Week 4 Flashcards
When does blastocyst implant into uterus?
3-5 days: Transport of blastocyst into the uterus
5-8 days: blastocyst attaches to lining of uterus.
Function of trophoblastic cells
differentiate into multinucleate cells (syncytiotrophoblasts) which invade decidua and break down capillaries to form cavities filled with maternal blood
Contenst of placental villi
contains fetal capillaries separated from maternal blood by a thin layer of tissue – no direct contact between fetal & maternal blood
When is fetal heart and placenta functional?
5th week
How is corpus luteum stimulated?
Human chorionic gonadotropin (HCG) signals the corpus luteum to continue secreting progesterone
How does placenta act as fetal lungs?
Oxygen diffuses from the maternal into the fetal circulation system (PO2 maternal > PO2 fetal).
Carbon dioxide, (partial pressure is elevated in fetal blood) follows a reversed gradient.
3 factors facilitating O2 supply to foetus
- Fetal Hb
- Higher Hb concentration in fetal blood
3.Bohr effect
Describe HCG function
- prevents involution of Corpus Luteum
(CL: stimulates progesterone, estrogen)
*effect on the testes of male fetus - development of sex organs
Describe human placental lactogen function
produced from ~ week 5 of pregnancy
growth hormone-like effects
protein tissue formation.
decreases insulin sensitivity in mother
more glucose for the fetus
involved in breast development.
When do HCG levels start to fall?
12-14w
- this is when nausea, vomiting etc start to stop
Cardio changes in pregnancy
HR - incr to 90
- incr cardiac output need
BP - drops in 2nd trimester
- UP circulation expands
Why are pregnant women advised not to lie on back?
Uterus compresses vena cava
ECG changes in pregnancy
Relative sinus tachycardia
Slight left axis deviation
Inverted or flattened T-waves (Leads III, V1-V3)
Q-wave (Leads II, III, aVF)
Atrial and ventricular ectopic beats more common
Levels of Hb in anaemia in pregnancy
First trimester Hb <110g/L
2nd and 3rd trimester Hb <105g/L
Postnatal Hb <100 g/L
Postpartum haemorrhage is quantified by loss of how much blood?
> 500ml blood
Changes to maternal coagulation
Hypercoagulable state
Reduces risk of haemorrhage during and after delivery
Increased risk venous thromboembolism (Ddimer not used to test for PE)
Management of major haemorrhage in obstetrics
Tranexamic acid
Transfusion 4xRBC
THEN Consider FFP >2000ml or coagulopathy
Respiratory changes in pregnancy
Respiratory rate increases
Tidal and minute volume increases (50%)
pCO2 decreases slightly
Vital capacity and PO2 don’t change
Urinary system changes in pregnancy
GFR and renal plasma flow incr
Increased re-absorption of ions and water
Slight increase of urine formation
Postural changes affect renal function
Changes to metabolism/diet in pregnancy
200 extra kcal/day should be ingested by mother
85% fetal metabolism, 15% stored as maternal fat
Extra protein intake - 30g/day
End of pregnancy - fetal glucose need 5mg/kg/min
Fetus has really high metabolic demands
- accelerated starvation of mother
- reduced insulin sensitivity
Nutritional needs in pregnancy
Folic acid (folate) - reduces risk of neural tube defects
Vitamin D supplement
High protein diet, higher energy uptake
Iron supplements may be required
B vitamins - erythropoesis
- NO VITAMIN A
Hormonal changes at labour
Uterus becomes progressively more excitable
Estrogen:progesterone changes incr excitability
Prostaglandins inhibit contractility
Oxytocin incr contractions and excitability
Drugs used to induce labour
Prostaglandins to soften cervix
Oxytocin to induce contraction
Stages of labour
1st stage: cervical dilation
(8-24 hours)
2nd stage: passage of the fetus through birth canal
(few min to 120 mins, epidurl can make it a bit longer)
3rd stage: expulsion of placenta.
