Antenatal Care and Screening in Pregnancy Flashcards
What are the aims of antenatal care?
- pre existing maternal disorders
- manage maternal complications
- manage fetal complications
- detect congenital fetal problems if requested by parents
- prepare circumstances of birth to ensure maximum safety for the mother and baby
- Give advice regarding lifestyle
- Offer reproductive choice
What makes a good screening test?
- highly sensitive and specific
- high positive predictive value
- easily used in a large population
- safe, cheap, quick
How can we calculate specificity and sensitivity?
Sensitivity = True positive /(positive + false negative) Specificity = True negative/(negative + false positive)
At what stages during a woman’s pregnancy does she normally have a scan?
11-13 weeks (as close to 12 as possible)
= Booking Scan
20 weeks
= Anomaly Scan
may have further scans closer to 40 wks if high risk
What parts of the history are involved in the booking appointment consultation?
- Menstrual and Obstetric Hx
- PMHx - risk of VTE?
- FHx - any inherited conditions?
- SHx
- DHx - do these need stopped in pregnancy?
- Surgical Hx (important if pt may require emergency C-section at end of pregnancy)
- Choose GREEN (midwife) or RED (obstetric input) pathway
What components of surgical history are important for the surgeon to know?
- any previous spinal surgery? (may contraindicate anaesthesia)
- Any previous ops? What anaesthesia was used? Was it straightforward?
- previous gynae operations that have caused complications?
What is used to prevent VTE in pregnancy if patients are high risk?
Fragmin
What is measured on a booking appointment to calculate an accurate due date?
Crown-Rump Length
more accurate than gestational calculator - 280 days from 1st day of last period
What investigations are carried out at an antenatal booking appt?
- Haemoglobin
- Blood group + Rhesus
- STIs - Syphilis, HIV, Hep B/C
- Urinalysis
- US
- Aneuploidy screening (Trisomies - Down’s Syndrome (21), Edwards Syndrome (18), Patau’s Syndrome (13))
What is the function of the booking appointment US scan?
- confirm viability of pregnancy OR ectopic/molar
- multiple pregnancy? (twins sharing placenta = highest risk!)
- Estimate gestational age
- Detect major structural anomalies
Screening for Down’s syndrome is offered to ALL pregnant mothers. TRUE/FALSE?
TRUE
- offered to all BUT they can decline
- mothers choice
What is involved in the antenatal follow up appointments carried out by the midwife?
Hx
- Physical and mental health
- Foetal movements
Examination
- BP and urinalysis
- fundal height
- Foetal Lie and presentation
- presenting part
- Foetal heart auscultation
What do clinicians aim to pick up on the 20 week foetal anomaly scan?
- Neural Tube defects (spina bifida, anencephaly)
- Cleft lip/palate
- heart defects
- abdominal wall defects (gastrochisis)
- placenta previa (placenta lying too low in womb and obscuring cervix)
Why is it important to identify Cleft lip/palate BEFORE a baby is born?
- relatively common 1 in 100
- prepare parents for baby needing surgery
- Speech and Language involved
- NG tube feeding potentially needed at birth
- may be associated with other genetic syndromes => check if foetus also has these
How can pregnant mothers essentially “grow out” of placnta previa?
- womb grows upwards
- placenta moves with it so that it is in a normal position before birth
=> No problems during labour
How is placenta previa investigated during pregnancy?
- If US scan (between 18 and 21 weeks) showed placenta extends over the cervix
- offer another abdominal scan at 32weeks
- If this second scan is unclear, offer a vaginal scan.
Why may parents choose to terminate a Down’s Syndrome pregnancy?
Many babies are born with severe disability and require lifelong treatment and care
=> Lot of work for parents
What percentage of foetus’ diagnosed with Down’s syndrome are terminated during pregnancy?
70%
What tests are used to detect Down’s Syndrome in the first trimester?
