Haematology in Pregnancy Flashcards
What are the FBC changes in pregnancy?
Mild anaemia
Macrocytosis
Neutrophilia
Thrombocytopenia - increase platelet size
What causes the mild anaemia in pregnancy?
Red cell mass rises (120-130%)
Plasma volume rises (150%)
Results in net dilution
How does the iron requirement change in pregnancy?
Increases
300mg for foetus
500mg for maternal increased red cell mass
Increase in daily iron absorption in gut (1-2 - 6mg)
What happens to folate requirement in pregnancy?
Increases
Growth and cell division
Approximately additional 200mcg/day
What are the complications of iron deficiency in pregnancy?
IUGR
Prematurity
Postpartum haemorrhage
What is the recommended advice for folic acid supplementation?
Supplement before conception and for >12 weeks gestation
Dose 400ug/day
What is considered anaemia at different stages of pregnancy?
1st trimester Hb<110g/l
2nd/3rd trimster Hb<105g/L
postpartum Hb<100g/l
What is the platelet change in pregnancy?
Falls, increase in size
Non pregnant: 225-249 x10^9/L
Pregnant: 175-199x10^9/L
What are some pathological causes of thrombocytopenia in pregnancy?
Pre-eclampsia
Immune thrombocytopenia (ITP)
Microangiopathic syndromes
All other causes: bone marrow failure, leukaemia, hypersplenism, DIC etc
What are the platelet requirements for delivery?
• >50x10^9/l sufficient for delivery (>70 for epidural)
When does platelet count being to rise post partum?
D2-5
What are the features of thrombocytopenia in preeclampsia?
50% pre-eclampsia get thrombocytopenia
Probably due to increased activation and consumption
Associated with coagulation activation
Usually remits following delivery
What are the treatment options for immune thrombocytopenia in pregnancy?
IV immunoglobulin
Steroids
How may the baby be affected by ITP in pregnancy?
Unpredictable (platelets <20 in 5%) Check cord blood and then daily May fall for 5 days after delivery Bleeding in 25% of severely affected (IVIG if low) Usually normal delivery
What would be avoided in women with ITP due to the risk of low platelets in the foetus?
Instrumental delivery
Invasive monitoring
What characterises the microangiopathic syndromes in pregnancy?
Microangiopathic haemolytic anaemia (MAHA)
Deposition of platelets in small blood vessels
Thrombocytopenia
Fragmentation and destruction of rbc within vasculature
Organ damage (kidney, CNA, placenta)
What changes occur to coagulation factors in pregnancy?
Factor VIII and vWF increase 3-5 fold Fibrinogen increase 2 fold Factor VII increase 0.5 fold Protein S falls to half basal PAI-1 increase 5 fold PAI-2 produced by placenta
What is the net effect of coagulation changes in pregnancy?
Procoagulant state Increased thrombin generation Increased fibrin cleavage Reduced fibrinolysis Interact with other maternal factors
What is the leading cause of maternal mortality?
VTE
What is the incidence of thrombosis in pregnancy?
1 per 1000 <35 years
2 per 1000 >35 years
What thrombosis related investigations can be used in pregnancy?
Doppler and VQ are safe to perform in pregnancy
D-dimer is often elevated in pregnancy so not useful for exclusion of thrombosis
What additional factors may increase the risk of VTE in pregnancy?
Hyperemesis/dehydration Bed rest Obesity Pre-eclampsia Operative delivery Previous thrombosis Age Parity Multiple pregnancy IVF - ovarian hyperstimulation
What is used for prevention of thromboembolic disease in pregnancy?
Women with risk factors should receive prophylactic heparin + TED stockings
Mobilise early
Maintain hydration
What is the treatment of thromboembolic disease in pregnancy?
LMWH as for non-pregnant (does not cross the placenta)
After 1st trimester monitor anti Xa
Stop for labour of planned delivery, especially for epidural
What drug to treat thromboembolic disease cannot be used in pregnancy
Warfarin - crosses placenta
What can occur giving warfarin in first trimester?
Chondrodysplasia puncta Abnormal cartilage and bone formation Early fusion of epiphyses Nasal hypoplasia Short stature Asplenia Deafness Seizures
What obstetric complications can be associated with antiphospholipid sydndrome?
Recurrent miscarriage
Three or more consecutive miscarriages before 10 weeks gestation, one or more morphologiacally normal foetal loss after 10th week of gestation, one or more preterm births before 34th week of gestation owing to placental disease
What are the most common causes of fatal bleeding in pregnancy?
Placenta praevia
Placenta accreta
What defines post partum haemorrhage?
> 500ml blood loss
What are the mechanisms of post partum haemorrhage?
Major factors: uterine atony, trauma
Haematological factors minor except: dilutional coagulopathy after resuscitation, DIC in abruption, amniotic fluid embolism etc
What factors can precipitate disseminated Intravascular Coagulation?
Amniotic fluid embolism Abruptio placentae Retained dead foetus Preeclampsia (severe) Sepsis
What are the options if there is suspected haemoglobinopathy of the foetus?
Proceed
Prenatal diagnosis: CVS sampling 10-12 weeks, amniocentesis 15-17 weeks, fetal blood sampling
Ultrasound for hydrops
What are the FBC results for iron deficiency?
Hb: normal or decreased MCH: low (in proportion to Hb) MCHC: low RDW: increased RBC: low or normla Electrophoresis: normal
What are the FBC results for thalassaemia trait?
Hb: normal MCH: lower for same Hb MCHC: relatively preserved RDW: normal RBC: increased Hb electrophoresis: HbA2 increased in beta-thal trait, normal in alpha-thal trait
