Haem: Obstetric Haematology Flashcards
1
Q
What haematological changes are seen in pregnancy?
A
- Mild anaemia
- Red cell mass rises (120-130%)
- Plasma volume rises (150%)
- Macrocytosis
- Normal
- Folate or B12 deficiency
- Neutrophilia
- Thrombocytopenia
- Increased platelet size
2
Q
What are the increased demands required in pregnancy?
A
- Iron requirement
- 300mg for fetus
- 500mg for maternal increased red cell mass
- Recommended daily intake 30mg - ferroportin increases in pregnancy
- Increase in daily iron absorption: 1-2mg to 6mg
- Folate requirements increase
- Growth and cell division
- Approx additional 200mcg/day required
3
Q
What does iron deficiency during pregnancy increase risk of?
A
IUGR
Prematurity
Postpartum haemorrhage
4
Q
Why is folate requirement increased during pregnancy?
A
There is increased growth and cell division
5
Q
What is normal iron absorption per day?
What is iron absorption during pregnancy?
A
Normal absorption 1-2mg a day.
This increases to 6mg during pregnancy.
6
Q
Why is iron absorption increased during pregnancy?
A
Hepcidin decreases and ferroportin levels increase. This results in increased iron absorption.
7
Q
What are the WHO recommendations of iron and folate supplements in pregnancy?
A
60mg Fe
400mcg folic acid daily
8
Q
What does folate deficiency increase risk of during pregnancy?
A
Neural tube defects
9
Q
Does platelet count increase or decrease during pregnancy?
A
Platelet count decreases during pregnancy. This may be physiological. There may be a decrease by around 10%.
10
Q
What is the cut off level of platelets required for:
- Delivery / safety for epidural or spinal anaethesia
- Surgery regarding C-section and delivery
A
- 70-80 x109/L
- 50 x109/L
11
Q
Why is a higher platelet cut off required for spinal anaesthesias compared to surgery?
A
There is a small but potentially devastating consequence of spinal haematomas if platelet count it too low.
12
Q
What are causes of thrombocytopenia in pregnancy?
A
- Physiological:
- ‘gestational’ / incidental thrombocytopenia
- Pre-eclampsia
- Immune thrombocytopenia (ITP)
- Microangiopathic syndromes
- All other causes: bone marrow failure, leukaemia, hypersplenism, DIC etc.
13
Q
What are 2 examples of microangiopathic syndromes seen in pregnancy?
A
HELLP
TTP
14
Q
What is HELLP?
A
Haemolysis
Elevated Liver enzymes
Low Platelets
15
Q
What is the most commone cause of thrombocytopaenia <150x109/L in pregnancy?
A
Gestational thrombocytopenia
16
Q
What is the most common cause of thrombocytopaenia <100x109/L in pregnancy?
A
ITP and pre-eclampsia
This suggests something pathological is occurring.
17
Q
What is gestational thrombocytopenia?
A
A physiological decrease in platelet count of about 10% during pregnancy.
18
Q
What cut off platelet count is sufficient for delivery with gestational thrombocytopenia?
A
- >50x109/L sufficient for delivery
- (>70 for epidural)
19
Q
What is the underlying mechanism of gestational thrombocytopenia?
A
Mechanism poorly defined.
Possibly due to dilution and increased consumption.
Most of the fallen platelet count occurs in 3rd trimester.
20
Q
Does gestational thrombocytopenia affect the baby?
A
No
21
Q
When does platelet count increase following gestational thrombocytopenia?
A
Platelet count rises around 2-5 days after delivery
22
Q
When does platelet count fall most during pregnancy in gestational thrombocytopenia?
A
Most of the fallen platelet count occurs in 3rd trimester
23
Q
What percent of women with preeclampsia get thrombocytopenia?
A
50%
Thrombocytopenia is proportionate to preeclampsia.
24
Q
What causes thrombocytopenia in preeclampsia?
A
Increased activation and consumption of platelets
25
What is preeclampsia associated with?
It is associated with coagulation activation (incipient DIC - normal PT, APTT)
Although platelet count is low, preeclampsia is associated with a prothrombotic phenotype.
