Antenatal Flashcards
What effect does progesterone have in pregnancy?
Relaxes smooth muscle:
uterus
gut- constipation + acid reflux
ureters- hydronephrosis
Raises temperature
What effect does oestrogen has in pregnancy?
Breast and nipple growth
Water retention
Protein synthesis
Why does vaginal discharge increase in pregnancy?
Cervical ectopy
Cell desquamation
Vasocongested vagina > increased mucus production
How much does plasma volume increase to in pregnancy?
3.8 Litres
What increases on the FBC are expected in pregnancy?
WCC (10.5)- neutrophilia from invading placenta ESR (x4) Cholesterol b-globulin Fibrinogen
What decreases are expected on the FBC in pregnancy?
Platelets- haemodilution + consumption
Urea
Creatinine
(small degree of hydronephrosis)
What happens to the inferior vena cava when pregnant woman lie supine?
From 20 weeks the gravid uterus compresses the ivc reducing venous return
How can ivc compression in pregnant women be reduced?
Lying in the left lateral position or wedging her tilted 15 degrees onto the left (restores venous return and thus cardiac output).
What effect does progesterone have on the lungs?
Relaxes smooth muscle of the diaphragm causing tidal volume to increase to 700mL
Why do pregnant women get breathless?
Maternal PaCO2 is set lower to allow the placenta to offload CO2 so breath more.
How soon will a pregnancy test give a positive result?
9 days after ovulation (day 23 of cycle)
How long into pregnancy is a pregnancy test positive?
20 weeks
How long does the corpus luteum produce progesterone for?
35 days
What three factors contribute to high risk pregnancies?
- Maternal age above 35
- Previous abnormal baby
- Family history of genetic condition
What does the ultrasound scan at 11-13weeks (+6 days) look for?
Nuchal translucency
Chorionicity- twins
When is the second abnormality scan?
18 weeks
What kinds of things is the ultrasound screen better or worse at identifying?
Good for:
Structural abnormalities that alter external anatomy
- anencephaly, spina bifida
Bad for:
internal structural abnormality- under 50% pick up
- heart disease, diaphragmatic hernia
What is choroid plexus cyst a soft sign for?
Trisomy 21- Down’s
Trisomy 18- Edwards
(choroid plexus is blood supply to brain)
What is echogenic bowel a soft sign for?
Trisomy 21
Cystic fibrosis- associated wit reduced bowel motility
Where is a-fetoprotein synthesised in the fetus?
the GI tract and liver
What pathologies can a high a-fetoprotein indicate?
Increased opening to amniotic sac:
Open neural tube defect
Examphalos
Tube Obstruction:
Kidney (post urethral valves) or gut abnormalities
Turner’s syndrome (XO)
(NB: not Downs which has low AFP)
What is a normal cause of high a-fetoprotein?
Twins
What can cause a low a-fetoprotein?
Chromosomal abnormalities- Down’s syndrome
Diabetic mother
When can amniocentesis be performed?
16 weeks
before then it has a 5% loss rate and may lead to talipes (club foot) or respiratory problems.
What is the advantage of amniocentesis over chorionic villus biopsy?
Amniocentesis provides a more accurate a-fetoprotein level to detect neural tube defects.
Chorionic villus biopsy can’t detect neural tube defects
What is the disadvantage of amniocentesis?
Problems detected late in pregnancy
-done at 16 weeks, cell culture for enzyme and gene probing takes 3 weeks
What is the chorionic villus biopsy loss rate?
4%
When can chorionic villus biopsies be taken up until?
20 weeks
after that use cordcentesis
What type of pregnancy is chorionic villus biopsy not recommended in?
Dichorionic multiple pregnancy
+ After 20 weeks
When is fetoscopy carried out and why?
At 18 weeks to find external abnormalities
Loss rates of all the invasive procedures for fetal abnormality?
Amniocentesis before 16 weeks- 5%
Amniocentesis after 16 weeks- 1%
Chorionic villus biopsy- 4%
Fetoscopy- 4%
What can nuchal translucency be a sign of?
Anomaly of heart and great arteries- leads to oedema in neck
Downs- more hydrophilic collagen in dermis
Turners- lymph obstruction
Nuchal translucency has a positive predictive value of 4%, what does this mean?