Bloods
PAPP-A (Decreased)
HCG (Increased)
Nuchal Translucency
What DIAGNOSTIC testing can be used for Down’s Syndrome?
Amniocentesis
Which of the antenatal tests carries the highest risk of Down’s syndrome if HIGH?
Nuchal translucency (more fluid behind neck = more likely to have DS)
Down’s Syndrome increases with increasing maternal age. TRUE/FALSE?
TRUE
Blood tests for Down’s syndrome can be taken in the second trimester. TRUE/FALSE?
TRUE
Blood sample at 15-20 weeks
Assay of HCG and AFP
BUT they are less accurate
What is involved in new Non-Invasive Prenatal Testing (NIPT)?
Cell free fetal DNA (cffDNA) testing
- can identify pregnant women at higher risk of baby with genetic conditions
- Blood sample from mother
- detects DNA from the mother but some fragments are from unborn baby
=> cell free fetal DNA (cffDNA) (detectable from 7 wks and rises as the pregnancy continues)
How will Non-Invasive Prenatal Testing (NIPT) become involved in the NHS antenatal guidelines?
- offered if high risk after first trimester screening
- less amniocentesis carried out as result (=> less miscarriages)
Describe the difference between amniocentesis and chorionic villus sampling as diagnostic tests
AMNIOCENTESIS (after 15 wks)
- no anaesthetic used (due to thin needle)
- US guided
- Miscarriage rate 1%
CHORIONIC VILLUS SAMPLING (after 12 weeks)
- Local anaesthetic used (as having to remove placental cells)
- US guided
- Miscarriage rate 2%
What major haemoglobin disorders are usually screened for with the first FBC at the booking appointment?
Sickle cell anaemia
Thalassemia
(both are Autosomal Recessive disorders causing abnormally shaped RBCs which carry inadequate Hb)
What can cause maternal anaemia and should be screened for antenatally?
Iron deficiency
Folate deficicy
B12 deficiency
Mothers are initially tested for anaemia at their booking scan. When is this followed up?
28 week appointment where bloods are repeated
Why is it important to regularise a mother’s haemoglobin before birth?
Low Hb = HIGH risk of post-partum haemorrhage and maternal death
What other tasks are carried out at the 28 week appointment?
If rhesus neg. give anti D prophylaxis
How can foetal anaemia be picked up on investigation?
Picked up on US scan
- peak Middle cerebral artery (MCA) flow indicates baby does not have enough Hb, and it is mostly being used to perfuse brain
How can mental health be screened throughout a woman’s pregnancy?
- Do you have new feelings and thoughts making 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 can’t cope? Are these feelings persistent?
- Do you feel you are getting worse?
What risk factors increase the likelihood of developing gestational diabetes?
- BMI >30
- previous macrosomic baby
- previous gestational diabetes
- FHx diabetes
- minority ethnic family origin with a high prevalence of diabetes
If a mother is deemed as high risk at her 20 scan, how many extra scans are normally offered and when?
24 wks
32 wks
36 wks
40 wks
Why is it important to take serial measurements of fundal height at each antenatal appt after 24 weeks?
- improves prediction of a Small for Gestational Age neonate
Women with moderate or high risk of pre-eclampsia are advised to start taking what medication from 12 weeks pregnancy until birth?
Low dose aspirin 75mg
this does NOT increase PP haemorrhage risk
Give examples of moderate Pre-eclampsia risk factors
- first pregnancy
- > 40years
- pregnancy interval >10years
- BMI >35
- FHx of pre-eclampsia
- multiple pregnancy.
What would be considered a high risk factor for the development of pre-eclampsia?
- previous pre-eclampsia
- chronic kidney disease
- autoimmune disease (e.g lupus/ antiphospholipid)
- Type 1/ 2 diabetes
- chronic hypertension.
What are we hoping to pick up on urinalysis in antenatal care?
UTI
Asymptomatic bacteriuria (assoc. with preterm labour)
PET
Diabetes
