haematology in pregnancy Flashcards
What is the inheritance for sickle cell
What is the gene mutation
Inherited autosomal recessive condition
point mutation where valine replaces glutamic acid at position 6 on the B globulin gene
what is sickle cell like in neonates
Hbf protects from crises - as the Hb f reduces then the chronic haemolytic anaemia develops
Clinical manifestation of sickle cell
Sickle cell - reduced life expectancy by 25 years
Sickle cell crises - precipitated by infection
vaso occlusive crises - increase viscosity causes infarction and end organ damage
sequestration
aplastic (often associated with parovirus infection)
Increase risk of infection by encapulated organisms as splenic function lost
Anaemia- haemolysis
Acute chest syndrome- fat emboli form bone infarction - fever, high P RR pain anaemia pulm infiltrates
Sudden death
carriers may not be anaemic but could have severe sickling in pregnancy or puerperium
obstetric risks with sickle cell
perinatal mortality increases 4-6X Increase risk miscarriage IUGR PET Abruption FD + LSCS Maternal: 2.5% mortality
Carriers have increased risk of UTIs, renal papillary necrosis and PET
Sickle cell antenatal management
First visit
All of the above if not performed pre pregnancy .. including genetic screening
MDT approach including obstetrician and haematologist experienced in SCD
Advice about avoiding precipitators to crises (cold, hypoxia, dehydration)
High dose folic acid throughout T1
Aspirin for PET prophylaxis from 12 weeks
Penicillin prophylaxis
SCD pts are hyposplenic and at risk of infections from encapsulated organisms eg Neisseria meningitides, streptococcus pneumonia, Haemophilis influenzae
Woman should have a viability scan at 7-9 weeks
Ongoing management
Routine nuchal scan
Detailed anatomy
Monitor anaemia – Hb each visit
Urine dip for protein and BP each visit for monitoring for PET
MSU for culture monthly
LMWH if admitted and throughout pregnancy on consideration of other risk factors
Monitor for complications eg sickle cell crisis, acute chest syndrome, and treat with analgesia and fluid
Growth scans 2-4 weekly from 24 weeks with umbilical artery doppler if FGR is diagnosed
Routine Blood transfusion is not recommended
If required for management of a sickle cell complication blood should have extended phenotype testing, Rh C,D,E and Kell – blood should be CMV negative
Anaesthetic review in pregnancy
Sickle cell intrapartum management
Del 38-40 weeks Deliver in hospital LSCS for obstetric indications Recommend epidural Avoid pethidine – increases he risk of seizures Avoid sepsis and dehydration and hypothermia CEFM Cross match if atypical antibodies
how do you manage sickle cell crisis
Admission with input haematology and anaesthetics
Analgesia - IV opiates often required
Warm, hydrated, oxygenated, prophylactic
what are thalassaemias
describe the pathophysiology
thalassaemias are inherited haemoglobinopathies
There is an imbalance of the normal globin genes causing and imbalance of the globin production.
