Obstetric Haematology Flashcards
What is the normal full blood count in pregnancy?
Mild anaemia: Red cell mass rises (120 -130%), plasma volume rises (150%)- net dilution
Macrocytosis: Phsyiological (+/- folate or B12 deficiency)
Neutrophilia
Thrombocytopenia: Increased turnover + platelet size
What is the blood iron requirement of pregnancy?
Fetus: 300mg
Maternal increased red cell mass: 500mg
RDA 30mg
Increase in daily iron absorption: from 1-2mg to 6mg
What is the folate requirement of pregnancy?
Increases for growth + cell division
~ additional 200mcg/day
What may iron deficiency in pregnancy cause?
IUGR
Prematurity
Postpartum haemorrhage
What is the importance of folic acid in pregnancy? What is the normal supplementation of folic acid in pregnancy?
Reduces risk of neural tube defects
Supplement before conception + for ≥ 12w gestation
Dose 400μg/day
What is the definition of anaemia in each trimester and postpartum?
1: Hb < 110 g/l
2 + 3: Hb <105 g/l
Postpartum: <100g/l
What is defined as major haemorrhage during labour?
Blood loss 1L
What happens to platelets during pregnancy? What must be considered?
Platelet count falls due to increased turnover
Automated counter may not recognise giant platelets
Be aware of clumping- use film
What are 5 causes of thrombocytopaenia in pregnancy?
Physiological: ‘Gestational’/ incidental thrombocytopenia
Pre-eclampsia
Immune thrombocytopenia (ITP)
Microangiopathic syndromes
Normal causes: BM failure, leukaemia, hypersplenism, DIC
What is the likely cause of thrombocytopenia at each of the following platelet counts:
<150
<100
<70
<150: majority gestational, little preeclampsia, few ITP
<100: ½ gestational, ¼ ITP, ¼ preeclampsia
<70: ¼ gestational, majority ITP + Pre-eclampsia
What is gestational thrombocytopaenia?
Physiological decrease in platelet count ~ 10%
>50x10^9/l sufficient for delivery (>70 for epidural)
MOA: Dilution + increased consumption
Baby not affected
Platelet count rises 2–5d post delivery
What is the association between pre-eclampsia and thrombocytopenia?
50% with pre-eclampsia get thrombocytopenia
Proportionate to severity
MOA: Increased activation + consumption
A/w coagulation activation: incipient DIC
Usually remits following delivery
Why is a greater platelet count required for epidural?
Small risk of spinal haematoma when sticking needles around spine
What is the epidemiology of ITP?
Accounts for. 5% of thrombocytopenia in pregnancy
TP may precede pregnancy
Early onset
What are treatment options for bleeding or delivery in ITP?
IV immunoglobulin
Steroids etc.
Vontouse delivery/ certain forceps avoided
How are babies affected with maternal ITP?
Unpredictable effects (causes platelets <20 in 5%)
Check cord blood + then daily
May fall for 5d after delivery
Bleeding in 25% of severely affected (IVIG if low)
Usually normal delivery
What occurs in MAHA in pregnancy?
Deposition of platelets in small blood vessels- thrombocytopenia
Fragmentation + destruction of RBCs
Stress on BM to produce more RBCs- nucleated RBC on film
Can lead to organ damage
In which MAHA syndromes does delivery not alter the course?
TTP
HUS
Coagulation changes in pregnancy…
A. Increase the likelihood of bleeding
B. Result in hyperfibrinolytic state
C. Are mediated by BHCG hormone
D. Result in a leading cause of maternal mortality
D. Result in a leading cause of maternal mortality
Venous Thromboembolism during pregnancy…
A. Has a higher incidence period during the postnatal period
B. Is more common in women with high body mass index
C. Is more likely to occur following vaginal delivery than elective C section
D. Usually affects the right leg
B. Is more common in women with high body mass index
85% of clots in pregnant women in left leg
What is the direct leading cause of maternal death in the UK?
PE
Which coagulation factors increase in pregnancy creating a hypercoaguable state?
Factor VIII + vWF x 3-5
Fibrinogen x 2
Factor VII x 0.5
Factor X
Which coagulation factors change in pregnancy creating a hypofibrinolytic state?
Protein S falls to ½
PAI-1 increases 5-fold
PA-2 produced by placenta
What do the coagulation changes in pregnancy result in?
Hypercoaguable hypofibrinolytic state
Rapid control of bleeding from placental site (700ml/min) at time of delivery
Why can D-dimers not be used in pregnancy?
D dimers rise in pregnancy due to inflammation
Pregnancy: hypercoaguable + HYPOfibrinolytic
D dimers in non-pregnant are used as markers of fibrinolysis
Summarise the net effect of coagulation changes in pregnancy
Procoagulant state:
Increased thrombin generation
Increased fibrin cleavage
Reduced fibrinolysis
Increased rate of thrombosis
Which tests are used to identify VTE in pregnancy?
VQ perfusion or Doppler
(NOT D-Dimer)
What are factors which increase risk of VTE in all pregnant women? (Virchows triad)
Blood changes: hypercoagulable
Developing gravid uterus presses down, reduced venous return- venous stasis
Changes in vessel wall related to hormones
Why does 85% od DVT occur in the left leg in pregnancy compared to 55% in the left leg in the non pregnant state?
Anatomy: compression of left common iliac vein by right common iliac artery is accentuated by enlarging uterus
More pressure on left side
When is risk of VTE highest in pregnancy?
Postpartum
Up till 6w after birth
What has a ‘dose dependent’ effect on risk of PE death in pregnancy?
BMI
What 11 variable factors which increase risk of VTE in pregnant women?