26
When does preeclampsia and thrombocytopenia usually remmit?
Usually remits following delivery
27
What percent of thrombocytopenia during pregnancy is account for by immune thrombocytopenia (ITP)?
5% of thrombocytopenia in pregnancy
- TP may precede pregnancy
- Early onset
28
What are the treatment options for ITP in pregnancy?
* IV immunoglobulin
* Steroids (not ideal as lots of side effects including diabetes)
* Anti-D where RH D+ve
29
Why is it difficult to determine ITP from physiological gestational thrombocytopenia?
It is difficult to distinguish in patients who have had normal platelet counts before pregnancy.
A low platelet count before pregnancy is a clue that it is ITP.
30
At what point during the pregnancy does platelet count fall most due to ITP?
Platelet count tends to fall dramatically early in pregnancy if present
31
Does ITP affect the baby?
Yes / Potentially
* Unpredictable (platelets \<20 in 5%) - this is the point where intracerebral bleeds are a high risk
* 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
32
What must you avoid doing with mothers who have ITP?
* Vontousse suction
* Forceps
* Scalp electrodes on the foestus' scalp
* Blood sampling the foetus
33
Until when may a baby, born from a mother with ITP's, platelet count fall until?
5 days after birth. It may be borderline normal at birth and fall rapidly.
34
What is microangiopathic haemolytic anaemia?
* Deposition of platelets in small blood vessels
* Thrombocytopenia
* Fragmentation and destruction of rbc within vasculature
* Organ damage (kidney, CNS, placenta
35
What would you expect to see on the blood film of microangiopathic syndromes?
Schistocytes
Nucleated red cells consistent with increased red cell turnover
36
What are the causes of MAHA in pregnancy?
* PET (Preeclampsia)
* HELLP (Haemolysis, Elevated Liver enzymes, Low Platelets)
* TTP (Thrombotic thrombocytopenic purpura)
* HUS (Haemolytic uraemic syndrome)
* AFLP (Acute fatty liver of pregnancy)
* SLE (Systemic lupus erythema)
* APLS (Antiphospholipid syndrome)
37
What haemolytic condition may be exacerbated by pregnancy?
TTP
38
How is MAHA in pregnancy managed?
Management varies depending on what is going on.
39
What is the treatment for TTP?
Plasma exchange is required to remove the high molecular weight multimers - e.g. Von Willebrand Factor. Also give a source of ADAMTS13. (Lack of ADAMTS13 drives TTP)
40
What is atypical HUS caused by?
Renal disorders that are related to E. coli O157
41
What two conditions causing MAHA in pregnancy do not remit following delivery of the foetus?
TTP or HUS
42
What is a leading cause of maternal mortality?
Coagulation changes in pregnancy - VTE
43
What leg does VTE usually affect?
Left leg
44
VTE during pregnancy is more common in what type of women?
Women with high BMI
45
What coagulation changes are seen in pregnancy?
* Factor VIII and vWF - increases x3-5
* Fibrinogen - increases x2
* Factor VII -increases x0.5
**(Hypercoagulability)**
* Protein S - falls to half basal level
* PAI-1 - increases x5 fold
* PAI-2 produced by the placenta
**(Hypofibrinolytic)**
46
What is the reason for coagulation changes seen in pregnancy?
Rapid control of bleeding from the placental site (700ml/min) at time of delivery. Coagulation changes control this bleeding.
47
What are the net effects of coagulation changes seen in pregnancy?
* Increased thrombin generation
* Increased fibrin cleavage
* Reduced fibrinolysis
* Interact with other maternal factors
* This leads to an increased rate of THROMBOSIS
48
When do coagulation changes in pregnancy return back to normal?
Weeks/months after delivery
49
When are deaths due to pulmonary embolism during pregnancy most likely to occur?
Around week 40-46 gestation. However, a reasonable proportion also occur in the first trimester. A third of cases are post-partum (within 6 weeks post-partum).
50
What investigations for PE may be done during pregnancy?