Out of 100 women with a positive result, 4 will have a chromosomal abnormality
What type of twins have a higher rate of false positives with nuchal translucency?
Monochorionic twins
What risk of Down’s prompts the option of invasive sampling in 1st and 2nd trimester?
1st: 1 in 150
2nd: 1 in 250
What does the combined test for Down’s entail?
nuchal translucency (high)
b-HCG (high)
pregnancy associated plasma protein (low)
woman’s age
How is risk assessed with the combined test for dichorionic fetuses?
Risk is done per fetus so use nuchal translucency of each for their own scores
What does the integrated test for Down’s entail?
Nuchal translucency
Pregnancy associated plasma protein (PrAP-A)
\+ Quadruple test (EFGHI): unconjugated Estriol maternal a-Fetoprotein free b-HCG Inhibin-A
What is the advantage and disadvantage of the integrated Down’s test over the combined test?
Advantage- better than combined test
Disadvantage- can only do the quadruple test with values from the 2nd trimester
What Down’s tests can be used in 2nd trimester?
The quadruple test:
Low:
AFP
unconjugated estriol
High: b-HCG
inhibin A
When can the quadruple test be used?
Between 15 weeks (+0 days) and 20 weeks (+0 days)
When can the combined test be used?
Between 10 weeks (+3 days) and 13 weeks (+6 days)
What are the indications for preimplantation genetic diagnosis?
Women who have repeatedly terminated pregnancy due to abnormality
Concurrent infertility
Recurrent miscarriage
+ if objections to terminations
In preimplantation genetic diagnosis how are different conditions detected?
Fluorescence in situ hybridisation- chromosomes
PCR- mongenic gene diseases
Women with 3 risk factors for thromboembolism should receive what Rx?
LMW heparin (like enoxaparin) fro 28 weeks + labour and 6 weeks after. With TED stockings given.
Lady with BMI above 40 gives birth.
What does she need after birth?
7 days of LMWH
After caesarian sections that occur whilst in labour what thromboprophylaxis should woman get?
7 days of LMWH
elective C-section is just a risk factor, of which 2 are needed to warrant post-birth LWH
What are the risk factors for thromboembolism in pregnancy?
Over 35
BMI >30 in early pregnancy
Parity >= 3
Multiple pregnancy
COAGULATION
Assisted reproduction
Ovarian hyperstimulation
Hyperemesis
Vomiting
PMH: Thromboembolism Thrombophilia Myeloproliferative disorder Sickle cell
ENDOTHELIAL INJURY Major infection- pyelonephritis, wound infection Smoker SLE Inflammatory bowel disease
Pre-eclampsia Nephrotic syndrome (hypertension, oedema, proteinuria)
FLOW Paraplegia Immobility for more than 2 days pubic symphysis dysfunction Long travel time (>3 hours)
Gross varicose veins
Flow: Labour for more than 24 hours Coag: Blood loss> 1L Transfusion >1L Endo injury: Mid-cavity forceps Elective caesarian Postpartum sterilisation
How does the LMWH regimen change if a woman has two risk factors rather than 3 in pregnancy?
3- Start LMWH straight away
2- Start LMWH after delivery
What factors should delay starting LMWH after birth?
Postpartum haemorrhage
Wait 4 hours after epidural catheter siting or removal
Wait 6 hours after traumatic epidural catheter placement
How is enoxaparin (LMWH) dosed according to weight?
For every 40kg give 20mg more SC OD, starting below 50kg.
What constitutes very high risk of VTE in pregnancy?
How should they be managed?
Recurrent VTEs
- antiphospholipid syndrome
- antithrombin deficiency
Or on long-term Warfarin
High dose of prophylaxis, giving dose BD instead of OD
or 75% of therapeutic dose (= 1mg/kg/12hrs)
What dose of LMWH do you give a pregnant woman who gets a VTE?
1mg/kg SC BD enoxaparin
What do you give a woman who gets a VTE post partum?
1.5mg/kg OD SC ENOXAPARIN
How should thromboprophylaxis regimen change as a very high risk woman for VTE onsets labour?