Hormonal changes affecting lactation
Estrogen - growth of ductile system
Prog - development of lob/alveolar
(these both inhibit milk production, sudden drop after birth)
Porlactin - stims milk prod, steady rise from week 5 to birth
Oxytocin - milk let down reflex
Why should you use POP as birth control is breastfeeding?
Progesterone is much less inhibiting of milk production than oestrogen
How to predict EDD?
Naegele’s Rule
Onset of LMP + 9 months + 7 days
Foetal meausurements to estimate due date
Crown rump length
AFTER 14 WEEKS
Head circumference
Main US scans in pregnancy
Initial after booking app
Anomaly scan at 20w
Define placenta praevia
the placenta is low lying in the uterusandcovers all or part of the cervix. Its site is identified at the anomaly scan
recheck at 32 weeks US (somtimes TVUS)
Trisomy risk assessment
Measure of skin thickness behind fetal neck using ultrasound (Nuchal thickness; NT)
+ HCG + PAPP-A
> 3.5mm is considered high risk
Second trimester T21 only:
Blood sample at 15-20 weeks
Assay of HCG and AFP
Low AFP + high HCG + high maternal age?
Higher chance of T21
What is NIPT?
Nn-invasive prenatal testing
Cell free fetal DNA (cffDNA) testing
- detectable from around 10 weeks of pregnancy
- screens for chance of DSS
Diagnostic tests in pregnancy
Amniocentesis:
Usually performed after 15 weeks
Carries a miscarriage rate of <1%
Chorionic villus sampling:
Usually performed after 12 weeks
Carries a miscarriage rate of <2%
IDing maternal anaemia
Iron deficiency
Folate deficicy
B12 deficiency
Screened at booking and 28 weeks
Aim to optimise Hb prior to birth
Why is anti-D given?
To prevent D antigens forming in Rh negative women
Given routinely at 28 w and after any sensitizing event
E.g.
(TOP, APH, invasive procedure, external cephalic version, fall, road traffic incident ect)
Given again after birth if baby Rh +ve
How is gestational diabetes tested for?
Use the 2‑hour 75g oral glucose tolerance test (OGTT) to test for gestational diabetes in women with risk factors
Diagnose gestational diabetes if the woman has either:
a fasting plasma glucose level of 5.6mmol/litre or aboveor
a 2‑hour plasma glucose level of 7.8mmol/litre or above.
How is foetal growth measured without USS?
Serial measurement of symphysis fundal height (SFH) is recommended at each antenatal appointment from 24 weeks of pregnancy as this improves prediction of a SGA neonate
- below 10th centile: ref to US
- high BMI, large fibroids: ref to US
Height changes in uterus fundus during pregnancy
12 weeks - just above pelvis
(16 weeks - in between)
20 weeks - umbilicus
(28 weeks - in between)
36 weeks - costal margin
Factors incr risk of preeclampsia
hypertensive disease during a previous pregnancy
chronic kidney disease
autoimmune disease such as systemic lupus erythematosis or antiphospholipid syndrome
type 1 or type 2 diabetes
chronic hypertension.
