Obstetric Haematology Flashcards
FBC abnormalities in pregnancy
Mild anaemia
Macrocytosis
Neutrophilia
Thrombocytopenia
Cause of macrocytosis in pregnancy
Normal (physiological)
Folate or B12 deficiency
Why does mild anaemia occur in pregnancy
Red cell mass rises (120-130%)
Plasma volume rises (150%)
What are the increased iron requirements in pregnancy
300mg for the foetus
500mg for the maternal increased red cell mass
RDA: 30mg
Increase in adily iron absorption: 1-2mg to 6mg
What requirements increase in pregnancy
Iron
Folate
Why are folate requirements increased in pregnancy
Growth and cell division
Approximately additional 200mcg/day required
What can iron deficiency cause in pregnancy
IUGR
Prematurity
Postpartum haemorrhage
What are the iron and folate supplements recommended by WHO for pregnancy
WHO recommended 60mg iron + 400mcg folic acid daily during pregnancy
What is routinely supplemented in pregnancy
Folic acid
Iron is not routinely supplemented in the UK
Why is folic acid supplements recommended in pregnancy
Advice reduces risk of neural tube defects
Supplement before conception and for >12 weeks gestation
Dose of 400ug/day
What happens to the platelet count in pregnancy
Platelet count falls in pregnancy
Non-pregnancy: 225-249
Pregnancy 175-199
Causes of thrombocytopenia in pregnancy
Physiological - gestational/incidental thrombocytopenia
Pre-eclampsia
Immune thrombocytopenia (ITP)
Microangiopathic syndromes
All other causes: BM failure, leukaemia, hypersplenism, DIC, etc…
Most common cause of thrombocytopenia with platelets <150 in pregnancy
Gestational
Most common cause of thrombocytopenia with platelets <100 in pregnancy
Gestational
Most common cause of thrombocytopenia with platelets <70 in pregnancy
ITP and pre-eclampsia
What is gestational thrombocytopenia
Physiological decrease in platelet count ~ 10%
>50x109/l sufficient for delivery (>70 for epidural)
Mechanism poorly defined: Dilution + increased consumption
Baby not affected
Platelet count rises day 2 – 5 post delivery
Why does pre-eclampsia cause thrombocytopeina in pregnancy
50% get thrombocytopenia - proportionate to severity
Probably due to increased activation and consumption
Association with coagulation activation
Usually remits following delivery
Features of immune thromboycytopenia in pregnancy
5% of thrombocytopenia in pregnancy - may precede pregnancy, early onset
Baby may be affected
Treatment options for ITP in pregnancy
IVIG
Steroids, etc…
Anti-D where RhD +ve
Features of ITP effects on baby
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 are the features of microangiopathic haemolytic anaemia (MAHA)
Deposition of platelets in small blood vessels
Thrombocytopenia
Fragmentation and destruction of rbc within vasculature
Organ damage (kidney, CNS, placenta)
What are some MAHA syndromes
Pre-eclampsia
HELLP
TTP
HUS
What are the coagulation changes in pregnancy
Factor VIII and vWF increase 3-5 fold Fibrinogen increases 2 fold Factor VII increases 0.5 fold Protein S falls to half basal PAI-1 increases 5 fold PAI-2 produced by placenta increase 5 fold
A hypercoagulale and hypofibrinolytic state
Why is haemorrhage at pregnancy a risk
Pregnancy causes a hypercoagulable and hypofibrinolytic state
Rapid control of bleeding from placenta site essential at time of delivery (700ml/min blood loss)
What are the features of the procoagulant state in pregnancy
Increased thrombin generation
Increased fibrin cleavage
Reduced fibrinolysis
Interact with other maternal factors
What can occur due to the pro-coagulation state in pregnancy
Increased rate of thrombosis: PE, DVT
When in pregnancy is the greatest risk of death from PE
1st and 2nd trimesters, but risk continues into the post-partum period (6 weeks post-delivery)
What are the risk factors for PE in pregnancy
BMI >25 Personal/family history for VTE Air travel Hyperemesis gravidarum Ovarian hyperstimulaton syndrome Unrelated surgery
What are the investigations carried out for suspected PE in pregnancy
Doppler and VQ are safe to perform in pregnancy
D-dimer often elevated in pregnancy - not useful for exclusion of thrombosis
What factors increase the risk of thrombosis in pregnancy
Changes in blood coagulation Reduced venous return - approximately 85% are left DVT Vessel wall changes Hyperemesis/dehydration Bed rest Obesity - BMI>29 x 3 risk of PE Operative delivery Previous thrombosis/thrombophilia Age Parity Multiple pregnancy Other medical problems: HbSS, nephrotic syndrome IVF: ovarian hyperstimulation
What are some symptoms of PE to be vigilant of in early pregnancy
Chest pain
Shortness of breath
Leg pain
What diagnostic tests can be done for PE in pregnancy
VQ
CXR
Venogram
CTPA
What is the treatment for suspected PE in pregnancy
Thromboprophylaxis in at risk groups
Therapy should be given pending the results of further testing
How can thromboembolic disease be prevented in pregnancy
Women with risk factors should receive prophylactic heparin + TED stockings: either throughout pregnancy, or in peri post partum period, highest risk get adjusted dose of LMWH
Mobilise early
Maintain hydration
How are high risk of PE pregnant women managed
Required antenatal prophylaxis with LMWH
Continue at least 6 weeks postnatal prophylaxis
How are intermediate risk of PE pregnant women managed
Consider antenatal prophylaxis with LMWH
Continue at least 10 days postnatal prophylaxis
How is a PE in a pregnant women with three risk factors managed
Prophylaxis with LMWH from 28 weeks
When giving treatment for PE/prophylaxis, what is the management plan
LMWH as for non-pregnant women - does not cross the placenta. Give 1 or 2/day
DO NOT GIVE WARFARIN (crosses placenta)
After 1st trimester monitor anti-Xa (4 hour post 0.5-1.0u/ml)
Stop treatment for labour of planned delivery, especially for epidural…Epidural: wait 24 hours after treatment dose, 12hours after prophylactic dose
Why is thrombophilia in pregnancy associated with pregnancy complications
An increasde tendency to thrombosis is associated with impaired placental circulation
What are the complications of thrombophilia in pregnancy
IUGR Recurrent miscarriage Late foetal loss Abruptio placentae Severe PET
What is antiphospholipid syndrome
Thrombophilia associated with pregnancy complications.