Go from giving it BD to OD the day before and the day of induction
A pregnant woman had a VTE in the past due to varicose veins that have since been removed. She has no other risk factors. What thromboprophylaxis should she receive?
LMWH for 6 weeks post birth
any previous VTE
What complications of sickle cell anaemia are commoner in pregnancy?
Painful crises
Prematurity
Fetal growth restriction
What factors in pregnancy could precipitate painful sickle cell crises?
Cold Hypoxia Dehydration- vomiting Over exertion Stress
Pregnant woman has chest pain and a cough
PMH: sickle cell
IHx: infiltrates on CXR
Acute Chest Syndrome
Respiratory symptoms + CXR infiltrates
How should acute chest crises in sickle cell patients be treated?
Blood transfusion
+ pneumonia antibiotics
ie Cephalosporin (cefotaxime) \+ Macrolide (Azithromycin)
What assessments do sickle cell pregnant women require?
Echocardiography- look for pulmonary hypertension
BP + urinalysis- higher risk of pre-eclampsia
U+E, LFTs- crises can damage liver or kidney function
Retinal screening- Proliferative retinopathy common
Iron levels- may need chelation due to transfusions
What prophylaxis and vaccines do hyposplenic patients need?
Daily Penicillin + Erythromycin
Vaccines: Hepatitis B Haemophilus influenza B Meningococcal H1N1 seasonal influenza Pneumococcal- every 5 years
What drug alterations should be made for sickle cell patients trying to conceive?
Stop ACEi and Angiotensin Receptor blockers
Start 5mg folic acid preconception
When can sickle cell prenatal testing be done?
8-10 weeks
For what Hb changes would transfusions be considered for sickle cell pregnant women?
If Hb falls to 6
or if Hb falls by 2g/dL from booking
What sickle cell complications in pregnancy would need an exchange transfusion?
Acute chest syndrome
Stroke
What pain relief should be used or avoided for sickle cell pregnant women with crises?
Use morphine/diamorphine
Avoid pethidine- increases risk of fits
What heparin regime should be given to sickle cell women after birth?
Heparin for 7 days if vaginal delivery
or for 6 weeks if caesarian
What is the maternal mortality associated with Eisenmenger’s syndrome and pulmonary hypertension?
30-50% so advise against pregnancy
Eisenmenger’s = right to left shunt
What thromboprophylaxis regime can be used for women with prosthetic heart valves?
Heparin IV on weeks 6-12 and 37 to term +7 days
Warfarin at other times
Why can’t Warfarin be used throughout pregnancy for women with prosthetic heart valves?
Fetal harm
What position should be avoided in labour for women with impaired cardiac function?
Avoid lithotomy position- causes dangerous rise in venous return after labour
Semi-sitting is best with short 2nd stage labour- instrumental delivery may be needed
In labour what drug should be avoided in mothers with cardiac impairment?
Ergometrine for expulsion of the placenta
use OXYTOCIN if necessary instead
Under what circumstances would a caesarian be given for a woman with cardiac impairment?
Only if she develops eclampsia should it be given. shouldn’t be done if she is in heart failure unless eclampsia occurs.
Rx for pregnant women who develop acute heart failure?
Furosemide 40mg IV slowly
Oxygen
Morphine 10mg IV
Ventilation if no improvement
Rx for pregnant woman with palpitations
ECG shows narrow complex tachycardia
Valsalva manoeuvre
Carotid massage
anaesthetise and cardiovert if unstable
IV adenosine if stable
What heart sounds can be normal in pregnancy?
Loud S1
an S3 heart sound
Ejection systolic murmur
What cardiac signs can be normal in pregnancy?
Pulsating neck veins (not raised JVP)
Oedema
Forceful apex beat
What CXR findings can be normal in pregnancy?
Slight cardiomegaly
Distention of pulmonary veins (due to increased plasma volume)
What signs are not normal in pregnancy?
A raised JVP in neck
Apex beat more than 2cm lateral to the midclavicular line
When is it best to hold off antidepressants until in pregnancy?
2nd trimester
Which antidepressants are typically prescribed in pregnancy?
Tricylics- AMITRIPTYLINE
blocks seratonin reuptake
What is the disadvantage of tricyclics in pregnancy?