take 150mg aspirin daily from 12-36weeks
Trend of BP changes in pregnancy
Reduction in 1st trimester
Stays low
Then increases as nearing term
Often overshooting after birth
Highest at day 3/4 post-birth
Defs of hypertension in pregnancy
≥140/90 mmHg on 2 occasions , 4 hours apart
> 160/110 mmHg once
Mild >150, >100
Mod 150-200, 100-109
Severe .160, >110
Management of chronic HT in pregnancy
ACEi/ARBs/thiazide contraindicated (stop within 2 days)
Lifestyle mods
Sometimes won’t need meds due to physiological changes in pregnancy
Describe gestational hypertension
2nd half of pregnancy, resolves 6 weeks after delivery
No proteinuria or systemic features
Better outcomes than pre-eclampsia
Can progress to PT depending on gestation
Management of GH at birth and postnatally
Birth usually > 37 weeks unless poorly controlled hypertension
Daily BP monitoring
- <130/90 (140 if chronic)
Continue methyl dopa for 2 weeks then review (2 days if chronic)
Describe preeclampsia
Multi-system disorder
Diffuse vascular endothelial dysfunction widespread circulatory disturbance
May be asymptomatic
Family history increases risk
Triad of pre-eclampsia
Hypertension
Proteinuria (UPCR >30mg/mmol)
Oedema
Absence does not exclude diag
Classificaton of pre-eclampsia
Early <34 weeks
- uncommon, assoc with lesions of placenta, higher risk of complications than late
Late >34 weeks
- majority of cases, minimal placental lesions, most deaths occur in late disease, maternal factors very important
Pathogenesis of pre-eclampsia
Stage 1 - abnormal placental perfusion
- placental ischaemia
- trophoblasts don’t invade decidua, spiral arteries stay narrow and high pressure, less blood/nutrients to baby
Stage 2 - maternal syndrome
- an anti-angiogenic state associated with endothelial dysfunction
- leads to damage throughout body e.g. cardiac, renal, hepatic changes
Pres of liver disease in pregnancy
Epigastric/ RUQ pain
Abnormal liver enzymes
- ALT > 150 assoc with increased morbidity
Hepatic capsule rupture
e.g. Haemolysis, Elevated Liver Enzymes, Low Platelets
Pres of pre-eclampsia
Headache
Visual disturbance
Epigastric / RUQ pain
Nausea / vomiting
Rapidly progressive oedema
Signs of pre-eclampsia
Hypertension
Proteinuria
Oedema
Abdominal tenderness
Disorientation
Small for Gestational Age (SGA) Fetus
Intra uterine fetal death (might be first pres)
Hyper-reflexia / involuntary movements / clonus (can develop into eclampsic seizure)
Investigations for preeclampsia
Urea & Electrolytes
Serum Urate
Liver Function Tests
Full Blood Count
Coagulation Screen
Urine Protein Creatinine Ratio (UPCR)
Cardiotocography
Ultrasound - fetal assessment
Management preeclampsia
Early antenatal assessment - identify risk factors
Hypertension < 20 weeks - look for secondary cause
Antenatal screening - BP, urine, symptoms, Uterine Artery Doppler
Treat hypertension
Maternal & fetal surveillance
Timing of Birth
Medical prevention of those at risk of preeclampsia
75-150mg aspirin from 12 weeks (prevents thrombosis)
More than 1 mod risk
- 1st preg, >40, preg interval >10 years, BMI>35, FHx
High risk
- HT in prev preg, CKD, AI, diabetes/HT
Notch sign on uterine artery doppler
Notch is sign of high resistance in the vessel
- placenta not dev normally
- risk of preeclampsia and fetal growth restriction
When to offer antihypertensives in preeclampsia
Offer treatment to women not on treatment if
SBP>140 mmHG or DBP>90 mmHg
Target BP = 135/85 mmHg
UNLESS sys <110, symptomatic hypotension
Medical management of hypertension in pregnancy
Methyl dopa
Labetalol
Nifedipine
Hydralazine
Doxazocin
When to hospitalise in pre-eclampsia
SBP > 160 mmHg or higher
Abnormal blood tests (creatinine >90,
ALT >70, platelets <150)
signs of impending eclampsia
signs of impending pulmonary oedema
other signs of severe pre-eclampsia
suspected fetal compromise
Baby usually delivered within 2 weeks of diagnosis
Magnesium sulfate
Used to treat eclamptic seizures (4g IV over 5 mins, maintain with 1g/hour)
Also in run up to pre-term birth
Improves neuro outcomes for baby
Describe eclampsia
Tonic-clonic (grand mal) seizure occuring with features of pre-eclampsia
>1/3 will have seizure before onset of hypertension / proteinuria
More common in teenagers
Associated with ischaemia / vasospasm
Manage BP, prevent seizures, fluid balance, delivery
What is large for dates?
