstrual period, only used until US scan is performed
What is used to estimate gestational age in late bookers?
Head circumference
What are the objectives of the 20 week scan for foetal abnormalities?
Reduction in perinatal mortality and morbidity
Potential for in utero treatment
Identification of conditions amenable to neonatal surgery
Prepare women/families and offer reproductive choice
What areas are covered by the foetal antenatal screening programme (FASP)?
Head and neck, face, chest, abdomen, spine, limbs, uterine cavity
What abnormalities are looked for by the foetal antenatal screening programme (FASP)?
Edward’s and Patau’s syndromes
Open spina bifida and lethal skeletal dysplasia
Cleft lip, exomphalos and anencephaly
Diaphragmatic hernia and gastroschisis
Congenital heart disease and bilateral renal agenesis
How common are major structural abnormalities in pregnancy?
Occur in 2-3% = majority occur in low risk pregnancies
What is placenta praevia?
Placenta is low lying and covers all/part of cervix = identified at 20 week anomaly scan
What should be done in women with a low placenta on their 20 week scan?
Repeat another US scan at 32 weeks
Why may you need to do a transvaginal scan to assess placental position?
If foetus is in front of placenta = transabdominal scan can’t get adequate view
What trisomies can be screened for in the first trimester?
Trisomy 21 = Down’s syndrome
Trisomy 18 = Edward’s syndrome
Trisomy 13 = Patau’s syndrome
What are some features of Down’s syndrome?
Impossible to predict outcomes
50% have normal scans
Cardiac defects are common
What are some features of Edward’s syndrome?
Complete trisomy carries high risk of stillbirth
Partial trisomy is life limiting and associated with severe disability
What are some features of Patau’s syndrome?
Complete trisomy is usually lethal
Multiple abnormalities can be seen on scan
What additional tests are offered if there is a high chance for any trisomy?
NIPT = non-invasive prenatal testing
How is trisomy screened for in the first trimester?
Measure thickness of skin behind foetal neck (Nuchal thickness) = measured at 11-13+6 weeks with US, combined with HCG and PAPP-A
What value of Nuchal thickness would be considered normal?
Value <3.5mm considered normal if CRL is between 45-84mm
What should all women undergoing screen for Down’s syndrome have before bloods are taken?
A dating US scan
What is offered to if Nuchal thickness is unable to be measured?
Offer second trimester blood test = can only detect Down’s syndrome
What screening can be done for Down’s syndrome in the second trimester?
Blood sample at 15-20 weeks
Assay of HCG and AFP
What is the relationship between Down’s syndrome and maternal age?
Down’s syndrome is associated with older maternal age
What is NIPT also known as?
Cell free foetal DNA
What does NIPT do?
Detects foetal DNA fragments in blood sample from mother
When is free foetal DNA detectable in maternal blood?
From 10 weeks = amount rise as pregnancy advances
What are the benefits of NIPT?
More accurate than combined tests
More successful at detecting Down’s syndrome
Carries no risk of miscarriage
What diagnostic tests can be done for Down’s syndrome?
Amniocentesis = usually performed after 15 weeks, carries miscarriage rate of <1%
Chorionic villus sampling = usually performed after 12 weeks, carries miscarriage rate of <2%
What are two common heritable haematological disorders?
Sickle cell anaemia and thalassemias
What are some risks associated with sickle cell anaemia during pregnancy?
Anaemia, C-section, amnionitis, sickle chest syndrome, thrombophlebitis, premature birth, placenta praevia, bone crisis, perinatal mortality, miscarriage, stroke
When is maternal anaemia screened for?
At booking and 28 days = aim to optimise Hb before birth, may have deficiency of iron, folate or B12
When should all women have their blood groups and Rhesus status determined?
At booking and at 28 weeks
Why is it important to identify red cell antibodies?
Incase transfusion needed = need antibody matching
Some red cell antibodies cause foetal anaemia
So anti-D injection can be given to prevent D antigens forming in Rhesus negative women
When are anti-D injections given?
Routinely at 28 weeks and after sensitising event
After birth if baby is Rhesus positive
What are the risk factors for gestational diabetes?
BMI >30, previous macrosomic baby (>=4.5kg), previous gestational diabetes, family history of diabetes
What is offered to women with any risk factors for gestational diabetes?
2hr OGTT = diagnostic if fasting >=5.6 mmol/l or 2hr >=7.8 mmol/l
What is recommended at each appointment from 24 weeks onwards?
Serial measurement of symphysis fundal height (SFH)
When should women be referred for US measurement of foetal size?
Single SFH plot <10th centile
Serial measurement shows slowing/static growth
If measurement inaccurate (e.g BMI >35)
What prophylaxis is given to women at high risk of pre-eclampsia?
150mg aspirin daily from 12-36 weeks
What women are considered high risk of pre-eclampsia?
Hypertensive disease during previous pregnancy, CKD, autoimmune disease, diabetes, chronic hypertension
What is given as prophylaxis to women at moderate risk of pre-eclampsia?
75mg daily from 12 weeks until birth
What women are considered at moderate risk of pre-eclampsia?
First pregnancy, age >=40, pregnancy interval >10 years, BMI >=35, family history, multiple pregnancy
What conditions are screened for using urinalysis?
UTI, asymptomatic bacteriuria, pre-eclampsia, diabetes
Why are all women screened for domestic abuse and FGM?
Possible need for deinfibulation during pregnancy or labour to enable vaginal delivery
What conditions are screened for at the booking appointment?
Haemoglobulinopathies, hep B and C, HIV, syphilis, red cell antibodies, anaemia, multiple pregnancy, trisomy
What conditions are screened for at the 20 week foetal scan?
Cleft lip, congenital heart disease, limb defects, placenta praevia, diaphragmatic hernia, abdominal wall defects, lung/brain/urinary tract anomalies
What is screened for at the 28 week appointment?
Red cell antibodies, anaemia