Consequences of overdose are worse than SSRIs
What withdrawal symptoms of amitriptyline (TCA) are seen in neonates?
Agitation ± respiratory depression
(it’s an SNRI and 5-HT is involved in chemoreception at central respiratory centres, increases breathing rate so as conc lowers, so does breathing rate)
What withdrawal symptoms of imipramine (TCA) are seen in neonates?
(Imipramine also blocks serotonin uptake)
Colic
Spasms
Hypotension/hypertension (binds a-adrenergic Rs)
What withdrawal symptoms do neonates get from clomipramine (TCA) antidepressants?
Convulsions
What is the danger of using SSRIs in pregnancy for depression?
Persistent pulmonary hypertension of the newborn if used after 20 weeks gestation
Which SSRI in pregnancy is associated with least known risk?
Fluoxetine
Why is paroxetine SSRI contraindicated in pregnancy?
1st trimester- associated with cardiac malformations
withdrawal in neonate- convulsions
Which antidepressants have the lowest rate of transfer in breastfeeding?
Imipramine (TCA)
Nortriptyline (TCA)
Sertraline (SSRI)
Which antidepressants have the highest rate of transfer in breastfeeding?
Citalopram (SSRI)
Fluoxetine (SSRI)
What defects in the fetus is lithium therapy associated with?
Teratogenicity: Heart defects
ie Ebsteins abnormality
(displaced tricuspid valve allows back flow of blood into the R atrium)
For pregnant women who choose to stay on lithium therapy what investigation should be offered?
Fetal echocardiography at 16 weeks incase of heart defects
How should drug levels be monitored in women electing to stay on lithium during pregnancy?
Up to 36 weeks:
Measure 12hours after dose 4x a week
After 36 weeks:
Measure weekly
What lithium drug level is aimed for if continuing it in pregnancy?
As low as possible- under 0.4mmol/L
Can women taking lithium breastfeed?
No.
Can women with schizophrenia continue taking phenothiazines in pregnancy?
Yes = Dopamine 2 Receptor antagonist
What can phenothiazine use in pregnancy (for schizophrenia) cause in the newborn?
Phenothiazine = DA 2 R antagonist, causes parkinsonism symptoms in baby:
Hyperreflexia
Hypertonia
Tremor
Which antipsychotics can lead to raised prolactin levels and thus infertility?
Atypicals: Amisulpride
Sulpride
Risperidone
dopamine antagonists stop inhibition of prolactin
What can Olanzapine (anti-schizophrenic) cause in pregnancy?
Gestational diabetes due to weight gain. Atypicals are known to sometimes trigger metabolic syndrome
What side effects can anxiety medication cause in pregnancy?
Benzodiazepines- fetal malformation
Diazepam- floppy baby syndrome when withdrawal
b-blockers- retard fetal growth
What are the diagnostic indications for amniocentesis?
Prenatal genetic studies
Assess fetal lung maturity- if possibility of prematurity
Chorioamnionitis or TORCH infection (toxo, rubella, CMV, HSV, HIV)
Blood type, haemoglobinopathies
Neural tube defects
What is twin to twin transfusion syndrome?
Occurs with monochorionic pregnancies where placental vascular anastomoses cause disproportionate blood supplies.
One twin becomes anaemic- used too much oxygen
the other twin becomes plethoric and then jaundiced when red cells are destroyed at birth- used to too little oxygen
What structures need to be avoided during amniocentesis?
The umbilical cord and its insertion site.
Maternal bowel and bladder
What symptoms after amniocentesis are normal and which should be reported?
Expect: Mild cramping
Report: Vaginal bleeding/discharge, severe uterine cramping or fever
Avoid: coitus and anaerobic exercise for a day
Why might a genetic abnormality be detected in chorionic villus sampling but not in amniocentesis or fetal blood sampling?
Confined placental mosaicism- only the placenta contains the abnormality.
At inner cell mass stage, a few cells will derive the fetus and a few the placenta.
Could be only the placental precursors don’t correctly split the chromosomes (post-zygotic nondisjunction) or there’s trisomic rescue in the fetal cells (deletes extra chromosome)
What is antepartum haemorrhage defined as?
Bleeding from the genital tract after 24 weeks of pregnancy
What can cause antepartum haemorrhage?