* Doppler and VQ scans are SAFE to perform in pregnancy
* D-dimer is often elevated in pregnancy so is NOT useful for exclusion of thrombosis
51
What are three main factors that increase risk of thrombosis in pregnancy?
* Changes in blood coagulation
* Reduced venous return
* Vessel wall changes
52
What are variable factors during pregnancy that increase risk of thrombosis?
* Hyperemesis/dehydration
* Bed rest/immobility
* Obesity
* Preeclampsia
* Operative delivery (C-sections)
* Previous thrombosis/thrombophilia
* Age
* Parity - after 4th child, risk increases massively
* Multiple pregnancy
* Other medical probelsm: HbSS, nephrotic syndrome
* IVF: ovarian hyperstimulation
53
How may thrombosis be prevented in pregnant women?
* Identify women before they get pregnant
* Start thromboprophylaxis
* LMWH injections at a preventative dose
* TED stockings
* Either throughout pregnanyc or in peri- or post-partum period
* Highest risk will get adjusted dose LMWH
* Mobilise early
* Maintain hydration
* RCOG Green-top guideline is used to determine the risk
54
What is the treatment of thromboembolic disease in pregnancy?
* LMWH as for non-pregnant
* Safe as does not cross placenta
* RCOG recommend once or twice daily injections
* After 1st trimester monitor anti-Xa
* Stop LMWH for labour or planned delivery, esp. for epidural
* Epidural: wait 24 hours after treatment dose, 12 hours after prophylactic dose
* Once the first contraction is felt, stop LMWH injections
55
What anticoagulant drugs must you avoid in pregnancy?
Warfarin and DOACs both cross the placenta and are teratogenic.
56
What complications of pregnancy are associated with thrombophilia?
It is hypothesised that an increased tendency to thrombosis is associated with imparied placental circulation.
This results in:
* Fetal growth restriction (IUGR)
* Recurrent miscarriage
* Late fetal loss
* Abruptio placentae
* Severe PET
57
What thrombophilias are associated with pregnancy complications?
Antiphospholipid syndrome:
* Recurrent miscarriage
* Persistent Lupus anticoagulant (LA)/ anticardiolipin antibodies (ACL)
58
What pregnancy complications are indicative of anti-phospholipid 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 preeterm births before the 34th week of gestation owing to placental disease
59
What treatment may be given to improve outcome in women who have had recurrent miscarriages?
Aspirin
OR
Aspirin + Heparin
60
Why may there be a slight increase in maternal mortality rates from haemorrhage in recent years?
There may be a higher risk background population. More people with repeated C-sections which affects where the placenta implants.
61
What is placenta praevia?
The placenta is attached to the opening of the uterus. May cause haemorrhage and ultimately death.
62
What is placenta accreta?
Placenta goes through the endometrial lining.
63
What are placenta increta and percreta?
Placenta increta and then percreta goes right through the serosal lining and starts adhering to other organs.
64
What do C-sections increase the risk of?
C-sections increase the likelihood of having issues with the site of placental implantation. It is key reason for hysterectomy.
65
What are the different sites of placenta implantation?
* Placent accreta (goes through the endometrial lining)
* Placenta increta (goes into the uterine wall)
* Placenta percreta (goes through the uterine wall and can stick to other ogans)
66
What is the definition of post-partum haemorrhage?
Over 500ml blood loss
67
5% of pregnancies have blood loss of over how much?
\>1 litre of blood loss at delivery
68
What percent of women require transfusion post-partum?
* 1% after vaginal delivery
* 1-7% after C-section
69
What are the main mechanisms leading to post-partum haemorrhage?
Major factors:
* Uterine atony - uterus does not contract sufficiently to stem the blood loss
* Trauma - largely from placental problems
Haematological factors minor except:
* Haemorrahge and not replacing plasma fast enough due to dilutional coagulopathy
* DIC in abruption or amniotic fluid embolism
70
What is amniotic fluid embolism?
AFE is a rare childbirth (obstetric) emergency in which amniotic fluid enters the blood stream of the mother to trigger a serious reaction.