Hyperemesis/ dehydration
Bed rest
Obesity: BMI>29 3x risk of PE
Pre-eclampsia
Operative delivery
Previous thrombosis/ thrombophilia
Age
Parity (>4)
Multiple pregnancy
Other medical problems: HbSS, nephrotic syndrome
IVF: ovarian hyperstimulation
Which women are identified to seek advice before becoming pregnant to reduce risk of VTE?
Overweight
FH VTE
PMH VTE
Give 4 symptoms of VTE in early pregnancy
Chest pain
SOB
Tachycardia
Leg pain
What preventative measures are recommended for women with risk factors for VTE during pregnancy?
Prophylactic LMWH: either throughout or in peri-post-partum
TED stockings
Early mobilisation
Maintain hydration
What is the treatment for VTE in pregnancy?
LMWH as for non-pregnant; does not cross placenta.
RCOG recommend OD/ BD
Do not convert to warfarin (crosses placenta)
After 1st trimester monitor anti-Xa: 4 hour post 0.5-1.0u/ml
How long before an epidural should LMWH be stopped?
Wait 24h after tx dose
12h after prophylactic dose
Give 7 signs of chondrodysplasia punctata
Abnormal cartilage + bone formation
Early fusion of epiphyses
Nasal hypoplasia
Short stature
Asplenia
Deafness
Seizures
Why should warfarin not be given?
Warfarin is teratogenic in the 1st trimester
Can cause Chondrodysplasia Punctata
What is antiphospholipid syndrome?
Recurrent miscarriage + persistent Lupus anticoagulant (LA) +/- antiphospholipid antibodies
What are the three potential presentations of antiphospholipid syndrome?
Adverse pregnancy outcome: >,3 consecutive miscarriages before 10w gestation.
>,1 morphologically normal fetal losses after 10w gestation.
>,1 preterm births before 34w gestation owing to placental disease.
What is the potential treatment of antiphospholipid syndrome?
Aspirin + heparin
(Better than aspirin alone)
What are the 4 Ts of postpartum haemorrhage?
Tone: Uterine atony
Trauma: Laceration/ Uterine rupture
Tissue: Retained placenta/ site of placenta
Thrombin: Coagulopathy
What amount of blood loss defines post party haemorrhage?
>500ml
All haematological factors are minor variables for post-partum haemorrhage except:
Dilutional coagulopathy after resuscitation
DIC caused by infection, placental abruption, amniotic fluid embolism etc.
What is the relationship between Disseminated Intravascular Coagulation (DIC) and pregnancy?
Coagulation changes in pregnancy predispose to DIC.
What is decomposition for DIC in pregnancy precipitated by?
Amniotic fluid embolism
Abruptio placentae
Retained dead fetus
Preeclampsia (severe)
Sepsis
List 3 signs/ symptoms of amniotic fluid embolism
Sudden onset shivers
Vomiting
Shock
Give 4 facts about amniotic fluid embolism
86% mortality
Presumed due to Tissue Factor in amniotic fluid entering maternal bloodstream
Majority >25y
Usually 3rd trimester: drugs used to induce labour e.g. Misoprolol increase risk
The aims of haemoglobinopathy screening are to avoid birth of children with…
Alpha thalassaemia: death in uteru, hydros fetalis
Beta thalassaemia: Transfusion dependent
HbSS (sickle cell disease): Life expectancy 43y
Compound HbS syndromes: symptomatic, stroke
Compound thalassaemias: transfusion dependent, iron overload
What elements are used for haemoglobinopathy detection?
Universal screening in areas with high background prevalence
Family origin questionnaire in less prevalent areas
FBC: Red cell indicies
HPLC
Molecular analysis
Aim to complete by 12/40w
What should be considered in haemaglobinopathy counselling?
Important disorders are all recessive
Therefore if mother is heterozygous, partner should be tested
Describe the following parameters in iron deficiency:
Hb
MCH
MCHC
RDW
RBC
Hb: Normal/ Low
MCH: Low (in proportion to Hb)
MCHC: Low
RDW: Increased
RBC: Low/ normal
Hb electrophoresis: Normal
Describe the following parameters in thealassaemia trait:
Hb
MCH
MCHC
RDW
RBC
Hb electrophoresis
Hb: Normal (rarely low)
MCH: Lower for same Hb
MCHC: Relatively preserved
RDW: Normal
RBC: Increased
Hb electrophoresis: HbA2 in b thal trait, Normal in alpha thal trait
What key difference in parameters distinguish thalassaemia trait from iron deficiency?
RBC cannot be increased in iron deficiency but is
ALWAYS increased in Thal trait
Which of the following statements is correct?
A. In gestational thrombocytopenia the baby’s platelet count is usually affected
B. Thrombocytopenia is rarely found in association with pre-eclampsia
C. Thrombotic Thrombocytopenic purpura remits spontaneously following delivery
D. The platelet count may fall following delivery in baby’s born to mothers with ITP
D. The platelet count may fall following delivery in baby’s born to mothers with ITP
A reduction in pregnancy-associated thrombosis mortality rate can be attributed to:
A. Lower obesity rates
B. Improved targeted thromboprophylaxis
C. Rising maternal age
D. Increase in prevalence of gestational thrombocytopenia
B. Improved targeted thromboprophylaxis
Which of the following statements is correct?
A. ~1L blood loss can be considered normal following vaginal delivery
B. Uterine atony is a common cause of post partum haemorrhage
C. Post partum haemorrhage is often caused by the changes in coagulation factors in pregnancy
B. Uterine atony is a common cause of post partum haemorrhage
