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Haematology - Path > Obstetric Haematology > Flashcards

Obstetric Haematology Flashcards

1
Q

What are the changes to FBC in pregnancy?

A
  • Mild anaemia
    • Red cell mass rises (120-130%)
    • Plasma volume rises (150%) - net dilution
  • Macrocytosis
    • Normal
    • Folate or B12 deficiency
  • Neutrophilia
  • Thrombocytopenia
    • Increased platelet size
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2
Q

Describe the demands on different aspects of blood during pregnancy

A
  • Iron requirement
    • 300mg for fetus
    • 500mg for maternal increased red cell mass
    • RDA 30 mg - Increase in daily iron absorption 1-2mg to 6mg
  • Folate requirements
    • Growth and cell division
    • Approx additional 200mcg/day required
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3
Q

What can iron deficiency cause for the fetus and mother?

A
  • Intrauterine growth restriction
  • Prematurity
  • Postpartum haemorrhage
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4
Q

Describe the normal Iron cycle, and how iron is used in the body.

A
  • Out of the 10-20mg iron in the diet
  • 6mg is absorbed/day
    • Transferrin transports iron in the blood
    • 1-2mg iron/day is lost through desquamation of epithelia
    • Hepicidin (75%)–> and goes into to haemoglobin and the process of erythropoiesis
    • 10-20% goes to make up ferritin
    • 5-15% goes to form part of other processes
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5
Q
  1. What is the pregnancy iron requirement?
  2. What is the recommended daily amount of iron?
A

1.

  • 300mg: fetus
  • 500mg: maternal red cell mass expansion
  1. 30mg/day
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6
Q

What does WHO recommend for pregnant women regarding iron and folate supplements in pregnancy?

A
  • WHO recommends 60mg Fe and 400mcg folic acid daily during pregnancy
  • Cochrane review - maternal Hb higher, Fe reserves higher, fetal ferritin higher but Fe/folate supplements were shown to have no effect on maternal or fetal outcome
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7
Q

What are RCOG recommendations for folate and iron supplements in pregnancy?

A
  • Folic acid
    • Advice reduced risk of neural tube defects
    • Supplement before conception and for > 12 weeks gestation
    • Dose 400ug/day
  • Iron
    • No routine supplementation in UK
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8
Q

What happens to platelet counts in pregnancy?

A
  • Platelet count falls in pregnancy
    • Non pregnant - 225-249x109/l
    • Pregnant - 175-199x109/l
  • 13% of women have platelets less than 150x109/l
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9
Q

What are the causes of thrombocytopenia in pregnancy?

A
  • Physiological
    • Gestational/incidental thrombocytopenia - most common
  • Pre-eclampsia
  • Immune thrombocytopenia - most common in severe thrombocytopenia (<70x109)
  • Microangiopathic syndromes
  • All other causes
    • Bone marrow failure
    • Leukemia
    • Hypersplenism
    • DIC
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10
Q

Describe gestational thrombocytopenia

A
  • Physiological decrease in platelet count approx 10%
  • >50x109/l sufficient for delivery (>70 for epidural)
  • Mechanism poorly defined
    • Dilution and increased consumption
  • Baby not affected
  • Platelet count rises Day 2-5 post delivery
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11
Q

Describe the relationship between preeclampsia and thrombocytopenia

A
  • 50% of people with preeclampsia get thrombocytopenia (proportionate to severity)
  • Probably due to increased activation and consumption
  • Associated with coagulation activation
  • Usually remits following delivery
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12
Q

Describe the following about immune thrombocytopenia:

  1. In pregnancy
  2. Treatment options
  3. Effect on baby
A

1.

  • 5% of thrombocytopenia in pregnancy
    • Thrombocytopenia may precede pregnancy
    • Early onset

2.