Symphyseal-fundal height >2cm for Gestational age
Causes of large for dtes
Wrong dating
- concealed, vulnerable, transfer of care from abroad
Multiple pregnancy
Polyhydraminos
Fetal macrosomia
Diagnosis of macrosomia
USS EFW >90th centile, AC>97TH Centile
Risks of fetal macrosomia
clinican & maternal anxiety
Labour dystocia
Shoulder dystocia- more with diabetes
Post-partum haemorrhage
Management of large for dates
Exclude diabetes
Reassure
Conservative vs IOL vs C/S delivery
Don’t induce labour just because you think baby is big
Diagnosis of polyhydraminos
Excess amniotic fluid
- Amniotic Fluid Index (AFI >25cm)
- Deepest Pool >8cm
- Subjective
Causes of polyhydraminos
MATERNAL:
Diabetes
Red cell antibodies
FETAL:
Anomaly- GI atresia, cardiac, tumours
Monochorionic twin pregnancy
Hydrops fetalis – Rh isoimmunisation
Viral infection
Symptoms of polyhdraminos
Abdominal discomfort
Pre-labour rupture of membranes
Pre-term labour
Cord prolapse
Signs of polyhydraminos
Large for dates
Mal-presentation
Tense Shiny Abdomen
Inability To feel fetal parts
Investigatiosn for polyhydraminos cause
Viral serology Toxoplasmosis, CMV, Parvovirus
Antibody Screen
USS- fetal survey- lips, stomach bubble
Management polyhydraminos
Patient information- complications including preterm rupture of membranes
Serial USS- growth, LV, presentation
IOL by 40 weeks
Risk: malpresent, cord prolapse, PPH
May resolve spontaneously
2 types zygosity in multiple pregnancy
Monozygotic : splitting of a single fertilised egg (30%)
Dizygotic: fertilisation of 2 ova by 2 spermatozoa(70%)
Types of chorionicity in multiple pregnancy
Essetially no of placentas per foetus
(1 Placenta vs 2 Placentas)
Dizygous – always DCDA (own placenta, own sac)
Monozygous- MCMA, MCDA, DCDA, conjoined; depends on time of splittingof fertilised ovum
Time of cleavage related to chorionicity
Day0-3: DCDA
Day 4-7: MCDA
Day 8-14: MCMA
Day 15: Conjoined twins
Lambda sign suggests
Multiple pregnancy (twin peaks)
Can see 11-13+6 weeks
Clin pres of multiple pregnancy
SYMPTOMS
Exaggerated pregnancy symptoms e.g. excessive sickness/ hyperemesis gravidarum
SIGNS
High AFP
Large for dates uterus
Mutiple fetal poles
USS confirmation at 12 weeks
Complications of multiple pregnancy
Higher perinatal mortality
Congenital anomalies (acardiac twin)
Pre term
Growth restriction
IUD
CP
Twin to twin transfusion
Maternal: HG, anaemia, PET, APH
AN management of twins
MC 2 weekly from 16/40
Anomaly USS 18-20 weeks
DC 4 weekly
Fe supp, low dose aspirin, folic acid
Define SGA
Small for gestational age
Abdominal circumference (AC) or estimated fetal weight (EFW) less than the 10th centile (population or customised charts available)
Severe SGA = AC or EFW <3rd centile
Define fetal growth restriction
Failure of the fetus to attain their growth potential
Difficult to identify in practice
All babies below 3rd centile
Below 10th centile with evidence of placental dysfunction
Define low birth weight
Any baby born with a weight less than 2.5kg at any gestation
Risks of FGR and SGA
Hypoxia
Stillbirth
Hypoglycaemia
Asphyxia
Hypothermia
Polycythaemia
Hyperbilirubinaemia
Abnormal neurodevelopment
Complications related to prematurity if preterm delivery
Maternal causes SGA
Lifestyle: smoking, alcohol and drugs
Very low or high BMI
Age
Maternal disease eg hypertension, renal disease
Placental causes SGA
Infarctions
Abruption (APH)
Association with hypertensive diseases
Fetal causes SGA
Infection e.g. rubella, CMV, toxoplasmosis
Congenital anomalies
Chromosomal abnormalities
Prevention of SGA
Aspirin if at risk PET
Vit D for all
Smoking cessation
Drugs service input
LMWH for APLS
How often are FGR high risk pregnancies offered scans?
