haematology and pregnancy Flashcards
describe haem changes in pregnancy
Physiological anaemia Neutrophilia Mild thrombocytopenia Increased procoagulant factors Diminished fibrinolysis
describe changes to Hb in pregnancy
Maternal blood changes start at 12wk and peak at 35wk
Plasma volume increases by 40% (100% in twin pregnancy)
~3L >5-6L
Circulating red cells increase by 25%
= physiological fall in Hb
? Reduction in plasma viscosity benefit to placental perfusion
normal Hb ranges in pregnancy
WHO definition Hb <110g/l in first trimester <105g/l in second and third trimesters <100g/l in postpartum period 115 to 165g/L
causes of anaemia in pregnancy
Dilutional
Iron deficiency
Folic acid deficiency
Less common
Autoimmune haemolytic anaemia
Aplastic anaemia
impact of iron deficiency anaemia in pregnancy
Impaired psychomotor and mental development are well described in infants with iron deficiency anaemia
Preterm delivery
Low birth weight
contributing factors for iron deficiency anaemia
Increased iron demand:
requirements rise from 1-2mg a day to 6mg a day
recommended intake of elemental iron increases from 15mg to 30mg a day
parameters for iron def anaemia diagnosis in pregnancy
ferritin <15ug/l and transferrin saturation <15%
Microcytosis and hypochromia
tx for iron def anaemia in pregnancy
Start oral iron if ferritin <30
Ferrous Sulphate 200mg =65mg elemental iron
Replacement requirements in iron deficiency
100mg-200mg elemental iron per day
Low %absorption
Instructions
on an empty stomach, 1 hour before meals,
with a source of vitamin C (ascorbic acid) such as orange juice
maximise absorption
Side effects constipation, nausea black stool
recommendation for folate pre-conception
400 μg daily
5 mg daily if: previous neural tube defect, diabetes, anticonvulsants, HbSS, thalassaemia, hereditary spherocytosis
when does neutrophilia occur in pregnancy
Neutrophil count begins to increase in the second month of pregnancy
describe the progress of thrombocytopenia in pregnancy
Normal at baseline, falls during pregnancy
At term typically 10% less than baseline
8% pregnancies develop thrombocytopenia
mechanism of thrombocytopenia in pregnancy
Dilutional effect secondary to increased plasma volume
Increased platelet destruction across the placenta
causes of thrombocytopenia in pregnancy
gestational thrombocytopenia
pre-eclampsia
HELLP
ITP
hereditary thrombocytopenia
viral infection/drugs
leukaemia/lymphoma
management of thrombocytopenia- indications for initiating treatment
First second trimester
Symptomatic bleeding
Platelet count <30
Planned procedure
From 34-36 weeks gestation
Treatment aiming to reduce risk of maternal haemorhage at time of delivery
Platelet count 50-80
precautions to consider for mothers and babies with thrombocytopenia regarding delivery
For mother
Epidural contraindicated with platelet count < 80
Caesarian Section aim for platelet count >50
For baby avoid:
Fetal Scalp electrodes
Ventouse delivery
Rotational Forceps
haemostatic changes in pregnancy
Increasing concentrations of most clotting factors
Decreasing concentrations of some anticoagulants
Diminishing fibrinolytic Activity
most common factor deficiencies seen in pregnancy
vwf VII VIII IX X XII
changes to coagulation inhibitors during pregnancy
Decreased
Protein S
Unchanged/slight increase/decrease
Protein C – unchanged or slight increase
Antithrombin – unchanged or slight decrease
what happens to tissue plasminogen activator levels in pregnancy
decreases
what happens to plasminogen activator inhibitor 1 levels
rise
guidelines for VTE prophylaxis
moderate risk: previous provoked VTE w/o thrombophilia or asymptomatic standard risk thrombophilia, other risk factors–> 6wks postnatal prophylactic LMWH
high risk: previous VTE and thrombophilia/family history VTE, asymptomatic high risk thrombophilia–> prophylactic LMWH antenatal and 6w postpartum
very high risk: previous VTE on warfarin, antithrombin deficiency–> antenatal therapeutic LMWH and 6w postpartum, specialist management
pros of LMWH in pregnancy
doesn’t cross placenta
are lmwh and warfarin safe in breast feeding
yes
antenatal care required in mothers with SCA
Early recognition of organ dysfunction
Chronic haemolysis - folate supplementation
Exchange transfusion if recurrent/ severe crises