  • Treatment options:
    • IV immunoglobulin
    • Steroids etc
    • Anti-D where Rh D positive
  1. Effect on baby
  • Unpredictable (platelets <20 in 5%)
  • Check core blood and then daily
  • May fall for 5 days after delivery
  • Bleeding in 25% of severely affected
  • Usually normal delivery
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13
Q

Describe mircoangiopathic syndromes such a MAHA

A
  • Deposition of platelets in small blood vessels
  • Thrombocytopenia
  • Fragmentation and destruction of red blood cells
  • Organ damage (kidney, CNS, Placenta)
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14
Q

What does the image show?

A

Microngiopathic haemolytic anaemia (MAHA)

Film:

  • Fragments
  • Low platelets
  • Polychromasia
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15
Q

What are the major coagulation changes in pregnancy?

A
  • Hypercoagulable
    • Factor VIII and vWF - Increase 3-5 fold
    • Fibrinogen - increases 2 fold
    • Factor VII increases 0.5 fold
  • Hypofibronlytic
    • Protein S - falls to half basal
    • PAI-1 and PA1-2 - increase 5 fold

This allows for rapid control of bleeding from placental site (700ml/min) at time of delivery

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16
Q

What is the net effect of the coagulation changes in pregnancy?

A

A procoagulant state

  • Increased thrombin generation
  • Increased fibrin cleavage
  • Reduced fibrinolysis
  • Interact with other maternal factors

Increased rate of thrombosis

17
Q

When is the risk of developing a PE highest in pregnancy?

A

Highest risk in the 40-46 weeks gestation, followed by first trimester

18
Q

What are the main risk factors for VTE identified in women who died of a PE?

A
  • BMI >25
  • Family/personal history of VTE
19
Q

What is the incidence of thrombosis in pregnancy?

A
  • 1 per 1000 <35 years
  • 2 per 1000 >35 years
  • Relative risk approx x10
  • One third are post-partum
20
Q

What tests can be used in pregnancy safely to diagnose VTE?

A
  • Doppler
  • VQ scan
  • D-dimer - but this is often raised in pregnancy and will not exclude thrombosis
21
Q

What are the factors increasing risk of thrombosis in pregnancy?

  1. All
  2. Variable
A
  1. All
  • Changes in blood coagulation
  • Reduced venous return (85% left DVT)
  • Vessel wall
  1. Variable
  • Hyperemesis/dehydration
  • Bed rest
  • Obesity (BMI>29 3x risk of PE)
  • Pre-eclampsia
  • Operative delivery
  • Previous thrombosis/thrombophilia
  • Age
  • Parity
  • Multiple pregnancies
  • Other medical problems - HbSS, nephrotic syndrome
  • IVF - ovarian hyperstimulation
22
Q

How can thromboembolic disease be prevented in pregnancy?

A
  • Women with risk factors should recieve prophylactic heparin and TED stockings
    • Either throughout pregnancy or in peri-post-partum period
    • Highest risk gets adjusted dose LMWH
  • Mobilize early
  • Maintain hydration
23
Q

What is the treatment for thromboembolic disease in pregnancy?

A
  • Management:
    • LMWH as for non-pregnant
    • Does nor cross placenta
    • RCOG recommend once or twice daily
    • Do not convert to warfarin as it can cross the placenta
    • After 1st trimester monitor anti Xa
  • Stop for labour or planned delivery esp. for epidural
24
Q

What is the issue with warfarin and pregnancy?

A

Warfarin can cross the placenta. Warfarin is teratogenic in weeks 6-12 and can delay developments

25
Q

What are the complications of pregnancy hypothesized to be due to thrombophilia?

A

The hypothesis is that an increased tendency to thrombosis is associated with impaired placentl circulation

  • Resulting in
    • IUGR
    • Recurrent miscarriage
    • Late fetal loss
    • Abruptio placentae
    • Severe PET
26
Q

What pregnancy complications occur in women with Antiphospholipid syndrome?

