Inherited Bleeding Disorders

Question 1

What is an inherited bleeding disorder?

Answer 1

An acquired defect which effects coagulation of the blood

Question 2

In what ways can the coagulation cascade be effected by inherited bleeding disorders?

How can platelets be effected?

Answer 2

• a reduction in one, or more, of the coagulation factors or control proteins

1. Too little clot formed - haemophilia
2. Too much clot formed - thrombophilia

• platelets can be effected in relation to:

• number
• function

Question 3

List 4 disorders that reduce coagulation factors

Answer 3

1. Factor VIII deficiency
   - haemophilia/haemophilia A
2. Factor IX deficiency
   - Christmas disease disease/haemophilia B
3. Von Willebrand’s disease
   - reduced factor VIII level
   - reduced platelet aggregation
4. Factor XI deficiency
   - common in Askenazy Jew population

Question 4

What causes haemophilia A and B?

Who is effected?

Answer 4

1. A defective gene on the X chromosome

2. Males are affected and females are carriers

Question 5

State the level of clotting factors (VIII and IX for A and B) present in severe, moderate, mild and carrier cases of haemophilia

Answer 5

1. Severe - <2% activity (<0.02 iu/ml)
2. Moderate - 2-9% activity (0.02-0.09 iu/ml)
3. Mild - 10-40% activity (0.1-0.4 iu/ml)
4. Carriers - >50% activity (>0.5 iu/ml)

Question 6

How are severe and moderate cases of haemophilia A managed?

Answer 6

1. Require the use of recombinant factor VIII

Question 7

How are mild and carrier cases of haemophilia A managed?

Answer 7

1. Majority of patients respond to DDAVP (desmopressin)
   - this releases factor VIII that has been bound to endothelial cells, giving a temporary boost factor VIII levels and clotting ability
2. In very mild cases tranexamic acid may be used
   - inhibits fibrinolysis (keeps any clot that is formed)

Question 8

Why is DDAVP only effective with occasional use?

Answer 8

Because there is a finite amount of factor VIII bound to endothelial cell walls and this takes time to re accumulate once it is released

Question 9

How are severe, moderate, mild and carrier cases of haemophilia B managed and why?

Answer 9

1. All require the use of recombinant factor IX
   - DDAVP will not work as factor IX is not bound to the cardiovascular wall
   - tranexemic acid will help with clotting but by itself is insufficient

Question 10

What are coagulation factor inhibitors and how do they effect haemophilia treatment?

Answer 10

1.These are antibodies which develop to factor VIII and IX

2. The more frequently factors are given, the higher the level of coagulation factor inhibitors
   - therefore it is important to plan treatment in order to use as few episodes of factor concentrate as possible

Question 11

What percentage of patients develop an inhibitor when they first start treatment for haemophilia?

Answer 11

1. 35-40%

- however this usually disappears shortly after treatment

Question 12

What causes von Willebrand’s disease and who does it effect?

Answer 12

1. Autosomal dominant - not transmitted by the X chromosome
   - caused by deficiency of von Willebrand factor
   - caused by reduction in factor VIII levels

• both sexes equally affected

• defective vW factor on platelets interacts badly with factor VIII so poor clot activation by platelets

Question 13

Describe types 1, 2 and 3 of vW disease

Answer 13

1. Type 1 - dominant mild
2. Type 2 - dominant mild
3. Type 3 - recessive severe

Question 14

How is vW disease managed?

Answer 14

1. In severe and moderate cases:
   - DDAVP is enough for most
2. In mild and carrier cases:
   - may only require oral tranexamic acid

Question 15

What is the incidence of inherited blood disorders in the UK?

Answer 15

1. Haemophilia A = 1 in 10,000
2. Haemophilia B = 1 in 50,000
3. vW disease = 1 in 100-500
4. Factor XI deficiency = 1 in 50,000

Question 16

Describe factors to consider when managing dental patients with inherited blood disorders

Answer 16

1. Treatments will vary in the likelihood to cause bleeding
   - non bleeding procedures can be done in primary care
2. Degree of bleeding risk will depend on baseline factor activity
   - higher factor activity gives lower risk
3. Patient treatment plan must incorporate both patient and treatment risks to decide:
   - location of treatment (hospital or primary care)
   - medical treatment needed before or after treatment

Question 17

Where is treatment carried out for patients with haemophilia?

Answer 17

1. Severe and moderate cases:
   - majority of treatment in the dental treatment unit attached to the haemophilia centre
   - prosthodontics and other no-risk treatments can be in primary care
2. Mild and carrier cases:
   - treatment shared by GDP/PDS depending upon procedure and LA needs
   - patient reviewed at the haemophilia centre dental unit every 2 years

Question 18

What LA injections are safe/not safe for haemophilia patients?

Answer 18

1. Safe
   - buccal infiltration
   - IL injections
   - Intrapapillary injections
2. Dangerous
   - inferior alveolar nerve block
   - lingual infiltration
   - posterior superior nerve block

Question 19

What precautions must be taken for extractions and surgery on a haemophilia patient?

Answer 19

1. Appropriate cover from haemophilia unit
   - needs planned in advance
   - very difficult to get ‘on-demand’ care organised

In severe and moderate cases:
- patients should be observed overnight following surgery

In mild and carrier cases:
- patients should be observed for 2-3 hours after surgery

Question 20

What is the most important aspect of care for patients with medical issues?

Answer 20

PREVENTION:

1. Dietary advice
2. Oral hygiene
3. Fluoride supplements
4. Regular dental care
5. Fissure sealant where appropriate

Question 21

Describe thrombophilia

Answer 21

1. Increased risk of clots developing
   - clot formation ability greater than clot breakdown ability
   - excessive stable clot formed inappropriately in the circulation
2. Often an acquired condition superimposed on a genetic tendency
   - can present at any point in life
3. If clot embolises it can lead to blockage of major blood vessels in the heart and/or lungs
   - pulmonary thromboembolism
   - life threatening in many cases

Question 22

List 4 inherited syndromes which can cause thrombophilia

Answer 22

1. Protein C deficiency
2. Protein S deficiency
3. Factor V Leiden
4. Antithrombin III deficiency

Question 23

List causes of blood clots which can be acquired throughout lifetime

Answer 23

1. Oral contraceptives
2. Surgery
3. Trauma
4. Cancer
5. Pregnancy
6. Immobilisation

Antiphospholipid syndrome
- lupus anticoagulants

Question 24

List 3 platelet disorders which increase bleeding and their main i causes

Answer 24

1. Thrombocytopenia
   - reduced number of platelets
2. Qualitative disorders
   - normal platelet number but abnormal function
3. Increased platelet number
   - thrombocythemia

Question 25

What can cause the reduced number of platelets in thrombocytopenia?

Answer 25

1. May be idiopathic
2. Drug related
   - alcohol
   - penicillin based drugs
   - heparin
3. Secondary lymphoproliferative disorder - leukaemia or myelodysplasia

Question 26

What is the safe level of platelets for dental treatment to be carried out in:
Primary care setting

Hospital setting

Answer 26

1. Primary care:
   - 100x10^9/L

Hospital:
- 50x10^9

Question 27

How is thrombocythemia managed?

Answer 27

1. Patient usually on aspirin to prevent clot formation

Question 28

What is the main characteristic of thrombocythemia?

Answer 28

High numbers of (often poor) functioning platelets

Question 29

When is special care required for patients with platelet disorders?

Answer 29

1. Extractions
2. Minor oral surgery
3. Periodontal surgery
4. Biopsies

Question 30

What are common reasons for thrombophilia?

Answer 30

1. Antithrombin III deficiency

- proteins c and s deficiency