Haematological changes in Pregnancy Flashcards
How much does Hb decline by?
110 -> 100 g/l
- Techincally increases in pregnancy but bigger increase in plasma volue
What WBCs increase the most?
Neutrophils
What is “gestational thrombocytopenis”?
Fall in plateltes in pregnancy to lower limit of 80-90x10^11/L
What is the increase in mean cell volume (MCV)?
4 L (eg 84 to 88)
What fibrinogen factors are increased to create a hypercoagulable state?
Factors:
- VIII
- IX
- X
Amounts of what substance should be checked to see if a woman has iron deficiency anaemia?
Ferritin (MCV may be normal)
What are the common side-effects of iron supplementation which is often given in pregnancy?
- Constipation
- Abdo pain
- Nausea
What is a type of IV iron medication?
Ferinject (not as common as oral)
What is given to reduce neural tube defects (formed in 2-4 wks post conception)?
400mcg/day
What can immune thrombocytopenic purpura (ITP) be triggered by?
Infection, drug or pregnancy
What causes immune thrombocytopenia purpura?
Auto antibodies to platelets (marrow normal)
How is immune thrombocytopenia purpura treated?
- Watch and wait
- Steroids
- Immunoglobulins
- Splenectomy
- Drugs to mimic thrombopoetin
- Fetal scalp sample can be taken to check if IgG antibodies have crossed from placenta to cause ITP in fetus
What is Thrombotic Thrombocytopenc Purpura (TTP)?
- Rare but life-threatening “thrombotic microangiopathy”
- Enzyme ADAMS13 prevents large Von Willebrands polymers - this becomes deficient and platelets aggregate
- Present as fever, neurological and renal disease, low platelets and fragmented red cells. Coagulation screen usually normal
What enzyme causes TTP?
ADAMS13
What is Thrombotic thrombocytopenic purpura associated with?
Auto-immune disease, HIV, pregnancy
How is thrombotic thrombocytopenic purpura treated?
Plamsa exchange (to replace ADAMS13)
What is the UK maternal death rate in pregnancy?
9 per 100,000
What is the leading cause in the UK of maternal death in pregnancy
Pulmonary embolism `
What is the high-risk area for thromboembolic disease?
- Pregnancy plus 6 weeks post-partum (hypercoagulable state)
What factors increase the risk of thromboembolic disease?
- Age
- Previous clot
- Smoking
- Twins
- Obesity
- Thrombophillia eg anti-thrombin deficiency
What is thought to cause leg swelling in pregnancy?
- Pelvic veins being compressed in late pregnancy (L>R)
- Can also lead to DVT
How can thromboembolisms be diagnosed?
- Doppler exam of leg
- CXR - if abnormal CT pulmonary angiogram (higher radiation dose) more reliable than ventilation/perfusion scan
- NOT D dimers
How is thromboembolic disease treated in pregnancy?
- Low molecular weight heparin
- Increase rate of clearence and volume of distribution requires twice daily dose
- Monitoring of anti Xa levels (3-4 hours post dose) required to show effective dosing
- Will need prophyactic anticoagulation in future pregnancies
What can PET lead to in a minority of cases?
HELLP
- Haemolysis (anaemia, red cell fragments, raised LDH)
- Elevated liver enzymes
- low platelet count
What are the risk factors for a major haemorrhage ante or post- partum?
- Placenta praevia (over cervix)
- Placental abruption
- Retained products of conception
- Poor uterine contraction after delivery
How are major haemorrhages treated?
Treat the cause and replace red cell/platelets/coagulation factors
What are the Wilson and Junger screening criteria?
- Recognisable latent or early symptomatic stage
- A simple test with high sensitivity and specificity
- Test should be acceptable to the population
- Early effective treatment needs to be clear of benefit
- Agreement as to who should be treated
- Condition is an important health problem
- Diagnosis an treatment should be cost-effective
- Case finding should be a continous process
- Natural history should be understood
- It should be cost effective in relation to overall health-care expenditure
Why is Scotland considered “low prevalence” for haemoglobinopathies and thalassemia?
Low asian and afro-caribbean populations
What makes up heamoglobin (HbA)?
- 2 alpha-like chains
- 2 beta-like chains
What other haemoglobins are present in the adult blood other than HB A and what are they made up of?
- Hb A2 = 2 alpha, 2 delta (2.5%)
- Hb F (foetal) = 2 alpha, 2 gamma (0.5%)
What chromosome codes for the alpha-like chains?
16
What chromosome codes for the beta-like chains?
11
What will the MCV be like in individuals with a haemoglobinopathy or thalasemia?
Microcytic MCV < 80 and mean cell Hb < 27
How can haemoglobinopathy or thalasemia be diagnosed?
- Ethnic origin
- Microcytic
- Blood film - target cells in thal heterozygous , sickle slide test
- Cellulose acetate or agarose gel Hb electrophoresis
- High performance Liquid Chromatography (HPLC)
- Gene copy number
- Gene sequencing
What will abnormal haemoglobins show on?
Electrophoresis/HLPC
What will HbA2 be in beta thal heterozygous?
> 3.5% (also low MCV and MCH)
What will alpha thalasemia with 1 deletion show?
- No change, 2 deletions, low MCV
- Gene copy number or sequencing may be needed
How is pre-natal screening done for haemoglobinopathy or thalasemias in low prevelance areas?
- FBC (approx 12 wks) - is MCH <27pg?
- Family origin q’s for both parteners
- If either positive then HPLC ook for thal/haemoglobinopathy
- May need confirmaatory tests
- May need to check partner’s FBC etc (beware non-paternity)
What is consodered igf foetus is at risk of serious Hb disorder?
- 11-14 wks chorionic villous sampling for foetal DNA or 15 wks + amniocentresis
- Possible termination?
- Newborn screening includs sickle cell disease on heel prick
What are the embryonic globins?
- Zeta which is replaced by alpha
- Episilon replaced by gamma then delta then beta