A
  • Recurrent miscarriage and persistent lupus anticoagulant/anticardiolipin antibodies
  • Adverse pregnancy outcome - 3 more more miscarriages consecutively before 10 weeks gestation
  • One or more morphologically normal fetal losses after 10th week of gestation
  • One or more preterm birthd before the 34th week of gestation owing to placental disease
27
Q

What can be fatal causes of bleeding in pregnancy (post-partum)?

A
  • Placenta praevia
  • Placenta accreta - principal reason for having hysterectomy

Use of major obstetric haemorrhage protocols

28
Q

Describe non-fatal bleeding in pregnancy

A
  • Post partum haemorrhage - >500ml blood loss
  • 5% of pregnancies have blood loss >1 litre at delivery
  • Requires transfusion post partum
29
Q

What are the mechanisms of post-partum haemorrhage?

A
  • Major factors are:
    • uterine atony
    • trauma
  • Haematological factors are minor except:
    • dilutional coagulopathy after resuscitation
    • DIC in abruption, aminiotic fluid embolism etc
30
Q

Describe pregnancy and disseminated intravascular coagulation (DIC)

A
  • Coagulation changes in pregnancy predispose to DIC
  • Decompensation precipitated by:
    • Amniotic fluid embolism
    • Abruptio placentae
    • Retained dead fetus
    • Severe preeclampsia
    • Sepsis
31
Q

Describe an amniotic fluid embolism

  • Epidemiology
  • Signs
  • Pathophysiology
A
  • “The most catastrophic event in modern obstetrics”
  • 1 in 20,000-30,000 births
  • Sudden onset shivers, vomiting, shock, DIC
  • 86% mortality
  • Presumed due to tissue factor in amniotic fluid entering maternal bloodtream
  • Almost all >25 years
  • Usually 3rd trimester
    • Drugs to induce labor e.g. misoprostol increase risk
32
Q
  1. Why is haemoglobinopathy screening done?
  2. What screening is available?
A

1.To avoid birth of children with:

  • alpha 0 thalassaemia (Hb Barts, gamma 4)
  • Beta 0 thalassaemia - transfusion dependent
  • HbSS - sickle cell disease (reduced life expectancy)
  • Other compound HbS syndromes - symptomatic and risk of stroke
  1. NHS sickle cell and thalamassemia screening programme 2009
  • Important to know compounds as well as homozygous states for parents
  • All disorders are recessive
33
Q

What are the options if haemoglobinopathy screening is needed?

A
  • Proceed
  • Prenatal diagnosis at:
    • CVS sampling (10-12 weeks)
    • Aminocentesis (15-17 weeks), fetal blood sampling
    • Ultrasound screening for hydrops
34
Q

Describe sickle cell disease in pregnancy

  1. Epidemiology/path
  2. Complications
  3. Management
A

1.

  • HbSS - sickle cell anaemia
  • HbS - clinically normal
  • Vaso-occlusive crises become more frequent
  • Anaemia and existing chronic diseases exaggerated
  1. Complications
  • Fetal growth restriction
  • Miscarriage, preterm labour, ?pre-eclampsia
  • Venous thrombosis
  1. Management
  • Red cell transfusion (top up or exchange)
  • Prophylactic infusion
    • reduced number of vaso-occlusiv episodes
    • Not clear whether affects fetal or maternal outcome
  • Alloimmunisation - extended phenotype
35
Q

Compare and contrast what happens to the following in Iron deficiency anaemia vs thalassaemia trait

  1. Hb
  2. MCH
  3. MCHC
  4. RDW
  5. RBC
  6. Hb electrophoresis
A
36
Q

What is haemolytic disease of the newborn?

A

Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis fetalis, is an alloimmune condition that develops in a peripartum fetus, when the IgG molecules (one of the five main types of antibodies) produced by the mother pass through the placenta.

37
Q

What is neonatal alloimmune thrombocytopenia?

A

Maternal immune responses against fetal angitens causes a reduction in platelets, and is one of the leading causes of severe thrombocytopenia seen in newborns

Haematology - Path (11 decks)

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