A thalassaemia causes an excess of B and gamma globin
B thalassamia has an excess of A globin chains
Excess chains destroy the bone marrow and cause haemolysis in the circulation leading to anaemia and extra medullary haematopoesis
what is the epidemiology of thalassaemias
A - southern chia, malaysia thailand (alpha thalassaemia 1 aa/– more severe + likely to result in neonatal hydrops)
mild forms in african orgin (altha thalassaemia 2 a-/a-)
B - African origin heterozygous 13% 4% asia, 2% US
Prenatal sickle cell management
Immunise hep A, B, pneumococcal, meningococcal, H influenza - rubella
Hb
Cr, LFTs TFTs,
ECHO if had recurrent acute chest syndrome presentations as risk pulmonary hypertension
partner testing
Assess Hb S and Hb F
Stop hydroxyurea
Discussion of risks
folic acid 5mg 12/52 prepreg
Educate about signs of infection and risks
What is the risks of iron overload
cirrhosis
cardiomyopathy
endocrine abnormality - hypothyroidism, diabetes, hypogonadotrophic hypogonadism
Causes of anaemia in pregnancy
- Iron deficiency anaemia
Microcytic (pregnancy increases iron requirement 2-3X) - Folate deficiency
(increased req 10-20X) megaloblastic - Haemolytic anaemias
- B12 deficiency - inflammatory bowel / pernicious anaemia (test high LHD, pancytopenia, low holotranscobalamin, low B12)
- Anaemia prepreg - short pregnancy interval, menorrhiagic, poor diet malaria
Causes of megaloblastic anaemia
B12 or folate deficiency
Azathioprine
alcohol
Indications for 5mg folic acid
Woman with spinabifida previous sibling spina bifida haemoglobinopathy Obese BMI over 30 Diabetes AED known folate deficiency known malabsorption syndrome
what is a thalassaemia major, trait and HbH disease
Major –/–
4 gene deletion -make Hb Barts and Hb portland - not compatible with life (affinity for oxygen too high and doesnt release into the tissue, precipitates and haemolysed in the spleen)
a thal trait a-/a- carriers
HbH a-/– Variable, haemolytic anaemia, some transfusion dependent, jaundice, hepatospenomegly, growth restriction
worsened by infection parovirus 19 pregnancy fever
B thalassaemia What is major minor \+ clinical consequence
in B thalassaemia the alleles have either been deleted (-) or are mutations (o)
Major - B(o or -) / B (o or -)
anaemia, splenomegly, infections, multiple bony deformity, transfusion dependent, iron overload,
minor B/ B(o or -)
mild disease / carrier
Presents in 4-6 months as Hb F has no B chains in it (A and Gamma)
what are the types of haemophilia
What factor is involved
treatment options if the woman is symptomatic
Rare X linked disorders - mainly affect men, carriers can have sx
A - Factor VIII def 1:10 000
Some respond to desmopressin, or factor VIII
B - Factor IX def 1: 50 000 - more severe
TXA or factor IX
C- factor XI def
measure levels in pregnancy and just before del
What is von willebrand disease
how common
what is the test
What to avoid
1% of the population
inherited deficiency in VWB factor. This protein stabilized factor VIII and helps with platelet aggregation on disrupted endothelium
APTT prolonged
A functional measure of vWF is the ristocetin cofactor
What is the affect of VWBD on pregnancy
No increase in APH or miscarriage
Early pregnancy bleeding (miscarriage or ectopic) can be increased
pregnancy causes an increase in FVIII and VWB - normal levels
Drop rapidly PP - can have secondary PPH
VWB management in pregnancy
Need to ascertain prepreg / early preg what type of VWB - if it responds to desmopressin
Avoid NSAIDS and Aspirin
Possible to give concentrates of factor VIII and VWB
Pre pregnancy consult for Sickle cell disease
Prepregnancy
Education for the woman on pregnancy risks – it should be discussed at each consultation from adolescence
Contraception advice so pregnancy can be planned
Genetic screening for the partner
If the partner has a trait or affected by a haemoglobinopathy then the couple should receive appropraite counselling
Discussions around preimplantation genetic diagnosis, prenatal diagnosis and TOP
High dose folic acid pre conception and throughout pregnancy
SCD are on folic acid 1mg daily usually
Stop any teratogenic treatments – may need to wean them down
Hydroxycarbamide (hydroxyurea) should be stopped 3 months pre conception
ACEi stopped (often on as renal protective)
Screen for rubella, Hep B, HIV, Varicella,
Recommend vaccinations if not up to date and immune
H Influenza type b
Conjugated meningococcal C
Pneumococcal every 5 years
Hep B if not immune
Influenzas (should get annually)
Screen for chronic disease complications
ECHO for pulmonary hypertension (associated with an increase in mortality)
BP + Urinalysis – PET + renal disease
Retinal screening for proloferative retinopathy
Iron overload from multiple transfusions – aggressive chelation is recommended
Screen for red cell antibodies
