Antenatal Care Flashcards
Definitions for SGA?
- SGA - Infant with birth weight <10th centile for gestational age. Severe SGA - <3rd centile for gestational age.
- Foetal SGA - estimated foetal weight (EFW), or abdominal circumference (AC) <10th centile. Severe foetal SGA- EFW or AC <3rd centile.
- Foetal growth restriction (FGR) - When a pathological process has restricted genetic growth potential, presenting with reduced liquor volume (LV) or abnormal doppler studies. (Likelihood of FGR higher in SGA foetus).
- Low birth weight - an infant with a birth weight <2.5kg.
Ax and PPx for SGA?
- Constitutionally small - 50-70% - small size at all stages but growth following centiles, no pathology, contributing factors - ethnicity, parental height, sex.
- Placental mediated growth restriction - growth normal initially but slows in utero (cause for FGR), due to placental insufficiency. Maternal factors predisposing to this include - pre-pregnancy low weight, substance abuse, autoimmune, renal, diabetes and chronic hypertension.
- Non-placental mediated growth restriction - Growth affected foetal factors such as chromosomal/structural anomalies, foetal infection, metabolic errors.
Minor risk factors of SGA?
At booking, and at 20 weeks gestation - all women should be assessed for risk factors of SGA.
1) Maternal age >35
2) Smoker <10
3) Previous pre-eclampsia
4) Nulliparity
5) Pregnancy interval <6m or >5yrs
6) Low BMI (<20)
7) IVF singleton
8) Low fruit intake
Major risk factors of SGA?
1) Maternal age >40
2) Smoking >10
3) Vigorous daily exercise
4) Cocaine use
5) Previous stillbirth
6) Previous SGA baby
7) Maternal/paternal SGA
8) Heavy beeding
9) Maternal disease (renal, APS, diabetes, chronic HT)
10) Low PAPP-A
Diagnosis of SGA?
- Ultrasound biometrics - EFW and AC plotted on centile charts based on maternal characteristics (height, weight, ethnicity and parity), gestational age and sex.
- Ratio of HC and AC significant - symmetrically small may suggest constitutionally small, whereas asymmetrically small foetus may suggest placental insufficiency.
- (Placental insufficiency results in impaired kidney function - oligohydramnios)
Other investigations - detailed anatomical survery, uterine artery doppler (UAD), karyotyping, screening for infections.
Management of SGA?
- Prevention - Modifiable risk factors should be managed to help prevent SGA - promoting smoking recession and optimising maternal disease, women with high risk pre-eclampsia aspirin 75mg daily from 12 weeks gestation until delivery.
- Surveillance - Uterine Artery Doppler (UAD) - every 14d if normal more frequent if not, Middle Cerebral Artery Doppler (MCAD), Ductus Venosus Doppler (DVD), amniotic fluid volume, symphysis fundal height.
- Delivery - If deliver being considered 24-35+6 weeks gestation a single course of ANTENATAL STEROIDS should be given.
Indications for delivery of an SGA baby?
<37 weeks - absent/reverese end-diastolic flow on doppler - C-section.
By 37 weeks - abnormal UAD or MCAD - can offer induction.
At 37 weeks - abnormal UAD or MCAD - can offer induction.
Continuous foetal heart rate monitoring required from onset of contraction - if induction for an SGA foetus.
Neonatal Complications of SGA?
1) Birth asphyxia
2) Meconium aspiration
3) Hypothermia
4) Hypo/hyperglycaemia
5) Polycythaemia
6) Retinopathy of prematurity
7) Persistent pulmonary hypertension
8) Pulmonary haemorrhage
9) Necrotising enterocolitis
Longterm complications of SGA?
1) Cerebral Palsy
2) Obestiy
3) Hypertension
4) T2DM
5) Behavioural problems
6) Depression
7) Alzheimer’s
8) Cancer
9) Precocious puberty
What is RBC isoimmunisation?
- Describes production of antibodies in response to an isoantigen present on an RBC.
- Maternal isoimmunisation occurs when mother’s immune system is sensitised to antigens on the foetal RBC - resulting in production of IgG.
- In subsequent pregnancies - these antibodies can cross the placenta and attack foetal red blood cells - leading to haemolysis and anaemia (haemolytic disease of the newborn).
PPx of RBC isoimmuisation?
- This occurs when foetal cells enter the maternal circulation via a sensitising event such as an antepartum haemorrhage or abdominal trauma, or during delivery.
- Rarely any problems in primary exposure - subsequent pregnancies - maternal antibodies cross the placenta and attack foetal RBCs (if they carry same antigen). Haemolysis and anemia can occur.
- Rhesus D isoimmunisation is only possible when RhD- women and RhD+ foetus blood come into contact - and maternal anti-D antibodies are produced.
- In later pregnancy - if child is also RhD+, anti-D antibodies cross placenta and bind to foetal RBC’s - causes autoimmune attack in foetus destroying it’s own RBC’s - anaemia (HAEMOLYTIC DISEASE OF NEWBORN).
Anti-D immunoglobulin?
If sensitising event occurs - maternal immunisation can be prevented - administration of Anti-D immunoglobulin - which binds to any RhD+ cells in maternal circulation (no immune response).
Indications for use of anti-D immunoglobulin:
In RhD NEGATIVE women - administration of anti-D IG should be considered following any sensitising event:
1) Invasive obstetric testing (amniocentesis or CVS)
2) PPH
3) Ectopic pregnancy
4) External cephalic version
5) Fall or abdominal trauma
6) IU death
7) Miscarriage
8) Termination of pregnancy
9) Delivery (normal, instrument or caesarian section)
Investigations and management of RBC isoimmunization?
TWO MAIN BLOOD TESTS CONSIDERED FOLLOWING SENSITISING EVENT:
1) Maternal blood group and antibody screen
2) Feto-maternal haemorrhage (FMH) test - KLEIHAUER TEST - assessing how much foetal blood has entered maternal circulation, and determines how much anti-D immunoglobulin should be administered.
AFTER DELIVERY - Rhesus status of baby should be checked - if baby is RhD+ and mother is RhD- , an FMH/Kleihauer test is done, at least 500IU of anti-D immunoglobulin administered (increased according to FMH).
Management of Sensitising events:
Less than 12 weeks gestation:
- Indications - Ectopic, molar, heavy bleed, termination
- Investigations - maternal blood group and antibody screen (confirm RhD- and that no anti-D already formed)
- Dose - 250IU anti-D within 72 hours
12-20weeks:
- Indications - All sensitising events
- Investigations - Maternal blood group and antibody screen
- Dose - 250IU anti-D within 72 hours
Greater than 20 weeks:
- Indications - All sensitising events
- Investigations - Maternal blood group and antibody screen (confirm RhD- and anti-D), FMH/Kleihauer (how much foetal blood in maternal, how much anti-D needed)
- Dose - 500IU within 72 hours of the event (dose increased according to FMH)
