Haematology In Pregnancy Flashcards
What are reticulocytes?
Immature red blood cells.
They are a marker for red blood cell turnover
What is the composition of blood?
- Red blood cells (1/3)
- -> circles in microscopy
- White blood cells
- -> big purple cells
- Plasma (2/3) = water, salts, enzymes, globulins, proteins, clotting factors.
—> small circles microscopy
When centrifuging, RBCs are on the bottom, WBCs are next and plasma is on the top
What is a low RBC (Hb) count called?
Anaemia
What is a high RBC (Hb) count called?
Polycythaemia
How does plasma volume and RBC mass change in pregnancy?
Plasma volume increases and hits roughly 2600ml whereby there is a plateau for the last 8 weeks
RBC mass increases
- erythropoietin rises in first trimester - it is a hormone released from the kidneys that increases RBC production from bone marrow cells (myeloid progenitors)
Is anaemia normal in pregnancy?
Yes as physiological anaemia.
Hb normally stays above 11.5g/dL (115g/L) threshold. However, Hb levels can dip to well below this during 20-24 weeks
Below 12g/dL = iron deficiency
Below 10.5g/dL = anaemia
What happens to RBC mass post-partum?
- Declines due to bleeding (haemorrhage)
Normal non-pregnant Hb (RBC) levels are reached at 3 weeks pp
Why is Iron in pregnancy important and what are the sources of it?
Important to prevent anaemia in pregnancy and in normal person
Sources
- organic (Fe2+) - red meat
- inorganic (Fe3+) - nuts, eggs, veg
Iron is needed for Hb function as it has a binding site
- stored in liver as ferritin and released to circulation where it travels to bone marrow for Hb synthesis.
- stored in bone marrow as haemosiderin
- iron is recycled as bilirubin after RBC breakdown as
Iron storage
Liver = ferritin
- Norma is 15mcg/L
Bone marrow = haemosiderin
Iron requirements
Adult male: 1mg/day
Menstruating female: 2mg/day
Pregnant female: 4-7mg/day
- needed for placenta, foetus, and for RBC to increase
Iron deficiency
- Hb <105g/L
- MCV = mean cell volume (overall cell size)
—> MCV increases up to 105fl in pregnancy due to increased iron - Serum ferritin <15mcg/L
Treatment of iron deficiency
Iron oral supplements
- no advantage to IV iron (IV is last resort as there’s anaphylaxis risk)
Side effects of iron supplements
Nausea
Abdo pain
Toilet problems
Why are B12 and folate important in pregnancy?
They are both important for DNA synthesis
B12 - meat fish + dairy
- no increase in pregnancy (can be decreased)
- stores last for 4 years
Folic acid - NEURAL TUBE DEVELOPMENT
- normal requirement = 100ug/day
- pregnancy requirement = 300-400ug/day
- stores last 3 months
What increases risk of folate deficiency?
- Hyperemesis (extreme sickness)
- Twin pregnancy
What is the 2 extremes of platelet levels?
Too many = thrombocytosis (>500x10^9/L)
Too few = thrombocytopenia (<100x10^9/L)
What cells make RBCs, WBCs and platelets?
In bone marrow
Myeloid precursors —> white blood cells
Erythroid precursors —> red blood cells
Megakaryocytes —> platelets
Why does thrombocytopenia occur in pregnancy?
Because there is increased consumption of platelets which leads to more megakaryocytes (to replace them)
Caused by
- HELLP (haemolysis, elevated liver enzymes, low platelet number)
- Pre-eclampsia
- Gestational thrombocytopenia
What causes thrombocytopenia generally (non-pregnant)?
- autoimmunity (antibodies against platelets)
- sepsis
- haemorrhage
- cardiac bypass surgery (bypass machines consume platelets as they can’t get past filter)
- hypersplenism
Gestational thrombocytopenia
Benign and not serious
- causes of 75% of all thrombocytopenia at term
- platelets are >70x10^9/L
- count recovers within 2 months of delivery
Serious thrombocytopenia
- when you see BLOOD FRAGMENTS ON A BLOOD FILM
caused by:
- pre-eclampsia
- HELLP
- haemorrhage
- amniotic embolism
What does platelet clumping on a blood film indicate?
Thrombocytopenia
- Immune thrombocytopenia
- familial thrombocytopenia
- pseudo thrombocytopenia
- Bone marrow infiltration
- hypersplenism
What causes Venous thromboembolism? (Virchow’s triangle)
- more pro-coagulant
- less anticoagulant
- reduced fibrinolysis (breakdown of fibrin in clots)
- endothelial damage
- placental separation
- surgery
- venous stasis (slow flow)
- venous distension (bulging)
- compression of external iliac vein
What is the most common cause of venous thromboembolism?
DVT
90% are on the left side and proximal as the left common iliac vein is susceptible to compression from the overlying right common iliac artery
Pregnancy exacerbates the compression because of baby -> always lie on left hand side