Growth scans every 4 weeks from 28 weeks (sometimes 24 weeks)
Measurements needed for EFW
Abdo circumference + head circumference + femur length
Liquor volume in FGR
Poor sign in context of FGR would be reduction in DVP as marker of reduced renal perfusion and urine output
(normal >2cm and <10cm)
Pulsatility index parameters
Reduces as gestation advances
<1.4 always normal
MCA doppler function
Indicates brain perfusion
Redistribution of blood to vital organs such as brain
Reduced PI in a compromised fetus
Increased peak systolic velocity in fetal anaemia
Useful additional marker in SGA/FGR after 32 weeks
Ductus venosus doppler fucntioon
A direct reflection of fetal heart function
A-wave (atrial flow)
- Becomes progressively deeper as fetal condition worsens
Used to time delivery
Particularly useful in preterm FGR
Moderate predictive value of fetal acidaemia and adverse outcome
Management SGA between 3rd and 10th centile
Fortnightly scans for fetal growth, DVP and dopplers
Ensure regular BP + urine check
Advice on symptoms of pre-eclampsia, increased risk of stillbirth and to report reduced movements immediately
Offer IOL at 39 weeks
- aim to deliver by 39+6 weeks
Management SGA under 3rd centile
Once weekly dopplers plus liquor volume
Individual plan
Counsel on signs of preeclampsia, stillbirth, contact support
Delivery 37 weeks if no concerns
- no later than 37+6
Planning for preterm birth
Steroids up to 33+6 weeks
Magnesium sulphate for fetal neuroprotection up to 29+6 weeks
Delivery with immediate availabiity in NICU
CS if abnormal dopplers or v premature
IOL less likely
IP antibios with benzylpenicillin up to 36+6 for vaginal births, risk of strep A
When do pregnant people need more calories?
Last 12 weeks
200 extra per day
How much caffeine allowed in pregnancy?
200mg
- 2 mugs instant
- 1 mug filter
- 3 mugs tea
Supplements required in pregnancy
400ug folic acid pre-conception and during first trimester (13th week)
10ug vitamin D during pregnancy and continue to breastfeeding
When may someone need extra folic acid in pregnancy?
5mg high dose
Previous pregnancy affected by spina bifida
Woman/ partner has spina bifida
Anticonvulsants for epilepsy
Coeliac disease
Diabetes
BMI is 30 or more
Sickle-cell anaemia or thalassaemia (higher dose of folic acid will also help to prevent and treat anaemia)
Folic Acid Deficiency
Fetal risks of maternal vitamin D deficiency
SGA, Neonatal Hypocalcaemia, Asthma/Respiratory Infection, Rickets
How can you avoid listeriosis in pregnancy?
UHT pasteruised milk
No ripened soft cheese e.g. brie
No pate or deli meat
No undercooked food
Avoid animals giving birth
How to avoid salmonella in pregnancy?
Avoid raw/partially cooked eggs/fish/poultry
Avoiding toxoplasmosis in pregnancy
Good hand hygiene with food
Washing fruit/veg/salad
Cook meat well
Gloves while gardening
Avoid contact with cat faeces
Complications of iron deficiency in pregnancy
Tiredness
Shortness of breath
Preterm labour
Still birth
Intrauterine growth restriction / low birth weight
Placental Abruption
Post partum haemorrhage
Neonatal iron deficiency in their first 3 months of life
Neurodevelopmental delay in baby
How does NIPT determine chance of trisomy 21 in pregnancy?
Blood test to test the free fetal DNA in maternal serum
If there’s too much chromosome 21 in mother’s serum = high chance pregnancy
What drug is used first in TOP?
Potassium chloride
Rh-ve pregnant woman with anti-D antibodies has partner who is Rh+ve, what is the most appropriate next test?
NIPD
- to ID foetus Rh status