Placental abruption- placenta separates from uterus lining
Placental praevia- placenta anchored in the lower uterine segment
Vasa praevia- fetal blood vesse;s running across uterine os
Genital tract source
What ares the dangers of anaemia in pregnancy?
Worsens postpartum haemorrhage
Predisposes to infection
Antagonises heart failure
Causes problems with postnatal malaria
Risk factors for placenta praevia
Age >40 Babies before (multiparity) Caesarian/ Previous uterine surgery Dilatation & cutterage (biopsies) Endometriosis + deficient Endometrial-manual removal of the placenta Fibroids Going smoking
What investigation best diagnoses a low lying placenta
Transvaginal ultrasound, not transabdominal
What investigation can be combined with ultrasound to diagnose vase praevia or placenta acreta?
3D Doppler USS /MRI
What is the most severe form of placenta praevia?
Major/Grade 4
Covers the internal os
How is major placenta praevia treated?
Caesarian section for delivery.
What are the different grades of placenta praevia?
- minor- placenta in lower segment, doesn’t extend to cervix
- minor- placenta extends to cervix, does not cover it
- major- placenta partially covers cervix
- major- placenta wholly covers cervix
What factors in placenta praevia would suggest caesarian is needed rather than vaginal delivery?
If placenta encroaches within 2cm of internal os
especially if it encroaches posteriorally or is thick
Why does placenta praevia predispose to postpartum haemorrhage?
Poor contractility of the uterus in the lower segment, where the placenta is lying.
If accreta suspected in a case of placenta praevia, when should the baby be delivered?
36-37 weeks with steroid cover and cross-matched blood available
Placenta weighs more than 25% of the baby and baby has proteinuria at birth and is swollen, what does this suggest?
Congenital nephrotic syndrome (HOP)
Common in Finnish population
Give 2 reasons why vasa praevia may occur?
- Velamentous cord insertion- cord inserts into chorioamniotic membranes instead of placenta, vessels are running with the cord
- Vessels may be joining an accessory lobe of the placenta to the main placental disk.
What are the issues of an anterior low-lying placenta?
During the caesarian the placenta may need to be parted to access the baby.
Also more possibility of accreta
What abdominal findings can be found with placenta praevia?
Soft uterus
High presenting part
25 year old, para 2 presents at 37 weeks
Pain at uterine fundus, fresh vaginal bleeding
Abdomen is hard and tender. Diagnosis?
- degenerating uterine fibroid
- pancreatitis
- placenta praevia
- torted ovarian cyst
- placental abruption
Placental abruption
Fundus where placenta normally is
What should be avoided with placenta praevia?
- Pervaginal examinations
2. PV intercourse
Why isn’t blood loss a good indicator of placental abruption severity?
Blood can collect behind membranes.
20 year old woman at 38 weeks gestation
Vaginal bleeding that started as membranes ruptured 20 minutes ago
CTG shows fetal bradycardia
Diagnosis?
Vasa praevia- stretching of os ruptures vessels
25 year old primip at 30 weeks
Fresh vaginal bleeding and abdominal pain
EHx: uterus is tender and irritable
Diagnosis?
Placental abruption
41 year old para 2 (caesarian sections) at 32 weeks
Heavy vaginal bleeding
Soft non tender uterus
Diagnosis?
Placenta praevia
RFs: age, babies before, caesarians
EHx typical
37 year old refugee, HIV positive
2/12 vaginal bleeding with intercourse
Diagnosis?
Cervical carcinoma
HIV increases risk
Definition of haemocrit?
Blood cells/Blood volume
22 year old primiparous woman
Vaginal spotting at 24 weeks gestation
Vulval itching and vaginal discharge
Diagnosis?
Vulvo-vaginitis (likely candida)
MCHC, mean corpuscular haemoglobin concentration
Hb concentration in a given volume of packed red cells
How does LMW heparin work?
Increases adhesion of anti-thrombin to factor Xa (10a)
What factors are involved in the intrinsic pathway of coagulation?
Factor 12, 11, 9, 8
Contact activation with damaged surface
What part of the clotting cascade does APTT measure?