Recurrent miscarriage + persistent lupus anticoagulant (LA)/ anticardiolipin antibodies (ACL)
What increases the likelihood of antiphospholipid syndrome
Adverse pregnancy outcome: three or more consecutive miscarriages before 10 weeks of gestation
One or more morphologically normal fetal losses after the 10th week of gestation
One or more preterm births before the 34th week of gestation owing to placental disease.
Beyond antiphospholipid syndrome, what other thrombophilias may be associated with pregnancy complications
AT, PC, PS deficiency
Factor V leiden
Hyperhomocysteinemia
What are the causes of post-partum haemorrhage
Placenta praevia
Placenta accreta
What is the principle reason for hysterectomy
Post partum haemorrhage
Define post-partum haemorrhage
> 500ml blood loss
5% of pregnancies have blood loss >1L at delivery
Major risk factors for post-partum haemorrhage
Uterine atony
Trauma
Haematological factors are usually minor, except: dilutional coagulopathy after resuscitation, DIC in abruption, amniotic fluid embolism
DIC in pregnancy
Coagulation changes in pregnancy predispose to DIC
What can precipitate DIC in pregnancy
Amniotic fluid embolism Abruptio placentae Retained dead foetus Pre-eclampsia (if severe) Sepsis
Features of amniotic fluid embolism
1 in 20000-30000 births
Sudden onset shivers, vomiting, shock. DIC
86% mortality
Presumed due to Tissue Factor in amniotic fluid
Almost all >25 years old
Usually third trimester
No association with parity
Symptoms of amniotic fluid embolism
Sudden onset shivers, vomiting, shock. DIC
Aims of haemoglobinopathy screening in pregnancy
To avoid birth of children with:
Alpha-thalassaemia (death in utero, hydrops fetalis)
Beta-thalassaemia (transfusion dependent)
HbSS - life expectancy 43 years
Other compound HbS syndromes - symptomatic, stroke, etc…
Some compound thalassaemias - transfusion dependent, iron overload
NHS sickle cell and thalassaemia screening programme features
In high prevalence areas
Family origin questionnaire
FBC: MCH
HPLC
Ethnicities important in alpha-thalassaemia trait
Far east
SE Asia
Greece
Turkey
Haemoglobinopathy counselling for thalassaemias
Important disorders are all recessive
Therefore if mother is heterozygous partner should be tested.
Combinations as important as homozygous states
What are the options following screening for haemoglobinopathies
Proceed Prenatal diagnosis@ CVS sampling (10-12 weeks) Amniocentesis (15-17 weeks), fetal blood sampling Ultrasound screening for hydrops
Features of sickle cell disease in pregnancy
Hb SS (sickle cell anaemia),
HbS/clinically abnormal Hb e.g. HbC; βthal
~100 pregnancies/year in SCD females in UK
Vaso-occlusive crises become more frequent
Anaemia and existing chronic diseases exaggerated
Complications of sickle cell disease in pregnancy
Foetal growth restriction
Miscarriage, preterm labour, pre-eclampsia
Venous thrombosis
Management of sickle cell disease in pregnancy
Red cell transfusion (top up or exchange)
Prophylactic transfusion: reduced number of vaso-occlusive episodes, not clear whether affects foetal or maternal outcome
Alloimmunisation - extended phenotype RhD, E, Kell
Normal or low Hb Low MCH (proportionate to Hb) Low MCHC Raised RDW Low or normal RBC Hb electrophoresis normal
Iron deficiency
Normal (rarely low) Hb Low MCH Relatively preserved MCHC Normal RDW Increased RBC Hb electrophoresis HbA2 raised in beta-thalassaemia, normal in alpha-thalassaemia trait
Thalassaemia trait
What is neonatal alloimmune thrombocytopenia and haemolytic disease of the newborn
Maternal immune response against foetal antigens requiring monitoring and intervention during pregnancy