* Very catastrophic with high mortality rate (86%)
* Presents with sudden onset shivers, vomiting, shock, DIC
* Presumed due to Tissue Factor in amniotic fluid
* Almost all \>25 years
* Usually in third trimester
* No association with parity
71
What may predispose to disseminated intravascular coagulation (DIC) in pregnancy?
* Coagulation changes in pregnancy predispose to DIC
* Decompensation precipitated by:
* Amniotic fluid embolism
* Abruption placentae
* Retained dead fetus
* Preeclampsia (severe)
* Sepsis
72
What is abruptio placentae?
Abruptio placentae is defined as the premature separation of the placenta from the uterus
73
What are the aims of haemoglobinopathy screening?
To avoid birth of children with:
* Alpha-0 thalassaemia (Hb Bart's)
* Death in utero, hydrops fetalis
* Beta-0 thalassaemia
* Transfusion dependent
* HbSS (sickle cell disease)
* Life expectancy 43 yrs
* Other compound HbS syndromes
* Symptomatic, stroke etc.
* Some compound thalassaemias
* Transfusion dependent, iron overload
74
Selected individuals for screening are based on what?
Family Origin Questionnaire
75
Why may a FBC be useful in haemoglobinopathy screening?
Look at the MCH - microcytosis indicates the possibility of thalassemia
76
What is HPLC used to identify?
HPLC can identify haemoglobin variants (EXCEPT it cannot identify alpha thalassaemia)
* Alpha thalassaemia requites molecular diagnosis.
* HPLC can quantify HbA2 (\>3.5% = beta thalassemia)
77
What areas of origin is Alpha 0 an important trait to screen for?
South East Asia
Turkey
Greece
78
What are the key features of haemoglobinopathy counselling?
* Important disorders are all recessive
* Therefore if mother is heterozygous partner should be tested
* Combinations as important as homozygous states
*
79
What prenatal tests may be done to diagnose haemoglobinopathies?
* CVS sampling (10-12 weeks)
* Amniocentesis (15-17 weeks), fetal blood sampling
* Ultrasound screening for hydrops
80
How may pregnancy affect sickle cell disease?
Vaso-occlusive crises may become more frequent.
Anaemia and existing chronic diseases are exaggerated.
81
What are the complications of sickle cell disease in pregnancy?
* Fetal growth restriction
* Miscarriage, Preterm labour, (possibly) preeclampsia
* Venous thrombosis
82
What is the management of sickle cell disease in pregnancy?
* Red cell transfusion
* Prophylactic transfusion
* reduces number of vaso-occlusive episodes
* not clear whether affects fetal or maternal outcome
* Alloimmunisation - extended phenotype: Rh D c E, Kell
83
What are the differences of IDA vs. Thalassaemia trait?
84
Name 2 other important disorders in pregnancy.
* Haemolytic disease of the newborn (HDN)
* Neonatal alloimmune thrombocytopenia (NAITP)
Materanl immune responses against fetal antigens requiring monitoring and intervention during pregnancy.
85
Which of the following statements is correct?
## Footnote
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 spontaenously following delivery
D. The platelet count may fall following delivery in babies born to mothers with ITP
D. The platelet count may fall following devliery in babies born to mothers with ITP.
86
A reduction in pregnany-associated thrombosis mortality rate can be attributed to:
## Footnote
A. Lower obesity rates
B. Improved targeted thromboprophylaxis
C. Rising maternal age
D. Increase in prevalence of gestational thrombocytopenia
B. Improved targeted thromboprophylaxis
87
Which of the following statements is correct?
## Footnote
A. Decision to use antithrombotic therapy in pregnant women with history of recurrent pregnancy loss should be based on results of thrombophilia testing.
B. Aspirin and heparin have been shown to improve live birth rate in women with recurrent pregnancy loss and antiphospholipid antibodies.
B. Aspirin and heparin have been shown to improve live birth rate in women with recurrent pregnancy loss and antiphospholipid antibodies.
88
Which of the following statements is correct?
## Footnote
A. ~1 litre 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