The intrinsic, contact-activated pathway
Involves factors 12, 11, 9, 8
How does unfractionated heparin work differently to LMW heparin?
LMWH activates Antithrombin - inhibits factor Xa
UF heparin activates Antithrombin- inhibits factor Xa + thrombin
X > Xa
Prothrombin > Thrombin
Which proteins degrade Factor V and where is Factor V involved in the coagulation pathway?
Factor Va combines with Factor X to activate Thrombin
Protein S + Protein C degrade Factor V
Protein C resistance = factor V not degraded
Why is the Kleinhauer test used?
To determine how much fetal Hb is in the maternal blood stream and therefore whether fetal haemorrhage is the cause of fetal death
How does the Kleinhauer test work?
Acid is added to maternal blood which destroys adult Hb, leaving only the fetal Hb behind to be quantified.
Why might TSH be low in the first 20 weeks of pregnancy?
HCG suppresses it
What are the factors of hyperemesis gravidarum?
Persistent vomiting leading to:
5% of weight loss from pre-pregnancy weight
Ketosis
What are the risk factors for hyperemesis gravidarum?
Youth
Primips
Multiple
Molar pregnancy
PMH: diabetes,
hyperthyroidism,
psych illness,
eating disorder
FHx
SHx: non smokers, working women
What is thought to underlie morning sickness?
Steeply rising oestrogens
Excessively high levels of what are thought to cause hyperemesis gravidarum?
HCG
as molar and multiple pregnancy are RFs
If a woman has hyperemesis in one pregnancy, what is the likelihood of reoccurance?
15%
10% if she changes partner
How should hyperemesis gravidarum be investigated?
Urine dipstick- look for ketones
For guiding fluids: U+Es + Packed Cell Volume (FBC)
LFTs will be abnormal
TFTs- abnormality corresponds to severity of hyperemesis, indicates likely duration of hospital stay
Fluid chart, weights, BP lying and standing
USS- exclude twins or hydratidiform mole
How should Hyperemesis Gravidarum be managed?
Enoxaparin 40mg SC
Thiamine 40mg TDS (prevent Wernicke’s encephalopathy)
IV Saline + Potassium
Cyclizine 50mg TDS PO/IM for emesis
What things can help with hyperemesis?
Rest Ginger Pyridoxine- found in bananas, whole grains, avocados Dry bland food Carbonated drinks
What antiemetics are D2 antagonists
METOCLOPROMIDE
PROCHLOPERAZINE
CHLORPROMAZINE
DOMPERIDONE
Which antiemetic for pregnancy antagonises 5-HT 3 receptors?
ONDANSETRON
the only one with an S for Seratonin
Which antiemetic for pregnancy acts on antihistamine Rs?
Cyclizine
What are the potential side effects of phenothiazines like prochlorperazine or chlorpromazine (used for anti-emesis)?
Drowsiness
Extrapyramidal side effects- dystonia, parkinsonism
Oculogyric crisis- involuntary upwards looking
If someone has hyperemesis resistant to anti-emetics, what can be tried?
100mg BD Hydrocortisone
then 40mg Prednisolone OD
tapering down towards 20 weeks gestations
What do women taking steroids in pregnancy need to be monitored for?
UTIs
Gestational diabetes
What is anaemia in pregnancy defined as?
Hb below 11g/dL
How to treat iron deficiency anaemia in pregnancy?
Ferrous Sulphate 200mg OD
What can you give to anaemia patients not tolerating iron supplements?
What does it risk?
Parental (IV) iron
Anaphylaxis
After iron supplementation how long does it take for Hb levels to improve?
6 weeks
When should iron not be given for a microcytic anaemia?
When thalassaemia is suspected, iron levels will already be high.
Which thalassaemia is more severe for the fetus to have?
a thalassaemia is worse (as HbF is a2 y2)
b thalassaemia affects adult Hb (a2, b2)
How can thalassaemias be identified?
Chorionic villus sampling
What reduces risk of HIV transmission in pregnancy and peripuerium?
3 things
- Antiretroviral use
- Elective caesarian
- Bottle feeding
What should pregnant women found to be HIV +ve be tested for?
Antibodies against: Hep B + Hep C Varicella zoster measles toxoplasmosis
Genital tract infections